llc: Fix missing msg_namelen update in llc_ui_recvmsg()

[ Upstream commit c77a4b9cffb6215a15196ec499490d116dfad181 ]

For stream sockets the code misses to update 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. The msg_namelen update is also missing for datagram sockets
in case the socket is shutting down during receive.

Fix both issues by setting msg_namelen to 0 early. It will be
updated later if we're going to fill the msg_name member.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 99a60d545b2488840afe25255366f48c45a9ba44..e5565c71cbbb5d9889c3f644ae1d00f8d1708287 100644 (file)
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -720,6 +720,8 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock,
        int target;     /* Read at least this many bytes */
        long timeo;
 
+       msg->msg_namelen = 0;
+
        lock_sock(sk);
        copied = -ENOTCONN;
        if (unlikely(sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_LISTEN))