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kasan: support use-after-scope detection

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Gcc revision 241896 implements use-after-scope detection.  Will be
available in gcc 7.  Support it in KASAN.

Gcc emits 2 new callbacks to poison/unpoison large stack objects when
they go in/out of scope.  Implement the callbacks and add a test.

[dvyukov@google.com: v3]
  Link: http://lkml.kernel.org/r/1479998292-144502-1-git-send-email-dvyukov@google.com
Link: http://lkml.kernel.org/r/1479226045-145148-1-git-send-email-dvyukov@google.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: <stable@vger.kernel.org>	[4.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dmitry Vyukov 2016-11-30 15:54:16 -08:00 committed by Linus Torvalds
parent 045d599a28
commit 828347f8f9
4 changed files with 52 additions and 0 deletions
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29
lib/test_kasan.c
View File

@ -20,6 +20,11 @@
#include <linux/uaccess.h>
#include <linux/module.h>
/*
* Note: test functions are marked noinline so that their names appear in
* reports.
*/
static noinline void __init kmalloc_oob_right(void)
{
char *ptr;
@ -411,6 +416,29 @@ static noinline void __init copy_user_test(void)
kfree(kmem);
}
static noinline void __init use_after_scope_test(void)
{
volatile char *volatile p;
pr_info("use-after-scope on int\n");
{
int local = 0;
p = (char *)&local;
}
p[0] = 1;
p[3] = 1;
pr_info("use-after-scope on array\n");
{
char local[1024] = {0};
p = local;
}
p[0] = 1;
p[1023] = 1;
}
static int __init kmalloc_tests_init(void)
{
kmalloc_oob_right();
@ -436,6 +464,7 @@ static int __init kmalloc_tests_init(void)
kasan_global_oob();
ksize_unpoisons_memory();
copy_user_test();
use_after_scope_test();
return -EAGAIN;
}

19
mm/kasan/kasan.c
View File

@ -764,6 +764,25 @@ EXPORT_SYMBOL(__asan_storeN_noabort);
void __asan_handle_no_return(void) {}
EXPORT_SYMBOL(__asan_handle_no_return);
/* Emitted by compiler to poison large objects when they go out of scope. */
void __asan_poison_stack_memory(const void *addr, size_t size)
{
/*
* Addr is KASAN_SHADOW_SCALE_SIZE-aligned and the object is surrounded
* by redzones, so we simply round up size to simplify logic.
*/
kasan_poison_shadow(addr, round_up(size, KASAN_SHADOW_SCALE_SIZE),
KASAN_USE_AFTER_SCOPE);
}
EXPORT_SYMBOL(__asan_poison_stack_memory);
/* Emitted by compiler to unpoison large objects when they go into scope. */
void __asan_unpoison_stack_memory(const void *addr, size_t size)
{
kasan_unpoison_shadow(addr, size);
}
EXPORT_SYMBOL(__asan_unpoison_stack_memory);
#ifdef CONFIG_MEMORY_HOTPLUG
static int kasan_mem_notifier(struct notifier_block *nb,
unsigned long action, void *data)

1
mm/kasan/kasan.h
View File

@ -21,6 +21,7 @@
#define KASAN_STACK_MID 0xF2
#define KASAN_STACK_RIGHT 0xF3
#define KASAN_STACK_PARTIAL 0xF4
#define KASAN_USE_AFTER_SCOPE 0xF8
/* Don't break randconfig/all*config builds */
#ifndef KASAN_ABI_VERSION

3
mm/kasan/report.c
View File

@ -90,6 +90,9 @@ static void print_error_description(struct kasan_access_info *info)
case KASAN_KMALLOC_FREE:
bug_type = "use-after-free";
break;
case KASAN_USE_AFTER_SCOPE:
bug_type = "use-after-scope";
break;
}
pr_err("BUG: KASAN: %s in %pS at addr %p\n",