[v2.6.34-stable 026/213] iucv: Fix missing msg_namelen update in iucv_sock_recvmsg()

[Paul Gortmaker]

From: Mathias Krause <minipli@xxxxxxxxxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
    If you see a problem with using this for longterm, please comment.
                   -------------------

commit a5598bd9c087dc0efc250a5221e5d0e6f584ee88 upstream.

The current code does not fill the msg_name member in case it is set.
It also does not set the msg_namelen member to 0 and therefore makes
net/socket.c leak the local, uninitialized sockaddr_storage variable
to userland -- 128 bytes of kernel stack memory.

Fix that by simply setting msg_namelen to 0 as obviously nobody cared
about iucv_sock_recvmsg() not filling the msg_name in case it was set.

Cc: Ursula Braun <ursula.braun@xxxxxxxxxx>
Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 net/iucv/af_iucv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index c18286a2167b..1e3b2ec74622 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -1160,6 +1160,8 @@ static int iucv_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
 	struct sk_buff *skb, *rskb, *cskb;
 	int err = 0;
 
+	msg->msg_namelen = 0;
+
 	if ((sk->sk_state == IUCV_DISCONN || sk->sk_state == IUCV_SEVERED) &&
 	    skb_queue_empty(&iucv->backlog_skb_q) &&
 	    skb_queue_empty(&sk->sk_receive_queue) &&
-- 
1.8.5.2

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