Code: static int caif_seqpkt_recvmsg(struct kiocb *iocb, struct socket *sock,
				struct msghdr *m, size_t len, int flags)

{
	struct sock *sk = sock->sk;
	struct sk_buff *skb;
	int ret;
	int copylen;

	ret = -EOPNOTSUPP;
 	if (m->msg_flags&MSG_OOB)
 		goto read_error;
 
 	skb = skb_recv_datagram(sk, flags, 0 , &ret);
 	if (!skb)
 		goto read_error;
	copylen = skb->len;
	if (len < copylen) {
		m->msg_flags |= MSG_TRUNC;
		copylen = len;
	}

	ret = skb_copy_datagram_iovec(skb, 0, m->msg_iov, copylen);
	if (ret)
		goto out_free;

	ret = (flags & MSG_TRUNC) ? skb->len : copylen;
out_free:
	skb_free_datagram(sk, skb);
	caif_check_flow_release(sk);
	return ret;

read_error:
	return ret;
}

Vulnerability Type: +Info 
CWE ID: CWE-200
Summary: The caif_seqpkt_recvmsg function in net/caif/caif_socket.c in the Linux kernel before 3.9-rc7 does not initialize a certain length variable, which allows local users to obtain sensitive information from kernel stack memory via a crafted recvmsg or recvfrom system call.
Commit Message: caif: Fix missing msg_namelen update in caif_seqpkt_recvmsg()

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 caif_seqpkt_recvmsg() not filling the msg_name in case it was
set.

Cc: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>