[ 3.5.y.z extended stable ] Patch "ipv4: avoid undefined behavior in do_ip_setsockopt()" has been added to staging queue

[Herton Ronaldo Krzesinski]

This is a note to let you know that I have just added a patch titled

    ipv4: avoid undefined behavior in do_ip_setsockopt()

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

>From 9414871116b6b4aae319a88b0fe18af48f1a2097 Mon Sep 17 00:00:00 2001
From: Xi Wang <xi.wang at gmail.com>
Date: Sun, 11 Nov 2012 11:20:01 +0000
Subject: [PATCH] ipv4: avoid undefined behavior in do_ip_setsockopt()

commit 0c9f79be295c99ac7e4b569ca493d75fdcc19e4e upstream.

(1<<optname) is undefined behavior in C with a negative optname or
optname larger than 31.  In those cases the result of the shift is
not necessarily zero (e.g., on x86).

This patch simplifies the code with a switch statement on optname.
It also allows the compiler to generate better code (e.g., using a
64-bit mask).

Signed-off-by: Xi Wang <xi.wang at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 net/ipv4/ip_sockglue.c |   35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 0d11f23..8285f00 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -456,19 +456,28 @@ static int do_ip_setsockopt(struct sock *sk, int level,
 	struct inet_sock *inet = inet_sk(sk);
 	int val = 0, err;

-	if (((1<<optname) & ((1<<IP_PKTINFO) | (1<<IP_RECVTTL) |
-			     (1<<IP_RECVOPTS) | (1<<IP_RECVTOS) |
-			     (1<<IP_RETOPTS) | (1<<IP_TOS) |
-			     (1<<IP_TTL) | (1<<IP_HDRINCL) |
-			     (1<<IP_MTU_DISCOVER) | (1<<IP_RECVERR) |
-			     (1<<IP_ROUTER_ALERT) | (1<<IP_FREEBIND) |
-			     (1<<IP_PASSSEC) | (1<<IP_TRANSPARENT) |
-			     (1<<IP_MINTTL) | (1<<IP_NODEFRAG))) ||
-	    optname == IP_UNICAST_IF ||
-	    optname == IP_MULTICAST_TTL ||
-	    optname == IP_MULTICAST_ALL ||
-	    optname == IP_MULTICAST_LOOP ||
-	    optname == IP_RECVORIGDSTADDR) {
+	switch (optname) {
+	case IP_PKTINFO:
+	case IP_RECVTTL:
+	case IP_RECVOPTS:
+	case IP_RECVTOS:
+	case IP_RETOPTS:
+	case IP_TOS:
+	case IP_TTL:
+	case IP_HDRINCL:
+	case IP_MTU_DISCOVER:
+	case IP_RECVERR:
+	case IP_ROUTER_ALERT:
+	case IP_FREEBIND:
+	case IP_PASSSEC:
+	case IP_TRANSPARENT:
+	case IP_MINTTL:
+	case IP_NODEFRAG:
+	case IP_UNICAST_IF:
+	case IP_MULTICAST_TTL:
+	case IP_MULTICAST_ALL:
+	case IP_MULTICAST_LOOP:
+	case IP_RECVORIGDSTADDR:
 		if (optlen >= sizeof(int)) {
 			if (get_user(val, (int __user *) optval))
 				return -EFAULT;
--
1.7.9.5