net: add build-time checks for msg->msg_name size

This is a follow-up patch to f3d3342602f8bc ("net: rework recvmsg
handler msg_name and msg_namelen logic").

DECLARE_SOCKADDR validates that the structure we use for writing the
name information to is not larger than the buffer which is reserved
for msg->msg_name (which is 128 bytes). Also use DECLARE_SOCKADDR
consistently in sendmsg code paths.

Signed-off-by: Steffen Hurrle <steffen@hurrle.net>
Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 800ca61758ff..29fc8bee9702 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1450,7 +1450,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
         struct sock *sk = sock->sk;
         struct net *net = sock_net(sk);
         struct unix_sock *u = unix_sk(sk);
-        struct sockaddr_un *sunaddr = msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
         struct sock *other = NULL;
         int namelen = 0; /* fake GCC */
         int err;
@@ -1912,7 +1912,7 @@ static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
         struct scm_cookie tmp_scm;
         struct sock *sk = sock->sk;
         struct unix_sock *u = unix_sk(sk);
-        struct sockaddr_un *sunaddr = msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
         int copied = 0;
         int check_creds = 0;
         int target;