This is a note to let you know that I've just added the patch titled
ARM: 7912/1: check stack pointer in get_wchan
to the 3.12-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:
arm-7912-1-check-stack-pointer-in-get_wchan.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1b15ec7a7427d4188ba91b9bbac696250a059d22 Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
Date: Thu, 5 Dec 2013 14:21:36 +0100
Subject: ARM: 7912/1: check stack pointer in get_wchan
From: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
commit 1b15ec7a7427d4188ba91b9bbac696250a059d22 upstream.
get_wchan() is lockless. Task may wakeup at any time and change its own stack,
thus each next stack frame may be overwritten and filled with random stuff.
/proc/$pid/stack interface had been disabled for non-current tasks, see [1]
But 'wchan' still allows to trigger stack frame unwinding on volatile stack.
This patch fixes oops in unwind_frame() by adding stack pointer validation on
each step (as x86 code do), unwind_frame() already checks frame pointer.
Also I've found another report of this oops on stackoverflow (irony).
Link: http://www.spinics.net/lists/arm-kernel/msg110589.html [1]
Link: http://stackoverflow.com/questions/18479894/unwind-frame-cause-a-kernel-paging-error
Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
Acked-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kernel/process.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -404,6 +404,7 @@ EXPORT_SYMBOL(dump_fpu);
unsigned long get_wchan(struct task_struct *p)
{
struct stackframe frame;
+ unsigned long stack_page;
int count = 0;
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
@@ -412,9 +413,11 @@ unsigned long get_wchan(struct task_stru
frame.sp = thread_saved_sp(p);
frame.lr = 0; /* recovered from the stack */
frame.pc = thread_saved_pc(p);
+ stack_page = (unsigned long)task_stack_page(p);
do {
- int ret = unwind_frame(&frame);
- if (ret < 0)
+ if (frame.sp < stack_page ||
+ frame.sp >= stack_page + THREAD_SIZE ||
+ unwind_frame(&frame) < 0)
return 0;
if (!in_sched_functions(frame.pc))
return frame.pc;
Patches currently in stable-queue which might be from k.khlebnikov@xxxxxxxxxxx are
queue-3.12/arm-7913-1-fix-framepointer-check-in-unwind_frame.patch
queue-3.12/arm-7912-1-check-stack-pointer-in-get_wchan.patch
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