[PATCH 1/2] ARM64: check stack pointer in get_wchan

[PATCH 1/2] ARM64: check stack pointer in get_wchan

[Konstantin Khlebnikov]

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>
---
 arch/arm64/kernel/process.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index de17c89..0adb8f0 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;

[PATCH 2/2] ARM64: fix framepointer check in unwind_frame

[Konstantin Khlebnikov]

We need at least 24 bytes above frame pointer.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
---
 arch/arm64/kernel/stacktrace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index d25459f..c3b6c63 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -43,7 +43,7 @@ int unwind_frame(struct stackframe *frame)
 	low  = frame->sp;
 	high = ALIGN(low, THREAD_SIZE);
 
-	if (fp < low || fp > high || fp & 0xf)
+	if (fp < low || fp > high - 0x18 || fp & 0xf)
 		return -EINVAL;
 
 	frame->sp = fp + 0x10;

[PATCH 1/2] ARM64: check stack pointer in get_wchan

[Catalin Marinas]

On Thu, Dec 05, 2013 at 01:30:10PM +0000, Konstantin Khlebnikov wrote:
> 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>

Thanks. Applied (both patches).

-- 
Catalin