[PATCH 3.12 090/101] inetdevice: fixed signed integer overflow

From: Jiri Slaby
Date: Wed Dec 03 2014 - 06:31:49 EST

From: Vincent BENAYOUN <vincent.benayoun@xxxxxxxxxxxxxxxxx>

3.12-stable review patch. If anyone has any objections, please let me know.


[ Upstream commit 84bc88688e3f6ef843aa8803dbcd90168bb89faf ]

There could be a signed overflow in the following code.

The expression, (32-logmask) is comprised between 0 and 31 included.
It may be equal to 31.
In such a case the left shift will produce a signed integer overflow.
According to the C99 Standard, this is an undefined behavior.
A simple fix is to replace the signed int 1 with the unsigned int 1U.

Signed-off-by: Vincent BENAYOUN <vincent.benayoun@xxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
include/linux/inetdevice.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 79640e015a86..f738f922542d 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -234,7 +234,7 @@ static inline void in_dev_put(struct in_device *idev)
static __inline__ __be32 inet_make_mask(int logmask)
if (logmask)
- return htonl(~((1<<(32-logmask))-1));
+ return htonl(~((1U<<(32-logmask))-1));
return 0;


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