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authorKonstantin Khlebnikov <k.khlebnikov@samsung.com>2013-12-05 14:21:36 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2013-12-10 00:24:31 +0100
commit1b15ec7a7427d4188ba91b9bbac696250a059d22 (patch)
tree1f5db8d672dbfb84078ef6814f2bc3aed2937a02 /arch
parentARM: 7909/1: mm: Call setup_dma_zone() post early_paging_init() (diff)
downloadlinux-1b15ec7a7427d4188ba91b9bbac696250a059d22.tar.xz
linux-1b15ec7a7427d4188ba91b9bbac696250a059d22.zip
ARM: 7912/1: check stack pointer in get_wchan
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 Cc: <stable@vger.kernel.org> Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/kernel/process.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 94f6b05f9e24..92f7b15dd221 100644
--- 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_struct *p)
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;