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Commit 0d9e2632 authored by Aaron Tomlin's avatar Aaron Tomlin Committed by Ingo Molnar
Browse files

sched: Add default-disabled option to BUG() when stack end location is overwritten 



Currently in the event of a stack overrun a call to schedule()
does not check for this type of corruption. This corruption is
often silent and can go unnoticed. However once the corrupted
region is examined at a later stage, the outcome is undefined
and often results in a sporadic page fault which cannot be
handled.

This patch checks for a stack overrun and takes appropriate
action since the damage is already done, there is no point
in continuing.

Signed-off-by: default avatarAaron Tomlin <atomlin@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: dzickus@redhat.com
Cc: bmr@redhat.com
Cc: jcastillo@redhat.com
Cc: oleg@redhat.com
Cc: riel@redhat.com
Cc: prarit@redhat.com
Cc: jgh@redhat.com
Cc: minchan@kernel.org
Cc: mpe@ellerman.id.au
Cc: tglx@linutronix.de
Cc: rostedt@goodmis.org
Cc: hannes@cmpxchg.org
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lubomir Rintel <lkundrak@v3.sk>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1410527779-8133-4-git-send-email-atomlin@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a70857e4

kernel/sched/core.c

+3 −0
Original line number Diff line number Diff line
@@ -2693,6 +2693,9 @@ static noinline void __schedule_bug(struct task_struct *prev) 
 */

static inline void schedule_debug(struct task_struct *prev)

{

#ifdef CONFIG_SCHED_STACK_END_CHECK

	BUG_ON(unlikely(task_stack_end_corrupted(prev)));

#endif

	/*

	 * Test if we are atomic. Since do_exit() needs to call into

	 * schedule() atomically, we ignore that path. Otherwise whine

lib/Kconfig.debug

+12 −0
Original line number Diff line number Diff line
@@ -824,6 +824,18 @@ config SCHEDSTATS 
	  application, you can say N to avoid the very slight overhead

	  this adds.



config SCHED_STACK_END_CHECK

	bool "Detect stack corruption on calls to schedule()"

	depends on DEBUG_KERNEL

	default n

	help

	  This option checks for a stack overrun on calls to schedule().

	  If the stack end location is found to be over written always panic as

	  the content of the corrupted region can no longer be trusted.

	  This is to ensure no erroneous behaviour occurs which could result in

	  data corruption or a sporadic crash at a later stage once the region

	  is examined. The runtime overhead introduced is minimal.



config TIMER_STATS

	bool "Collect kernel timers statistics"

	depends on DEBUG_KERNEL && PROC_FS