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0d5d1aadc8
This patch adds NULL pointer checking in the early_alloc() function. Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1690 lines
47 KiB
C
1690 lines
47 KiB
C
/*
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* mm/kmemleak.c
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*
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* Copyright (C) 2008 ARM Limited
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* Written by Catalin Marinas <catalin.marinas@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*
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* For more information on the algorithm and kmemleak usage, please see
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* Documentation/kmemleak.txt.
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*
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* Notes on locking
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* ----------------
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*
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* The following locks and mutexes are used by kmemleak:
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*
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* - kmemleak_lock (rwlock): protects the object_list modifications and
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* accesses to the object_tree_root. The object_list is the main list
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* holding the metadata (struct kmemleak_object) for the allocated memory
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* blocks. The object_tree_root is a priority search tree used to look-up
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* metadata based on a pointer to the corresponding memory block. The
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* kmemleak_object structures are added to the object_list and
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* object_tree_root in the create_object() function called from the
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* kmemleak_alloc() callback and removed in delete_object() called from the
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* kmemleak_free() callback
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* - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
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* the metadata (e.g. count) are protected by this lock. Note that some
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* members of this structure may be protected by other means (atomic or
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* kmemleak_lock). This lock is also held when scanning the corresponding
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* memory block to avoid the kernel freeing it via the kmemleak_free()
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* callback. This is less heavyweight than holding a global lock like
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* kmemleak_lock during scanning
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* - scan_mutex (mutex): ensures that only one thread may scan the memory for
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* unreferenced objects at a time. The gray_list contains the objects which
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* are already referenced or marked as false positives and need to be
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* scanned. This list is only modified during a scanning episode when the
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* scan_mutex is held. At the end of a scan, the gray_list is always empty.
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* Note that the kmemleak_object.use_count is incremented when an object is
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* added to the gray_list and therefore cannot be freed. This mutex also
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* prevents multiple users of the "kmemleak" debugfs file together with
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* modifications to the memory scanning parameters including the scan_thread
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* pointer
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*
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* The kmemleak_object structures have a use_count incremented or decremented
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* using the get_object()/put_object() functions. When the use_count becomes
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* 0, this count can no longer be incremented and put_object() schedules the
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* kmemleak_object freeing via an RCU callback. All calls to the get_object()
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* function must be protected by rcu_read_lock() to avoid accessing a freed
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* structure.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/sched.h>
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#include <linux/jiffies.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/prio_tree.h>
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#include <linux/gfp.h>
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#include <linux/fs.h>
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#include <linux/debugfs.h>
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#include <linux/seq_file.h>
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#include <linux/cpumask.h>
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#include <linux/spinlock.h>
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#include <linux/mutex.h>
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#include <linux/rcupdate.h>
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#include <linux/stacktrace.h>
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#include <linux/cache.h>
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#include <linux/percpu.h>
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#include <linux/hardirq.h>
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#include <linux/mmzone.h>
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#include <linux/slab.h>
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#include <linux/thread_info.h>
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#include <linux/err.h>
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#include <linux/uaccess.h>
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#include <linux/string.h>
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#include <linux/nodemask.h>
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#include <linux/mm.h>
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#include <linux/workqueue.h>
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#include <asm/sections.h>
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#include <asm/processor.h>
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#include <asm/atomic.h>
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#include <linux/kmemcheck.h>
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#include <linux/kmemleak.h>
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/*
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* Kmemleak configuration and common defines.
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*/
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#define MAX_TRACE 16 /* stack trace length */
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#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
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#define SECS_FIRST_SCAN 60 /* delay before the first scan */
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#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
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#define GRAY_LIST_PASSES 25 /* maximum number of gray list scans */
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#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
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#define BYTES_PER_POINTER sizeof(void *)
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/* GFP bitmask for kmemleak internal allocations */
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#define GFP_KMEMLEAK_MASK (GFP_KERNEL | GFP_ATOMIC)
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/* scanning area inside a memory block */
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struct kmemleak_scan_area {
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struct hlist_node node;
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unsigned long offset;
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size_t length;
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};
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#define KMEMLEAK_GREY 0
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#define KMEMLEAK_BLACK -1
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/*
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* Structure holding the metadata for each allocated memory block.
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* Modifications to such objects should be made while holding the
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* object->lock. Insertions or deletions from object_list, gray_list or
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* tree_node are already protected by the corresponding locks or mutex (see
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* the notes on locking above). These objects are reference-counted
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* (use_count) and freed using the RCU mechanism.
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*/
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struct kmemleak_object {
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spinlock_t lock;
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unsigned long flags; /* object status flags */
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struct list_head object_list;
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struct list_head gray_list;
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struct prio_tree_node tree_node;
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struct rcu_head rcu; /* object_list lockless traversal */
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/* object usage count; object freed when use_count == 0 */
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atomic_t use_count;
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unsigned long pointer;
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size_t size;
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/* minimum number of a pointers found before it is considered leak */
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int min_count;
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/* the total number of pointers found pointing to this object */
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int count;
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/* memory ranges to be scanned inside an object (empty for all) */
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struct hlist_head area_list;
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unsigned long trace[MAX_TRACE];
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unsigned int trace_len;
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unsigned long jiffies; /* creation timestamp */
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pid_t pid; /* pid of the current task */
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char comm[TASK_COMM_LEN]; /* executable name */
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};
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/* flag representing the memory block allocation status */
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#define OBJECT_ALLOCATED (1 << 0)
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/* flag set after the first reporting of an unreference object */
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#define OBJECT_REPORTED (1 << 1)
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/* flag set to not scan the object */
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#define OBJECT_NO_SCAN (1 << 2)
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/* flag set on newly allocated objects */
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#define OBJECT_NEW (1 << 3)
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/* number of bytes to print per line; must be 16 or 32 */
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#define HEX_ROW_SIZE 16
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/* number of bytes to print at a time (1, 2, 4, 8) */
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#define HEX_GROUP_SIZE 1
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/* include ASCII after the hex output */
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#define HEX_ASCII 1
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/* max number of lines to be printed */
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#define HEX_MAX_LINES 2
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/* the list of all allocated objects */
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static LIST_HEAD(object_list);
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/* the list of gray-colored objects (see color_gray comment below) */
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static LIST_HEAD(gray_list);
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/* prio search tree for object boundaries */
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static struct prio_tree_root object_tree_root;
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/* rw_lock protecting the access to object_list and prio_tree_root */
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static DEFINE_RWLOCK(kmemleak_lock);
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/* allocation caches for kmemleak internal data */
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static struct kmem_cache *object_cache;
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static struct kmem_cache *scan_area_cache;
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/* set if tracing memory operations is enabled */
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static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
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/* set in the late_initcall if there were no errors */
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static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
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/* enables or disables early logging of the memory operations */
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static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
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/* set if a fata kmemleak error has occurred */
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static atomic_t kmemleak_error = ATOMIC_INIT(0);
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/* minimum and maximum address that may be valid pointers */
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static unsigned long min_addr = ULONG_MAX;
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static unsigned long max_addr;
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static struct task_struct *scan_thread;
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/* used to avoid reporting of recently allocated objects */
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static unsigned long jiffies_min_age;
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static unsigned long jiffies_last_scan;
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/* delay between automatic memory scannings */
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static signed long jiffies_scan_wait;
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/* enables or disables the task stacks scanning */
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static int kmemleak_stack_scan = 1;
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/* protects the memory scanning, parameters and debug/kmemleak file access */
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static DEFINE_MUTEX(scan_mutex);
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/*
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* Early object allocation/freeing logging. Kmemleak is initialized after the
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* kernel allocator. However, both the kernel allocator and kmemleak may
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* allocate memory blocks which need to be tracked. Kmemleak defines an
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* arbitrary buffer to hold the allocation/freeing information before it is
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* fully initialized.
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*/
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/* kmemleak operation type for early logging */
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enum {
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KMEMLEAK_ALLOC,
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KMEMLEAK_FREE,
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KMEMLEAK_FREE_PART,
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KMEMLEAK_NOT_LEAK,
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KMEMLEAK_IGNORE,
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KMEMLEAK_SCAN_AREA,
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KMEMLEAK_NO_SCAN
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};
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/*
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* Structure holding the information passed to kmemleak callbacks during the
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* early logging.
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*/
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struct early_log {
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int op_type; /* kmemleak operation type */
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const void *ptr; /* allocated/freed memory block */
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size_t size; /* memory block size */
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int min_count; /* minimum reference count */
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unsigned long offset; /* scan area offset */
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size_t length; /* scan area length */
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unsigned long trace[MAX_TRACE]; /* stack trace */
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unsigned int trace_len; /* stack trace length */
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};
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/* early logging buffer and current position */
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static struct early_log
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early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
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static int crt_early_log __initdata;
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static void kmemleak_disable(void);
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/*
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* Print a warning and dump the stack trace.
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*/
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#define kmemleak_warn(x...) do { \
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pr_warning(x); \
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dump_stack(); \
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} while (0)
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/*
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* Macro invoked when a serious kmemleak condition occured and cannot be
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* recovered from. Kmemleak will be disabled and further allocation/freeing
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* tracing no longer available.
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*/
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#define kmemleak_stop(x...) do { \
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kmemleak_warn(x); \
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kmemleak_disable(); \
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} while (0)
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/*
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* Printing of the objects hex dump to the seq file. The number of lines to be
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* printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
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* actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
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* with the object->lock held.
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*/
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static void hex_dump_object(struct seq_file *seq,
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struct kmemleak_object *object)
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{
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const u8 *ptr = (const u8 *)object->pointer;
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int i, len, remaining;
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unsigned char linebuf[HEX_ROW_SIZE * 5];
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/* limit the number of lines to HEX_MAX_LINES */
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remaining = len =
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min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
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seq_printf(seq, " hex dump (first %d bytes):\n", len);
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for (i = 0; i < len; i += HEX_ROW_SIZE) {
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int linelen = min(remaining, HEX_ROW_SIZE);
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remaining -= HEX_ROW_SIZE;
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hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
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HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
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HEX_ASCII);
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seq_printf(seq, " %s\n", linebuf);
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}
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}
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/*
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* Object colors, encoded with count and min_count:
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* - white - orphan object, not enough references to it (count < min_count)
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* - gray - not orphan, not marked as false positive (min_count == 0) or
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* sufficient references to it (count >= min_count)
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* - black - ignore, it doesn't contain references (e.g. text section)
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* (min_count == -1). No function defined for this color.
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* Newly created objects don't have any color assigned (object->count == -1)
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* before the next memory scan when they become white.
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*/
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static bool color_white(const struct kmemleak_object *object)
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{
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return object->count != KMEMLEAK_BLACK &&
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object->count < object->min_count;
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}
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static bool color_gray(const struct kmemleak_object *object)
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{
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return object->min_count != KMEMLEAK_BLACK &&
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object->count >= object->min_count;
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}
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static bool color_black(const struct kmemleak_object *object)
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{
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return object->min_count == KMEMLEAK_BLACK;
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}
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/*
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* Objects are considered unreferenced only if their color is white, they have
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* not be deleted and have a minimum age to avoid false positives caused by
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* pointers temporarily stored in CPU registers.
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*/
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static bool unreferenced_object(struct kmemleak_object *object)
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{
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return (object->flags & OBJECT_ALLOCATED) && color_white(object) &&
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time_before_eq(object->jiffies + jiffies_min_age,
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jiffies_last_scan);
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}
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/*
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* Printing of the unreferenced objects information to the seq file. The
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* print_unreferenced function must be called with the object->lock held.
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*/
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static void print_unreferenced(struct seq_file *seq,
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struct kmemleak_object *object)
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{
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int i;
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seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
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object->pointer, object->size);
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seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n",
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object->comm, object->pid, object->jiffies);
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hex_dump_object(seq, object);
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seq_printf(seq, " backtrace:\n");
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for (i = 0; i < object->trace_len; i++) {
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void *ptr = (void *)object->trace[i];
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seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
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}
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}
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/*
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* Print the kmemleak_object information. This function is used mainly for
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* debugging special cases when kmemleak operations. It must be called with
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* the object->lock held.
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*/
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static void dump_object_info(struct kmemleak_object *object)
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{
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struct stack_trace trace;
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trace.nr_entries = object->trace_len;
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trace.entries = object->trace;
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pr_notice("Object 0x%08lx (size %zu):\n",
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object->tree_node.start, object->size);
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pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
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object->comm, object->pid, object->jiffies);
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pr_notice(" min_count = %d\n", object->min_count);
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pr_notice(" count = %d\n", object->count);
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pr_notice(" flags = 0x%lx\n", object->flags);
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pr_notice(" backtrace:\n");
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print_stack_trace(&trace, 4);
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}
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/*
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* Look-up a memory block metadata (kmemleak_object) in the priority search
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* tree based on a pointer value. If alias is 0, only values pointing to the
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* beginning of the memory block are allowed. The kmemleak_lock must be held
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* when calling this function.
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*/
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static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
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{
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struct prio_tree_node *node;
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struct prio_tree_iter iter;
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struct kmemleak_object *object;
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prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
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node = prio_tree_next(&iter);
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if (node) {
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object = prio_tree_entry(node, struct kmemleak_object,
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tree_node);
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if (!alias && object->pointer != ptr) {
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kmemleak_warn("Found object by alias");
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object = NULL;
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}
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} else
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object = NULL;
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return object;
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}
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/*
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* Increment the object use_count. Return 1 if successful or 0 otherwise. Note
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* that once an object's use_count reached 0, the RCU freeing was already
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* registered and the object should no longer be used. This function must be
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* called under the protection of rcu_read_lock().
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*/
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static int get_object(struct kmemleak_object *object)
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{
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return atomic_inc_not_zero(&object->use_count);
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}
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/*
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* RCU callback to free a kmemleak_object.
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*/
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static void free_object_rcu(struct rcu_head *rcu)
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{
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struct hlist_node *elem, *tmp;
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struct kmemleak_scan_area *area;
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struct kmemleak_object *object =
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container_of(rcu, struct kmemleak_object, rcu);
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/*
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* Once use_count is 0 (guaranteed by put_object), there is no other
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* code accessing this object, hence no need for locking.
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*/
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hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
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hlist_del(elem);
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kmem_cache_free(scan_area_cache, area);
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}
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kmem_cache_free(object_cache, object);
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}
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/*
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* Decrement the object use_count. Once the count is 0, free the object using
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* an RCU callback. Since put_object() may be called via the kmemleak_free() ->
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* delete_object() path, the delayed RCU freeing ensures that there is no
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* recursive call to the kernel allocator. Lock-less RCU object_list traversal
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* is also possible.
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*/
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static void put_object(struct kmemleak_object *object)
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{
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if (!atomic_dec_and_test(&object->use_count))
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return;
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/* should only get here after delete_object was called */
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WARN_ON(object->flags & OBJECT_ALLOCATED);
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|
|
|
call_rcu(&object->rcu, free_object_rcu);
|
|
}
|
|
|
|
/*
|
|
* Look up an object in the prio search tree and increase its use_count.
|
|
*/
|
|
static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
|
|
{
|
|
unsigned long flags;
|
|
struct kmemleak_object *object = NULL;
|
|
|
|
rcu_read_lock();
|
|
read_lock_irqsave(&kmemleak_lock, flags);
|
|
if (ptr >= min_addr && ptr < max_addr)
|
|
object = lookup_object(ptr, alias);
|
|
read_unlock_irqrestore(&kmemleak_lock, flags);
|
|
|
|
/* check whether the object is still available */
|
|
if (object && !get_object(object))
|
|
object = NULL;
|
|
rcu_read_unlock();
|
|
|
|
return object;
|
|
}
|
|
|
|
/*
|
|
* Save stack trace to the given array of MAX_TRACE size.
|
|
*/
|
|
static int __save_stack_trace(unsigned long *trace)
|
|
{
|
|
struct stack_trace stack_trace;
|
|
|
|
stack_trace.max_entries = MAX_TRACE;
|
|
stack_trace.nr_entries = 0;
|
|
stack_trace.entries = trace;
|
|
stack_trace.skip = 2;
|
|
save_stack_trace(&stack_trace);
|
|
|
|
return stack_trace.nr_entries;
|
|
}
|
|
|
|
/*
|
|
* Create the metadata (struct kmemleak_object) corresponding to an allocated
|
|
* memory block and add it to the object_list and object_tree_root.
|
|
*/
|
|
static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
|
|
int min_count, gfp_t gfp)
|
|
{
|
|
unsigned long flags;
|
|
struct kmemleak_object *object;
|
|
struct prio_tree_node *node;
|
|
|
|
object = kmem_cache_alloc(object_cache, gfp & GFP_KMEMLEAK_MASK);
|
|
if (!object) {
|
|
kmemleak_stop("Cannot allocate a kmemleak_object structure\n");
|
|
return NULL;
|
|
}
|
|
|
|
INIT_LIST_HEAD(&object->object_list);
|
|
INIT_LIST_HEAD(&object->gray_list);
|
|
INIT_HLIST_HEAD(&object->area_list);
|
|
spin_lock_init(&object->lock);
|
|
atomic_set(&object->use_count, 1);
|
|
object->flags = OBJECT_ALLOCATED | OBJECT_NEW;
|
|
object->pointer = ptr;
|
|
object->size = size;
|
|
object->min_count = min_count;
|
|
object->count = -1; /* no color initially */
|
|
object->jiffies = jiffies;
|
|
|
|
/* task information */
|
|
if (in_irq()) {
|
|
object->pid = 0;
|
|
strncpy(object->comm, "hardirq", sizeof(object->comm));
|
|
} else if (in_softirq()) {
|
|
object->pid = 0;
|
|
strncpy(object->comm, "softirq", sizeof(object->comm));
|
|
} else {
|
|
object->pid = current->pid;
|
|
/*
|
|
* There is a small chance of a race with set_task_comm(),
|
|
* however using get_task_comm() here may cause locking
|
|
* dependency issues with current->alloc_lock. In the worst
|
|
* case, the command line is not correct.
|
|
*/
|
|
strncpy(object->comm, current->comm, sizeof(object->comm));
|
|
}
|
|
|
|
/* kernel backtrace */
|
|
object->trace_len = __save_stack_trace(object->trace);
|
|
|
|
INIT_PRIO_TREE_NODE(&object->tree_node);
|
|
object->tree_node.start = ptr;
|
|
object->tree_node.last = ptr + size - 1;
|
|
|
|
write_lock_irqsave(&kmemleak_lock, flags);
|
|
|
|
min_addr = min(min_addr, ptr);
|
|
max_addr = max(max_addr, ptr + size);
|
|
node = prio_tree_insert(&object_tree_root, &object->tree_node);
|
|
/*
|
|
* The code calling the kernel does not yet have the pointer to the
|
|
* memory block to be able to free it. However, we still hold the
|
|
* kmemleak_lock here in case parts of the kernel started freeing
|
|
* random memory blocks.
|
|
*/
|
|
if (node != &object->tree_node) {
|
|
kmemleak_stop("Cannot insert 0x%lx into the object search tree "
|
|
"(already existing)\n", ptr);
|
|
object = lookup_object(ptr, 1);
|
|
spin_lock(&object->lock);
|
|
dump_object_info(object);
|
|
spin_unlock(&object->lock);
|
|
|
|
goto out;
|
|
}
|
|
list_add_tail_rcu(&object->object_list, &object_list);
|
|
out:
|
|
write_unlock_irqrestore(&kmemleak_lock, flags);
|
|
return object;
|
|
}
|
|
|
|
/*
|
|
* Remove the metadata (struct kmemleak_object) for a memory block from the
|
|
* object_list and object_tree_root and decrement its use_count.
|
|
*/
|
|
static void __delete_object(struct kmemleak_object *object)
|
|
{
|
|
unsigned long flags;
|
|
|
|
write_lock_irqsave(&kmemleak_lock, flags);
|
|
prio_tree_remove(&object_tree_root, &object->tree_node);
|
|
list_del_rcu(&object->object_list);
|
|
write_unlock_irqrestore(&kmemleak_lock, flags);
|
|
|
|
WARN_ON(!(object->flags & OBJECT_ALLOCATED));
|
|
WARN_ON(atomic_read(&object->use_count) < 2);
|
|
|
|
/*
|
|
* Locking here also ensures that the corresponding memory block
|
|
* cannot be freed when it is being scanned.
|
|
*/
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
object->flags &= ~OBJECT_ALLOCATED;
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
put_object(object);
|
|
}
|
|
|
|
/*
|
|
* Look up the metadata (struct kmemleak_object) corresponding to ptr and
|
|
* delete it.
|
|
*/
|
|
static void delete_object_full(unsigned long ptr)
|
|
{
|
|
struct kmemleak_object *object;
|
|
|
|
object = find_and_get_object(ptr, 0);
|
|
if (!object) {
|
|
#ifdef DEBUG
|
|
kmemleak_warn("Freeing unknown object at 0x%08lx\n",
|
|
ptr);
|
|
#endif
|
|
return;
|
|
}
|
|
__delete_object(object);
|
|
put_object(object);
|
|
}
|
|
|
|
/*
|
|
* Look up the metadata (struct kmemleak_object) corresponding to ptr and
|
|
* delete it. If the memory block is partially freed, the function may create
|
|
* additional metadata for the remaining parts of the block.
|
|
*/
|
|
static void delete_object_part(unsigned long ptr, size_t size)
|
|
{
|
|
struct kmemleak_object *object;
|
|
unsigned long start, end;
|
|
|
|
object = find_and_get_object(ptr, 1);
|
|
if (!object) {
|
|
#ifdef DEBUG
|
|
kmemleak_warn("Partially freeing unknown object at 0x%08lx "
|
|
"(size %zu)\n", ptr, size);
|
|
#endif
|
|
return;
|
|
}
|
|
__delete_object(object);
|
|
|
|
/*
|
|
* Create one or two objects that may result from the memory block
|
|
* split. Note that partial freeing is only done by free_bootmem() and
|
|
* this happens before kmemleak_init() is called. The path below is
|
|
* only executed during early log recording in kmemleak_init(), so
|
|
* GFP_KERNEL is enough.
|
|
*/
|
|
start = object->pointer;
|
|
end = object->pointer + object->size;
|
|
if (ptr > start)
|
|
create_object(start, ptr - start, object->min_count,
|
|
GFP_KERNEL);
|
|
if (ptr + size < end)
|
|
create_object(ptr + size, end - ptr - size, object->min_count,
|
|
GFP_KERNEL);
|
|
|
|
put_object(object);
|
|
}
|
|
|
|
static void __paint_it(struct kmemleak_object *object, int color)
|
|
{
|
|
object->min_count = color;
|
|
if (color == KMEMLEAK_BLACK)
|
|
object->flags |= OBJECT_NO_SCAN;
|
|
}
|
|
|
|
static void paint_it(struct kmemleak_object *object, int color)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
__paint_it(object, color);
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
}
|
|
|
|
static void paint_ptr(unsigned long ptr, int color)
|
|
{
|
|
struct kmemleak_object *object;
|
|
|
|
object = find_and_get_object(ptr, 0);
|
|
if (!object) {
|
|
kmemleak_warn("Trying to color unknown object "
|
|
"at 0x%08lx as %s\n", ptr,
|
|
(color == KMEMLEAK_GREY) ? "Grey" :
|
|
(color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
|
|
return;
|
|
}
|
|
paint_it(object, color);
|
|
put_object(object);
|
|
}
|
|
|
|
/*
|
|
* Make a object permanently as gray-colored so that it can no longer be
|
|
* reported as a leak. This is used in general to mark a false positive.
|
|
*/
|
|
static void make_gray_object(unsigned long ptr)
|
|
{
|
|
paint_ptr(ptr, KMEMLEAK_GREY);
|
|
}
|
|
|
|
/*
|
|
* Mark the object as black-colored so that it is ignored from scans and
|
|
* reporting.
|
|
*/
|
|
static void make_black_object(unsigned long ptr)
|
|
{
|
|
paint_ptr(ptr, KMEMLEAK_BLACK);
|
|
}
|
|
|
|
/*
|
|
* Add a scanning area to the object. If at least one such area is added,
|
|
* kmemleak will only scan these ranges rather than the whole memory block.
|
|
*/
|
|
static void add_scan_area(unsigned long ptr, unsigned long offset,
|
|
size_t length, gfp_t gfp)
|
|
{
|
|
unsigned long flags;
|
|
struct kmemleak_object *object;
|
|
struct kmemleak_scan_area *area;
|
|
|
|
object = find_and_get_object(ptr, 0);
|
|
if (!object) {
|
|
kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
|
|
ptr);
|
|
return;
|
|
}
|
|
|
|
area = kmem_cache_alloc(scan_area_cache, gfp & GFP_KMEMLEAK_MASK);
|
|
if (!area) {
|
|
kmemleak_warn("Cannot allocate a scan area\n");
|
|
goto out;
|
|
}
|
|
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
if (offset + length > object->size) {
|
|
kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
|
|
dump_object_info(object);
|
|
kmem_cache_free(scan_area_cache, area);
|
|
goto out_unlock;
|
|
}
|
|
|
|
INIT_HLIST_NODE(&area->node);
|
|
area->offset = offset;
|
|
area->length = length;
|
|
|
|
hlist_add_head(&area->node, &object->area_list);
|
|
out_unlock:
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
out:
|
|
put_object(object);
|
|
}
|
|
|
|
/*
|
|
* Set the OBJECT_NO_SCAN flag for the object corresponding to the give
|
|
* pointer. Such object will not be scanned by kmemleak but references to it
|
|
* are searched.
|
|
*/
|
|
static void object_no_scan(unsigned long ptr)
|
|
{
|
|
unsigned long flags;
|
|
struct kmemleak_object *object;
|
|
|
|
object = find_and_get_object(ptr, 0);
|
|
if (!object) {
|
|
kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
|
|
return;
|
|
}
|
|
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
object->flags |= OBJECT_NO_SCAN;
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
put_object(object);
|
|
}
|
|
|
|
/*
|
|
* Log an early kmemleak_* call to the early_log buffer. These calls will be
|
|
* processed later once kmemleak is fully initialized.
|
|
*/
|
|
static void __init log_early(int op_type, const void *ptr, size_t size,
|
|
int min_count, unsigned long offset, size_t length)
|
|
{
|
|
unsigned long flags;
|
|
struct early_log *log;
|
|
|
|
if (crt_early_log >= ARRAY_SIZE(early_log)) {
|
|
pr_warning("Early log buffer exceeded, "
|
|
"please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
|
|
kmemleak_disable();
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* There is no need for locking since the kernel is still in UP mode
|
|
* at this stage. Disabling the IRQs is enough.
|
|
*/
|
|
local_irq_save(flags);
|
|
log = &early_log[crt_early_log];
|
|
log->op_type = op_type;
|
|
log->ptr = ptr;
|
|
log->size = size;
|
|
log->min_count = min_count;
|
|
log->offset = offset;
|
|
log->length = length;
|
|
if (op_type == KMEMLEAK_ALLOC)
|
|
log->trace_len = __save_stack_trace(log->trace);
|
|
crt_early_log++;
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
/*
|
|
* Log an early allocated block and populate the stack trace.
|
|
*/
|
|
static void early_alloc(struct early_log *log)
|
|
{
|
|
struct kmemleak_object *object;
|
|
unsigned long flags;
|
|
int i;
|
|
|
|
if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
|
|
return;
|
|
|
|
/*
|
|
* RCU locking needed to ensure object is not freed via put_object().
|
|
*/
|
|
rcu_read_lock();
|
|
object = create_object((unsigned long)log->ptr, log->size,
|
|
log->min_count, GFP_ATOMIC);
|
|
if (!object)
|
|
goto out;
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
for (i = 0; i < log->trace_len; i++)
|
|
object->trace[i] = log->trace[i];
|
|
object->trace_len = log->trace_len;
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
out:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* Memory allocation function callback. This function is called from the
|
|
* kernel allocators when a new block is allocated (kmem_cache_alloc, kmalloc,
|
|
* vmalloc etc.).
|
|
*/
|
|
void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
|
|
gfp_t gfp)
|
|
{
|
|
pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
|
|
|
|
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
create_object((unsigned long)ptr, size, min_count, gfp);
|
|
else if (atomic_read(&kmemleak_early_log))
|
|
log_early(KMEMLEAK_ALLOC, ptr, size, min_count, 0, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmemleak_alloc);
|
|
|
|
/*
|
|
* Memory freeing function callback. This function is called from the kernel
|
|
* allocators when a block is freed (kmem_cache_free, kfree, vfree etc.).
|
|
*/
|
|
void __ref kmemleak_free(const void *ptr)
|
|
{
|
|
pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
|
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
delete_object_full((unsigned long)ptr);
|
|
else if (atomic_read(&kmemleak_early_log))
|
|
log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmemleak_free);
|
|
|
|
/*
|
|
* Partial memory freeing function callback. This function is usually called
|
|
* from bootmem allocator when (part of) a memory block is freed.
|
|
*/
|
|
void __ref kmemleak_free_part(const void *ptr, size_t size)
|
|
{
|
|
pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
|
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
delete_object_part((unsigned long)ptr, size);
|
|
else if (atomic_read(&kmemleak_early_log))
|
|
log_early(KMEMLEAK_FREE_PART, ptr, size, 0, 0, 0);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kmemleak_free_part);
|
|
|
|
/*
|
|
* Mark an already allocated memory block as a false positive. This will cause
|
|
* the block to no longer be reported as leak and always be scanned.
|
|
*/
|
|
void __ref kmemleak_not_leak(const void *ptr)
|
|
{
|
|
pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
|
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
make_gray_object((unsigned long)ptr);
|
|
else if (atomic_read(&kmemleak_early_log))
|
|
log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0, 0, 0);
|
|
}
|
|
EXPORT_SYMBOL(kmemleak_not_leak);
|
|
|
|
/*
|
|
* Ignore a memory block. This is usually done when it is known that the
|
|
* corresponding block is not a leak and does not contain any references to
|
|
* other allocated memory blocks.
|
|
*/
|
|
void __ref kmemleak_ignore(const void *ptr)
|
|
{
|
|
pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
|
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
make_black_object((unsigned long)ptr);
|
|
else if (atomic_read(&kmemleak_early_log))
|
|
log_early(KMEMLEAK_IGNORE, ptr, 0, 0, 0, 0);
|
|
}
|
|
EXPORT_SYMBOL(kmemleak_ignore);
|
|
|
|
/*
|
|
* Limit the range to be scanned in an allocated memory block.
|
|
*/
|
|
void __ref kmemleak_scan_area(const void *ptr, unsigned long offset,
|
|
size_t length, gfp_t gfp)
|
|
{
|
|
pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
|
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
add_scan_area((unsigned long)ptr, offset, length, gfp);
|
|
else if (atomic_read(&kmemleak_early_log))
|
|
log_early(KMEMLEAK_SCAN_AREA, ptr, 0, 0, offset, length);
|
|
}
|
|
EXPORT_SYMBOL(kmemleak_scan_area);
|
|
|
|
/*
|
|
* Inform kmemleak not to scan the given memory block.
|
|
*/
|
|
void __ref kmemleak_no_scan(const void *ptr)
|
|
{
|
|
pr_debug("%s(0x%p)\n", __func__, ptr);
|
|
|
|
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
|
|
object_no_scan((unsigned long)ptr);
|
|
else if (atomic_read(&kmemleak_early_log))
|
|
log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0, 0, 0);
|
|
}
|
|
EXPORT_SYMBOL(kmemleak_no_scan);
|
|
|
|
/*
|
|
* Memory scanning is a long process and it needs to be interruptable. This
|
|
* function checks whether such interrupt condition occured.
|
|
*/
|
|
static int scan_should_stop(void)
|
|
{
|
|
if (!atomic_read(&kmemleak_enabled))
|
|
return 1;
|
|
|
|
/*
|
|
* This function may be called from either process or kthread context,
|
|
* hence the need to check for both stop conditions.
|
|
*/
|
|
if (current->mm)
|
|
return signal_pending(current);
|
|
else
|
|
return kthread_should_stop();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Scan a memory block (exclusive range) for valid pointers and add those
|
|
* found to the gray list.
|
|
*/
|
|
static void scan_block(void *_start, void *_end,
|
|
struct kmemleak_object *scanned, int allow_resched)
|
|
{
|
|
unsigned long *ptr;
|
|
unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
|
|
unsigned long *end = _end - (BYTES_PER_POINTER - 1);
|
|
|
|
for (ptr = start; ptr < end; ptr++) {
|
|
struct kmemleak_object *object;
|
|
unsigned long flags;
|
|
unsigned long pointer;
|
|
|
|
if (allow_resched)
|
|
cond_resched();
|
|
if (scan_should_stop())
|
|
break;
|
|
|
|
/* don't scan uninitialized memory */
|
|
if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
|
|
BYTES_PER_POINTER))
|
|
continue;
|
|
|
|
pointer = *ptr;
|
|
|
|
object = find_and_get_object(pointer, 1);
|
|
if (!object)
|
|
continue;
|
|
if (object == scanned) {
|
|
/* self referenced, ignore */
|
|
put_object(object);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Avoid the lockdep recursive warning on object->lock being
|
|
* previously acquired in scan_object(). These locks are
|
|
* enclosed by scan_mutex.
|
|
*/
|
|
spin_lock_irqsave_nested(&object->lock, flags,
|
|
SINGLE_DEPTH_NESTING);
|
|
if (!color_white(object)) {
|
|
/* non-orphan, ignored or new */
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
put_object(object);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Increase the object's reference count (number of pointers
|
|
* to the memory block). If this count reaches the required
|
|
* minimum, the object's color will become gray and it will be
|
|
* added to the gray_list.
|
|
*/
|
|
object->count++;
|
|
if (color_gray(object))
|
|
list_add_tail(&object->gray_list, &gray_list);
|
|
else
|
|
put_object(object);
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Scan a memory block corresponding to a kmemleak_object. A condition is
|
|
* that object->use_count >= 1.
|
|
*/
|
|
static void scan_object(struct kmemleak_object *object)
|
|
{
|
|
struct kmemleak_scan_area *area;
|
|
struct hlist_node *elem;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* Once the object->lock is aquired, the corresponding memory block
|
|
* cannot be freed (the same lock is aquired in delete_object).
|
|
*/
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
if (object->flags & OBJECT_NO_SCAN)
|
|
goto out;
|
|
if (!(object->flags & OBJECT_ALLOCATED))
|
|
/* already freed object */
|
|
goto out;
|
|
if (hlist_empty(&object->area_list)) {
|
|
void *start = (void *)object->pointer;
|
|
void *end = (void *)(object->pointer + object->size);
|
|
|
|
while (start < end && (object->flags & OBJECT_ALLOCATED) &&
|
|
!(object->flags & OBJECT_NO_SCAN)) {
|
|
scan_block(start, min(start + MAX_SCAN_SIZE, end),
|
|
object, 0);
|
|
start += MAX_SCAN_SIZE;
|
|
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
cond_resched();
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
}
|
|
} else
|
|
hlist_for_each_entry(area, elem, &object->area_list, node)
|
|
scan_block((void *)(object->pointer + area->offset),
|
|
(void *)(object->pointer + area->offset
|
|
+ area->length), object, 0);
|
|
out:
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
}
|
|
|
|
/*
|
|
* Scan data sections and all the referenced memory blocks allocated via the
|
|
* kernel's standard allocators. This function must be called with the
|
|
* scan_mutex held.
|
|
*/
|
|
static void kmemleak_scan(void)
|
|
{
|
|
unsigned long flags;
|
|
struct kmemleak_object *object, *tmp;
|
|
int i;
|
|
int new_leaks = 0;
|
|
int gray_list_pass = 0;
|
|
|
|
jiffies_last_scan = jiffies;
|
|
|
|
/* prepare the kmemleak_object's */
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(object, &object_list, object_list) {
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
#ifdef DEBUG
|
|
/*
|
|
* With a few exceptions there should be a maximum of
|
|
* 1 reference to any object at this point.
|
|
*/
|
|
if (atomic_read(&object->use_count) > 1) {
|
|
pr_debug("object->use_count = %d\n",
|
|
atomic_read(&object->use_count));
|
|
dump_object_info(object);
|
|
}
|
|
#endif
|
|
/* reset the reference count (whiten the object) */
|
|
object->count = 0;
|
|
object->flags &= ~OBJECT_NEW;
|
|
if (color_gray(object) && get_object(object))
|
|
list_add_tail(&object->gray_list, &gray_list);
|
|
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/* data/bss scanning */
|
|
scan_block(_sdata, _edata, NULL, 1);
|
|
scan_block(__bss_start, __bss_stop, NULL, 1);
|
|
|
|
#ifdef CONFIG_SMP
|
|
/* per-cpu sections scanning */
|
|
for_each_possible_cpu(i)
|
|
scan_block(__per_cpu_start + per_cpu_offset(i),
|
|
__per_cpu_end + per_cpu_offset(i), NULL, 1);
|
|
#endif
|
|
|
|
/*
|
|
* Struct page scanning for each node. The code below is not yet safe
|
|
* with MEMORY_HOTPLUG.
|
|
*/
|
|
for_each_online_node(i) {
|
|
pg_data_t *pgdat = NODE_DATA(i);
|
|
unsigned long start_pfn = pgdat->node_start_pfn;
|
|
unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
|
|
unsigned long pfn;
|
|
|
|
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
|
|
struct page *page;
|
|
|
|
if (!pfn_valid(pfn))
|
|
continue;
|
|
page = pfn_to_page(pfn);
|
|
/* only scan if page is in use */
|
|
if (page_count(page) == 0)
|
|
continue;
|
|
scan_block(page, page + 1, NULL, 1);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Scanning the task stacks (may introduce false negatives).
|
|
*/
|
|
if (kmemleak_stack_scan) {
|
|
struct task_struct *p, *g;
|
|
|
|
read_lock(&tasklist_lock);
|
|
do_each_thread(g, p) {
|
|
scan_block(task_stack_page(p), task_stack_page(p) +
|
|
THREAD_SIZE, NULL, 0);
|
|
} while_each_thread(g, p);
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
/*
|
|
* Scan the objects already referenced from the sections scanned
|
|
* above. More objects will be referenced and, if there are no memory
|
|
* leaks, all the objects will be scanned. The list traversal is safe
|
|
* for both tail additions and removals from inside the loop. The
|
|
* kmemleak objects cannot be freed from outside the loop because their
|
|
* use_count was increased.
|
|
*/
|
|
repeat:
|
|
object = list_entry(gray_list.next, typeof(*object), gray_list);
|
|
while (&object->gray_list != &gray_list) {
|
|
cond_resched();
|
|
|
|
/* may add new objects to the list */
|
|
if (!scan_should_stop())
|
|
scan_object(object);
|
|
|
|
tmp = list_entry(object->gray_list.next, typeof(*object),
|
|
gray_list);
|
|
|
|
/* remove the object from the list and release it */
|
|
list_del(&object->gray_list);
|
|
put_object(object);
|
|
|
|
object = tmp;
|
|
}
|
|
|
|
if (scan_should_stop() || ++gray_list_pass >= GRAY_LIST_PASSES)
|
|
goto scan_end;
|
|
|
|
/*
|
|
* Check for new objects allocated during this scanning and add them
|
|
* to the gray list.
|
|
*/
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(object, &object_list, object_list) {
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
if ((object->flags & OBJECT_NEW) && !color_black(object) &&
|
|
get_object(object)) {
|
|
object->flags &= ~OBJECT_NEW;
|
|
list_add_tail(&object->gray_list, &gray_list);
|
|
}
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
if (!list_empty(&gray_list))
|
|
goto repeat;
|
|
|
|
scan_end:
|
|
WARN_ON(!list_empty(&gray_list));
|
|
|
|
/*
|
|
* If scanning was stopped or new objects were being allocated at a
|
|
* higher rate than gray list scanning, do not report any new
|
|
* unreferenced objects.
|
|
*/
|
|
if (scan_should_stop() || gray_list_pass >= GRAY_LIST_PASSES)
|
|
return;
|
|
|
|
/*
|
|
* Scanning result reporting.
|
|
*/
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(object, &object_list, object_list) {
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
if (unreferenced_object(object) &&
|
|
!(object->flags & OBJECT_REPORTED)) {
|
|
object->flags |= OBJECT_REPORTED;
|
|
new_leaks++;
|
|
}
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
if (new_leaks)
|
|
pr_info("%d new suspected memory leaks (see "
|
|
"/sys/kernel/debug/kmemleak)\n", new_leaks);
|
|
|
|
}
|
|
|
|
/*
|
|
* Thread function performing automatic memory scanning. Unreferenced objects
|
|
* at the end of a memory scan are reported but only the first time.
|
|
*/
|
|
static int kmemleak_scan_thread(void *arg)
|
|
{
|
|
static int first_run = 1;
|
|
|
|
pr_info("Automatic memory scanning thread started\n");
|
|
set_user_nice(current, 10);
|
|
|
|
/*
|
|
* Wait before the first scan to allow the system to fully initialize.
|
|
*/
|
|
if (first_run) {
|
|
first_run = 0;
|
|
ssleep(SECS_FIRST_SCAN);
|
|
}
|
|
|
|
while (!kthread_should_stop()) {
|
|
signed long timeout = jiffies_scan_wait;
|
|
|
|
mutex_lock(&scan_mutex);
|
|
kmemleak_scan();
|
|
mutex_unlock(&scan_mutex);
|
|
|
|
/* wait before the next scan */
|
|
while (timeout && !kthread_should_stop())
|
|
timeout = schedule_timeout_interruptible(timeout);
|
|
}
|
|
|
|
pr_info("Automatic memory scanning thread ended\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Start the automatic memory scanning thread. This function must be called
|
|
* with the scan_mutex held.
|
|
*/
|
|
static void start_scan_thread(void)
|
|
{
|
|
if (scan_thread)
|
|
return;
|
|
scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
|
|
if (IS_ERR(scan_thread)) {
|
|
pr_warning("Failed to create the scan thread\n");
|
|
scan_thread = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Stop the automatic memory scanning thread. This function must be called
|
|
* with the scan_mutex held.
|
|
*/
|
|
static void stop_scan_thread(void)
|
|
{
|
|
if (scan_thread) {
|
|
kthread_stop(scan_thread);
|
|
scan_thread = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Iterate over the object_list and return the first valid object at or after
|
|
* the required position with its use_count incremented. The function triggers
|
|
* a memory scanning when the pos argument points to the first position.
|
|
*/
|
|
static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
|
|
{
|
|
struct kmemleak_object *object;
|
|
loff_t n = *pos;
|
|
int err;
|
|
|
|
err = mutex_lock_interruptible(&scan_mutex);
|
|
if (err < 0)
|
|
return ERR_PTR(err);
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(object, &object_list, object_list) {
|
|
if (n-- > 0)
|
|
continue;
|
|
if (get_object(object))
|
|
goto out;
|
|
}
|
|
object = NULL;
|
|
out:
|
|
return object;
|
|
}
|
|
|
|
/*
|
|
* Return the next object in the object_list. The function decrements the
|
|
* use_count of the previous object and increases that of the next one.
|
|
*/
|
|
static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
|
|
{
|
|
struct kmemleak_object *prev_obj = v;
|
|
struct kmemleak_object *next_obj = NULL;
|
|
struct list_head *n = &prev_obj->object_list;
|
|
|
|
++(*pos);
|
|
|
|
list_for_each_continue_rcu(n, &object_list) {
|
|
next_obj = list_entry(n, struct kmemleak_object, object_list);
|
|
if (get_object(next_obj))
|
|
break;
|
|
}
|
|
|
|
put_object(prev_obj);
|
|
return next_obj;
|
|
}
|
|
|
|
/*
|
|
* Decrement the use_count of the last object required, if any.
|
|
*/
|
|
static void kmemleak_seq_stop(struct seq_file *seq, void *v)
|
|
{
|
|
if (!IS_ERR(v)) {
|
|
/*
|
|
* kmemleak_seq_start may return ERR_PTR if the scan_mutex
|
|
* waiting was interrupted, so only release it if !IS_ERR.
|
|
*/
|
|
rcu_read_unlock();
|
|
mutex_unlock(&scan_mutex);
|
|
if (v)
|
|
put_object(v);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Print the information for an unreferenced object to the seq file.
|
|
*/
|
|
static int kmemleak_seq_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct kmemleak_object *object = v;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
|
|
print_unreferenced(seq, object);
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
return 0;
|
|
}
|
|
|
|
static const struct seq_operations kmemleak_seq_ops = {
|
|
.start = kmemleak_seq_start,
|
|
.next = kmemleak_seq_next,
|
|
.stop = kmemleak_seq_stop,
|
|
.show = kmemleak_seq_show,
|
|
};
|
|
|
|
static int kmemleak_open(struct inode *inode, struct file *file)
|
|
{
|
|
if (!atomic_read(&kmemleak_enabled))
|
|
return -EBUSY;
|
|
|
|
return seq_open(file, &kmemleak_seq_ops);
|
|
}
|
|
|
|
static int kmemleak_release(struct inode *inode, struct file *file)
|
|
{
|
|
return seq_release(inode, file);
|
|
}
|
|
|
|
static int dump_str_object_info(const char *str)
|
|
{
|
|
unsigned long flags;
|
|
struct kmemleak_object *object;
|
|
unsigned long addr;
|
|
|
|
addr= simple_strtoul(str, NULL, 0);
|
|
object = find_and_get_object(addr, 0);
|
|
if (!object) {
|
|
pr_info("Unknown object at 0x%08lx\n", addr);
|
|
return -EINVAL;
|
|
}
|
|
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
dump_object_info(object);
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
|
|
put_object(object);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* We use grey instead of black to ensure we can do future scans on the same
|
|
* objects. If we did not do future scans these black objects could
|
|
* potentially contain references to newly allocated objects in the future and
|
|
* we'd end up with false positives.
|
|
*/
|
|
static void kmemleak_clear(void)
|
|
{
|
|
struct kmemleak_object *object;
|
|
unsigned long flags;
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(object, &object_list, object_list) {
|
|
spin_lock_irqsave(&object->lock, flags);
|
|
if ((object->flags & OBJECT_REPORTED) &&
|
|
unreferenced_object(object))
|
|
__paint_it(object, KMEMLEAK_GREY);
|
|
spin_unlock_irqrestore(&object->lock, flags);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* File write operation to configure kmemleak at run-time. The following
|
|
* commands can be written to the /sys/kernel/debug/kmemleak file:
|
|
* off - disable kmemleak (irreversible)
|
|
* stack=on - enable the task stacks scanning
|
|
* stack=off - disable the tasks stacks scanning
|
|
* scan=on - start the automatic memory scanning thread
|
|
* scan=off - stop the automatic memory scanning thread
|
|
* scan=... - set the automatic memory scanning period in seconds (0 to
|
|
* disable it)
|
|
* scan - trigger a memory scan
|
|
* clear - mark all current reported unreferenced kmemleak objects as
|
|
* grey to ignore printing them
|
|
* dump=... - dump information about the object found at the given address
|
|
*/
|
|
static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
|
|
size_t size, loff_t *ppos)
|
|
{
|
|
char buf[64];
|
|
int buf_size;
|
|
int ret;
|
|
|
|
buf_size = min(size, (sizeof(buf) - 1));
|
|
if (strncpy_from_user(buf, user_buf, buf_size) < 0)
|
|
return -EFAULT;
|
|
buf[buf_size] = 0;
|
|
|
|
ret = mutex_lock_interruptible(&scan_mutex);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
if (strncmp(buf, "off", 3) == 0)
|
|
kmemleak_disable();
|
|
else if (strncmp(buf, "stack=on", 8) == 0)
|
|
kmemleak_stack_scan = 1;
|
|
else if (strncmp(buf, "stack=off", 9) == 0)
|
|
kmemleak_stack_scan = 0;
|
|
else if (strncmp(buf, "scan=on", 7) == 0)
|
|
start_scan_thread();
|
|
else if (strncmp(buf, "scan=off", 8) == 0)
|
|
stop_scan_thread();
|
|
else if (strncmp(buf, "scan=", 5) == 0) {
|
|
unsigned long secs;
|
|
|
|
ret = strict_strtoul(buf + 5, 0, &secs);
|
|
if (ret < 0)
|
|
goto out;
|
|
stop_scan_thread();
|
|
if (secs) {
|
|
jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
|
|
start_scan_thread();
|
|
}
|
|
} else if (strncmp(buf, "scan", 4) == 0)
|
|
kmemleak_scan();
|
|
else if (strncmp(buf, "clear", 5) == 0)
|
|
kmemleak_clear();
|
|
else if (strncmp(buf, "dump=", 5) == 0)
|
|
ret = dump_str_object_info(buf + 5);
|
|
else
|
|
ret = -EINVAL;
|
|
|
|
out:
|
|
mutex_unlock(&scan_mutex);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
/* ignore the rest of the buffer, only one command at a time */
|
|
*ppos += size;
|
|
return size;
|
|
}
|
|
|
|
static const struct file_operations kmemleak_fops = {
|
|
.owner = THIS_MODULE,
|
|
.open = kmemleak_open,
|
|
.read = seq_read,
|
|
.write = kmemleak_write,
|
|
.llseek = seq_lseek,
|
|
.release = kmemleak_release,
|
|
};
|
|
|
|
/*
|
|
* Perform the freeing of the kmemleak internal objects after waiting for any
|
|
* current memory scan to complete.
|
|
*/
|
|
static void kmemleak_do_cleanup(struct work_struct *work)
|
|
{
|
|
struct kmemleak_object *object;
|
|
|
|
mutex_lock(&scan_mutex);
|
|
stop_scan_thread();
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(object, &object_list, object_list)
|
|
delete_object_full(object->pointer);
|
|
rcu_read_unlock();
|
|
mutex_unlock(&scan_mutex);
|
|
}
|
|
|
|
static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
|
|
|
|
/*
|
|
* Disable kmemleak. No memory allocation/freeing will be traced once this
|
|
* function is called. Disabling kmemleak is an irreversible operation.
|
|
*/
|
|
static void kmemleak_disable(void)
|
|
{
|
|
/* atomically check whether it was already invoked */
|
|
if (atomic_cmpxchg(&kmemleak_error, 0, 1))
|
|
return;
|
|
|
|
/* stop any memory operation tracing */
|
|
atomic_set(&kmemleak_early_log, 0);
|
|
atomic_set(&kmemleak_enabled, 0);
|
|
|
|
/* check whether it is too early for a kernel thread */
|
|
if (atomic_read(&kmemleak_initialized))
|
|
schedule_work(&cleanup_work);
|
|
|
|
pr_info("Kernel memory leak detector disabled\n");
|
|
}
|
|
|
|
/*
|
|
* Allow boot-time kmemleak disabling (enabled by default).
|
|
*/
|
|
static int kmemleak_boot_config(char *str)
|
|
{
|
|
if (!str)
|
|
return -EINVAL;
|
|
if (strcmp(str, "off") == 0)
|
|
kmemleak_disable();
|
|
else if (strcmp(str, "on") != 0)
|
|
return -EINVAL;
|
|
return 0;
|
|
}
|
|
early_param("kmemleak", kmemleak_boot_config);
|
|
|
|
/*
|
|
* Kmemleak initialization.
|
|
*/
|
|
void __init kmemleak_init(void)
|
|
{
|
|
int i;
|
|
unsigned long flags;
|
|
|
|
jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
|
|
jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
|
|
|
|
object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
|
|
scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
|
|
INIT_PRIO_TREE_ROOT(&object_tree_root);
|
|
|
|
/* the kernel is still in UP mode, so disabling the IRQs is enough */
|
|
local_irq_save(flags);
|
|
if (!atomic_read(&kmemleak_error)) {
|
|
atomic_set(&kmemleak_enabled, 1);
|
|
atomic_set(&kmemleak_early_log, 0);
|
|
}
|
|
local_irq_restore(flags);
|
|
|
|
/*
|
|
* This is the point where tracking allocations is safe. Automatic
|
|
* scanning is started during the late initcall. Add the early logged
|
|
* callbacks to the kmemleak infrastructure.
|
|
*/
|
|
for (i = 0; i < crt_early_log; i++) {
|
|
struct early_log *log = &early_log[i];
|
|
|
|
switch (log->op_type) {
|
|
case KMEMLEAK_ALLOC:
|
|
early_alloc(log);
|
|
break;
|
|
case KMEMLEAK_FREE:
|
|
kmemleak_free(log->ptr);
|
|
break;
|
|
case KMEMLEAK_FREE_PART:
|
|
kmemleak_free_part(log->ptr, log->size);
|
|
break;
|
|
case KMEMLEAK_NOT_LEAK:
|
|
kmemleak_not_leak(log->ptr);
|
|
break;
|
|
case KMEMLEAK_IGNORE:
|
|
kmemleak_ignore(log->ptr);
|
|
break;
|
|
case KMEMLEAK_SCAN_AREA:
|
|
kmemleak_scan_area(log->ptr, log->offset, log->length,
|
|
GFP_KERNEL);
|
|
break;
|
|
case KMEMLEAK_NO_SCAN:
|
|
kmemleak_no_scan(log->ptr);
|
|
break;
|
|
default:
|
|
WARN_ON(1);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Late initialization function.
|
|
*/
|
|
static int __init kmemleak_late_init(void)
|
|
{
|
|
struct dentry *dentry;
|
|
|
|
atomic_set(&kmemleak_initialized, 1);
|
|
|
|
if (atomic_read(&kmemleak_error)) {
|
|
/*
|
|
* Some error occured and kmemleak was disabled. There is a
|
|
* small chance that kmemleak_disable() was called immediately
|
|
* after setting kmemleak_initialized and we may end up with
|
|
* two clean-up threads but serialized by scan_mutex.
|
|
*/
|
|
schedule_work(&cleanup_work);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
|
|
&kmemleak_fops);
|
|
if (!dentry)
|
|
pr_warning("Failed to create the debugfs kmemleak file\n");
|
|
mutex_lock(&scan_mutex);
|
|
start_scan_thread();
|
|
mutex_unlock(&scan_mutex);
|
|
|
|
pr_info("Kernel memory leak detector initialized\n");
|
|
|
|
return 0;
|
|
}
|
|
late_initcall(kmemleak_late_init);
|