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Subject[PATCH] unicore32: check stack pointer in get_wchan
Date
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.

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.

See commit 1b15ec7a7427 ("ARM: 7912/1: check stack pointer in get_wchan")
for details.

Signed-off-by: Young Xiao <92siuyang@gmail.com>
---
arch/unicore32/kernel/process.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/unicore32/kernel/process.c b/arch/unicore32/kernel/process.c
index 2bc10b8..1899ebc 100644
--- a/arch/unicore32/kernel/process.c
+++ b/arch/unicore32/kernel/process.c
@@ -277,6 +277,7 @@ 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;
@@ -285,9 +286,11 @@ 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;
--
2.7.4
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