From 0915921bde4eb5d943b17c175febac58a254d7b6 Mon Sep 17 00:00:00 2001
From: Shan Wei <shanwei@cn.fujitsu.com>
Date: Tue, 22 Sep 2009 15:41:10 +0000
Subject: ipv4: check optlen for IP_MULTICAST_IF option

Due to man page of setsockopt, if optlen is not valid, kernel should return
-EINVAL. But a simple testcase as following, errno is 0, which means setsockopt
is successful.
	addr.s_addr = inet_addr("192.1.2.3");
	setsockopt(s, IPPROTO_IP, IP_MULTICAST_IF, &addr, 1);
	printf("errno is %d\n", errno);

Xiaotian Feng(dfeng@redhat.com) caught the bug. We fix it firstly checking
the availability of optlen and then dealing with the logic like other options.

Reported-by: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Acked-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index fc7993e..5a06935 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -611,6 +611,9 @@ static int do_ip_setsockopt(struct sock *sk, int level,
 		 *	Check the arguments are allowable
 		 */
 
+		if (optlen < sizeof(struct in_addr))
+			goto e_inval;
+
 		err = -EFAULT;
 		if (optlen >= sizeof(struct ip_mreqn)) {
 			if (copy_from_user(&mreq, optval, sizeof(mreq)))
-- 
cgit v0.10.2