[PATCH 2/2] sched: BUG when stack end location is over written

From: Aaron Tomlin
Date: Thu Sep 04 2014 - 10:53:03 EST

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

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: Aaron Tomlin <atomlin@xxxxxxxxxx>
kernel/sched/core.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ec1a286..d6af6a0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2660,6 +2660,9 @@ static noinline void __schedule_bug(struct task_struct *prev)
static inline void schedule_debug(struct task_struct *prev)
+ if (unlikely(prev != &init_task &&
+ task_stack_end_corrupted(prev)))
+ BUG();
* Test if we are atomic. Since do_exit() needs to call into
* schedule() atomically, we ignore that path. Otherwise whine

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/