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2b1be689f3
linux/kernel
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Matt Redfearn 2b1be689f3 printk/console: Always disable boot consoles that use init memory before it is freed 
Commit 4c30c6f566 ("kernel/printk: do not turn off bootconsole in
printk_late_init() if keep_bootcon") added a check on keep_bootcon to
ensure that boot consoles were kept around until the real console is
registered.

This can lead to problems if the boot console data and code are in the
init section, since it can be freed before the boot console is
unregistered.

Commit 81cc26f2bd ("printk: only unregister boot consoles when
necessary") fixed this a better way. It allowed to keep boot consoles
that did not use init data. Unfortunately it did not remove the check
of keep_bootcon.

This can lead to crashes and weird panics when the bootconsole is
accessed after free, especially if page poisoning is in use and the
code / data have been overwritten with a poison value.

To prevent this, always free the boot console if it is within the init
section. In addition, print a warning about that the console is removed
prematurely.

Finally there is a new comment how to avoid the warning. It replaced
an explanation that duplicated a more comprehensive function
description few lines above.

Fixes: 4c30c6f566 ("kernel/printk: do not turn off bootconsole in printk_late_init() if keep_bootcon")
Link: http://lkml.kernel.org/r/1500036673-7122-2-git-send-email-pmladek@suse.com
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: "Fabio M. Di Nitto" <fdinitto@redhat.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
[pmladek@suse.com: print the warning, code and comments clean up]
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
2017-07-27 15:04:21 +02:00
..
bpf bpf: prevent leaking pointer via xadd on unpriviledged 2017-06-29 15:44:34 -04:00
cgroup cpuset: consider dying css as offline 2017-05-24 12:43:30 -04:00
configs config: android-base: disable CONFIG_NFSD and CONFIG_NFS_FS 2017-06-09 11:47:38 +02:00
debug sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
events Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 18:08:06 -07:00
gcov gcov: support GCC 7.1 2017-05-12 15:57:15 -07:00
irq There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
livepatch livepatch: Fix stacking of patches with respect to RCU 2017-06-20 10:42:19 +02:00
locking There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
power Power management updates for v4.13-rc1 2017-07-04 13:39:41 -07:00
printk printk/console: Always disable boot consoles that use init memory before it is freed 2017-07-27 15:04:21 +02:00
rcu rcu: Remove RCU CPU stall warnings from Tiny RCU 2017-06-08 18:52:45 -07:00
sched Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 13:08:04 -07:00
time Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 16:14:51 -07:00
trace Merge branch 'for-4.13/block' of git://git.kernel.dk/linux-block 2017-07-03 10:34:51 -07:00
.gitignore
acct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
async.c async: Adjust system_state checks 2017-05-23 10:01:37 +02:00
audit_fsnotify.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
audit_tree.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
audit_watch.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
audit.c Merge branch 'stable-4.12' of git://git.infradead.org/users/pcmoore/audit 2017-05-03 09:21:59 -07:00
audit.h audit: Use timespec64 to represent audit timestamps 2017-05-02 10:16:05 -04:00
auditfilter.c audit: kernel generated netlink traffic should have a portid of 0 2017-05-02 10:16:05 -04:00
auditsc.c Merge branch 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-05-03 11:05:15 -07:00
backtracetest.c
bounds.c
capability.c capability: export has_capability 2017-01-12 07:01:56 -07:00
compat.c time: Move compat_gettimeofday()/settimeofday() to native 2017-06-14 00:00:46 +02:00
configs.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
context_tracking.c
cpu_pm.c
cpu.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 18:08:06 -07:00
crash_core.c ia64: reuse append_elf_note() and final_note() functions 2017-05-08 17:15:11 -07:00
crash_dump.c
cred.c doc: ReSTify credentials.txt 2017-05-18 10:30:19 -06:00
delayacct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
dma.c
elfcore.c
exec_domain.c
exit.c sched/core: Drop the unused try_get_task_struct() helper function 2017-06-20 12:48:37 +02:00
extable.c extable: Adjust system_state checks 2017-05-23 10:01:37 +02:00
fork.c Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-05-27 08:52:27 -07:00
freezer.c
futex_compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
futex.c There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
groups.c mm, vmalloc: use __GFP_HIGHMEM implicitly 2017-05-08 17:15:13 -07:00
hung_task.c kernel/hung_task.c: defer showing held locks 2017-05-08 17:15:10 -07:00
irq_work.c
jump_label.c jump_label: Reorder hotplug lock and jump_label_lock 2017-05-26 10:10:45 +02:00
kallsyms.c bpf: make jited programs visible in traces 2017-02-17 13:40:05 -05:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/mutex: Allow MUTEX_SPIN_ON_OWNER when DEBUG_MUTEXES 2016-10-25 11:31:51 +02:00
Kconfig.preempt
kcov.c kcov: simplify interrupt check 2017-05-08 17:15:12 -07:00
kexec_core.c objtool, x86: Add several functions and files to the objtool whitelist 2017-06-30 10:19:19 +02:00
kexec_file.c kexec, x86/purgatory: Unbreak it and clean it up 2017-03-10 20:55:09 +01:00
kexec_internal.h kexec, x86/purgatory: Unbreak it and clean it up 2017-03-10 20:55:09 +01:00
kexec.c
kmod.c sched/headers, vfs/execve: Prepare to move the do_execve*() prototypes from <linux/sched.h> to <linux/binfmts.h> 2017-03-02 08:42:39 +01:00
kprobes.c Merge branch 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 18:08:06 -07:00
ksysfs.c crash: move crashkernel parsing and vmcore related code under CONFIG_CRASH_CORE 2017-05-08 17:15:11 -07:00
kthread.c cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups 2017-03-17 10:18:47 -04:00
latencytop.c sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h> 2017-03-02 08:42:39 +01:00
Makefile crash: move crashkernel parsing and vmcore related code under CONFIG_CRASH_CORE 2017-05-08 17:15:11 -07:00
membarrier.c Fix: Disable sys_membarrier when nohz_full is enabled 2017-01-23 11:32:16 -08:00
memremap.c mm, zone_device: Replace {get, put}_zone_device_page() with a single reference to fix pmem crash 2017-05-01 09:15:53 +02:00
module_signing.c
module-internal.h
module.c kobject: support passing in variables for synthetic uevents 2017-05-25 18:30:51 +02:00
notifier.c kernel/notifier.c: simplify expression 2017-02-24 17:46:56 -08:00
nsproxy.c perf: Add PERF_RECORD_NAMESPACES to include namespaces related info 2017-03-13 15:57:41 -03:00
padata.c padata: Avoid nested calls to cpus_read_lock() in pcrypt_init_padata() 2017-05-26 10:10:37 +02:00
panic.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
params.c boot/param: Move next_arg() function to lib/cmdline.c for later reuse 2017-04-18 10:37:13 +02:00
pid_namespace.c pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes 2017-05-13 17:26:01 -05:00
pid.c pidns: disable pid allocation if pid_ns_prepare_proc() is failed in alloc_pid() 2017-05-08 17:15:12 -07:00
profile.c sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h> 2017-03-02 08:42:39 +01:00
ptrace.c ptrace: Properly initialize ptracer_cred on fork 2017-05-23 07:40:44 -05:00
range.c
reboot.c
relay.c Merge branch 'work.splice' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-02 11:38:06 -07:00
resource.c
seccomp.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
signal.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 16:14:51 -07:00
smp.c smp, cpumask: Use non-atomic cpumask_{set,clear}_cpu() 2017-05-23 10:01:32 +02:00
smpboot.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
smpboot.h
softirq.c sched/core: Remove 'task' parameter and rename tsk_restore_flags() to current_restore_flags() 2017-04-11 09:06:32 +02:00
stacktrace.c stacktrace/x86: add function for detecting reliable stack traces 2017-03-08 09:18:02 +01:00
stop_machine.c stop_machine: Provide stop_machine_cpuslocked() 2017-05-26 10:10:36 +02:00
sys_ni.c move aio compat to fs/aio.c 2016-12-22 22:58:37 -05:00
sys.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-05-05 11:08:43 -07:00
sysctl_binary.c sysctl: switch to use uuid_t 2017-06-05 16:59:15 +02:00
sysctl.c proc/sysctl: fix the int overflow for jiffies conversion 2017-05-08 17:15:10 -07:00
task_work.c
taskstats.c taskstats: add e/u/stime for TGID command 2017-05-08 17:15:12 -07:00
test_kprobes.c
torture.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/clock.h> 2017-03-02 08:42:27 +01:00
tracepoint.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
tsacct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
ucount.c ucount: Remove the atomicity from ucount->count 2017-03-06 15:26:37 -06:00
uid16.c sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
up.c
user_namespace.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h> 2017-03-02 08:42:29 +01:00
user-return-notifier.c
user.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/user.h> 2017-03-02 08:42:29 +01:00
utsname_sysctl.c sched/headers: Remove <linux/rwsem.h> from <linux/sched.h> 2017-03-03 01:45:36 +01:00
utsname.c sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
watchdog_hld.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
watchdog.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
workqueue_internal.h
workqueue.c sched/wait: Rename wait_queue_t => wait_queue_entry_t 2017-06-20 12:18:27 +02:00