From: Aaron Tomlin <atomlin@redhat•com>
To: peterz@infradead•org
Cc: dzickus@redhat•com, jcastillo@redhat•com, riel@redhat•com,
x86@kernel•org, akpm@linux-foundation•org, minchan@kernel•org,
bmr@redhat•com, prarit@redhat•com, oleg@redhat•com,
rostedt@goodmis•org, linux-kernel@vger•kernel.org,
hannes@cmpxchg•org, mingo@redhat•com,
aneesh.kumar@linux•vnet.ibm.com, atomlin@redhat•com,
jgh@redhat•com, linuxppc-dev@lists•ozlabs.org,
tglx@linutronix•de, akpm@google•com
Subject: [PATCH v4 3/3] sched: BUG when stack end location is over written
Date: Fri, 12 Sep 2014 14:16:19 +0100 [thread overview]
Message-ID: <1410527779-8133-4-git-send-email-atomlin@redhat.com> (raw)
In-Reply-To: <1410527779-8133-1-git-send-email-atomlin@redhat.com>
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 <atomlin@redhat•com>
---
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..6ed1a24 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..e58163d 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 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
--
1.9.3
prev parent reply other threads:[~2014-09-12 13:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-12 13:16 [PATCH v4 0/3] sched: Always check the integrity of the canary Aaron Tomlin
2014-09-12 13:16 ` [PATCH v4 1/3] init/main.c: Give init_task a canary Aaron Tomlin
2014-09-18 20:27 ` Oleg Nesterov
2014-09-12 13:16 ` [PATCH v4 2/3] sched: Add helper for task stack page overrun checking Aaron Tomlin
2014-09-12 13:16 ` Aaron Tomlin [this message]
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