[PATCH v3 3/3] sched: BUG when stack end location is over written
From: Aaron Tomlin <hidden>
Date: 2014-09-11 15:44:13
Also in:
lkml
Subsystem:
library code, scheduler, the rest · Maintainers:
Andrew Morton, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
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: Aaron Tomlin <redacted> --- kernel/sched/core.c | 3 +++ lib/Kconfig.debug | 12 ++++++++++++ 2 files changed, 15 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ec1a286..0b70b73 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) { +#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
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index a285900..2a8280a 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug@@ -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 y + 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
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1.9.3