releases/3.10.23/net-clamp-msg_namelen-instead-of-returning-an-error.patch

From f1fe8bb11aa2772335c3e66da2bbdbaba36285ae Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Wed, 27 Nov 2013 15:40:21 +0300
Subject: net: clamp ->msg_namelen instead of returning an error

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit db31c55a6fb245fdbb752a2ca4aefec89afabb06 ]

If kmsg->msg_namelen > sizeof(struct sockaddr_storage) then in the
original code that would lead to memory corruption in the kernel if you
had audit configured.  If you didn't have audit configured it was
harmless.

There are some programs such as beta versions of Ruby which use too
large of a buffer and returning an error code breaks them.  We should
clamp the ->msg_namelen value instead.

Fixes: 1661bf364ae9 ("net: heap overflow in __audit_sockaddr()")
Reported-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Tested-by: Eric Wong <normalperson@yhbt.net>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/compat.c |    2 +-
 net/socket.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/compat.c
+++ b/net/compat.c
@@ -72,7 +72,7 @@ int get_compat_msghdr(struct msghdr *kms
 	    __get_user(kmsg->msg_flags, &umsg->msg_flags))
 		return -EFAULT;
 	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-		return -EINVAL;
+		kmsg->msg_namelen = sizeof(struct sockaddr_storage);
 	kmsg->msg_name = compat_ptr(tmp1);
 	kmsg->msg_iov = compat_ptr(tmp2);
 	kmsg->msg_control = compat_ptr(tmp3);
--- a/net/socket.c
+++ b/net/socket.c
@@ -1965,7 +1965,7 @@ static int copy_msghdr_from_user(struct
 	if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
 		return -EFAULT;
 	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-		return -EINVAL;
+		kmsg->msg_namelen = sizeof(struct sockaddr_storage);
 	return 0;
 }