Subject: [PATCH 2/2] ARM: fix framepointer check in unwind_frame

From: [email-masked] (Konstantin Khlebnikov)
Date: Thu, 05 Dec 2013 12:34:30 +0400

This patch fixes corner case when (fp + 4) overflows unsigned long,
for example: fp = 0xFFFFFFFF -> fp + 4 == 3.

Signed-off-by: Konstantin Khlebnikov <[email-masked]>
---
 arch/arm/kernel/stacktrace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index 00f79e5..af4e8c8 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -31,7 +31,7 @@ int notrace unwind_frame(struct stackframe *frame)
 	high = ALIGN(low, THREAD_SIZE);
 
 	/* check current frame pointer is within bounds */
-	if (fp < (low + 12) || fp + 4 >= high)
+	if (fp < low + 12 || fp > high - 4)
 		return -EINVAL;
 
 	/* restore the registers from the stack frame */