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authorKonstantin Khlebnikov <k.khlebnikov@samsung.com>2013-12-05 14:21:36 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-20 07:45:07 -0800
commit7768a84a3e65465c0fc96ec3d447453ea79dbaed (patch)
tree314d94c539e050b3b621feed547f8778ab1b131a /arch
parent58a6ea8d32e9d23c8cc531a800aabc2c8f2f95aa (diff)
ARM: 7912/1: check stack pointer in get_wchan
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@samsung.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 ab1fe3bb31f..ac4c2e5e17e 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -408,6 +408,7 @@ 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;
@@ -416,9 +417,11 @@ 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;