Patch "sched: panic on corrupted stack end" has been added to the 4.6-stable tree

Patch "sched: panic on corrupted stack end" has been added to the 4.6-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    sched: panic on corrupted stack end

to the 4.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     sched-panic-on-corrupted-stack-end.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 29d6455178a09e1dc340380c582b13356227e8df Mon Sep 17 00:00:00 2001
From: Jann Horn <jannh@google.com>
Date: Wed, 1 Jun 2016 11:55:07 +0200
Subject: sched: panic on corrupted stack end

From: Jann Horn <jannh@google.com>

commit 29d6455178a09e1dc340380c582b13356227e8df upstream.

Until now, hitting this BUG_ON caused a recursive oops (because oops
handling involves do_exit(), which calls into the scheduler, which in
turn raises an oops), which caused stuff below the stack to be
overwritten until a panic happened (e.g.  via an oops in interrupt
context, caused by the overwritten CPU index in the thread_info).

Just panic directly.

Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/sched/core.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3047,7 +3047,8 @@ static noinline void __schedule_bug(stru
 static inline void schedule_debug(struct task_struct *prev)
 {
 #ifdef CONFIG_SCHED_STACK_END_CHECK
-	BUG_ON(task_stack_end_corrupted(prev));
+	if (task_stack_end_corrupted(prev))
+		panic("corrupted stack end detected inside scheduler\n");
 #endif
 
 	if (unlikely(in_atomic_preempt_off())) {


Patches currently in stable-queue which might be from jannh@google.com are

queue-4.6/ecryptfs-forbid-opening-files-without-mmap-handler.patch
queue-4.6/sched-panic-on-corrupted-stack-end.patch
queue-4.6/proc-prevent-stacking-filesystems-on-top.patch