ARM64: 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.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index de17c89985db..0adb8f0f4549 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -308,6 +308,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
 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;
@@ -315,9 +316,11 @@ unsigned long get_wchan(struct task_struct *p)
         frame.fp = thread_saved_fp(p);
         frame.sp = thread_saved_sp(p);
         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))
                         return 0;
                 if (!in_sched_functions(frame.pc))
                         return frame.pc;