[3.11.y.z extended stable] Patch "net: add BUG_ON if kernel advertises msg_namelen > sizeof(struct" has been added to staging queue

[Luis Henriques]

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

    net: add BUG_ON if kernel advertises msg_namelen > sizeof(struct

to the linux-3.11.y-queue branch of the 3.11.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-3.11.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 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 8acd829a34da4fee5b3b8bdf2798fe3aa83561d2 Mon Sep 17 00:00:00 2001
From: Hannes Frederic Sowa <hannes at stressinduktion.org>
Date: Thu, 21 Nov 2013 03:14:34 +0100
Subject: net: add BUG_ON if kernel advertises msg_namelen > sizeof(struct
 sockaddr_storage)

commit 68c6beb373955da0886d8f4f5995b3922ceda4be upstream.

In that case it is probable that kernel code overwrote part of the
stack. So we should bail out loudly here.

The BUG_ON may be removed in future if we are sure all protocols are
conformant.

Suggested-by: Eric Dumazet <eric.dumazet at gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes at stressinduktion.org>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/socket.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/socket.c b/net/socket.c
index 5158ff7..65b0013 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -221,12 +221,13 @@ static int move_addr_to_user(struct sockaddr_storage *kaddr, int klen,
 	int err;
 	int len;

+	BUG_ON(klen > sizeof(struct sockaddr_storage));
 	err = get_user(len, ulen);
 	if (err)
 		return err;
 	if (len > klen)
 		len = klen;
-	if (len < 0 || len > sizeof(struct sockaddr_storage))
+	if (len < 0)
 		return -EINVAL;
 	if (len) {
 		if (audit_sockaddr(klen, kaddr))
--
1.8.3.2