From e0d57714394f5e2ce4e2f9bbebf48e3c7a7fd3be Mon Sep 17 00:00:00 2001
From: Wang Long <long.wanglong@huawei.com>
Date: Thu, 5 Nov 2015 18:51:18 -0800
Subject: [PATCH] kasan: Fix a type conversion error

The current KASAN code can not find the following out-of-bounds bugs:

        char *ptr;
        ptr = kmalloc(8, GFP_KERNEL);
        memset(ptr+7, 0, 2);

the cause of the problem is the type conversion error in
*memory_is_poisoned_n* function.  So this patch fix that.

Signed-off-by: Wang Long <long.wanglong@huawei.com>
Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/kasan/kasan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 21c50dcbc9f0..2b21ccd55cd4 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -203,7 +203,7 @@ static __always_inline bool memory_is_poisoned_n(unsigned long addr,
 		s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
 
 		if (unlikely(ret != (unsigned long)last_shadow ||
-			((last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
+			((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
 			return true;
 	}
 	return false;
-- 
2.20.1