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>

2 files changed, 2 insertions, 3 deletions

diff --git a/net/rds/recv.c b/net/rds/recv.c
index de339b24ca14..bd82522534fc 100644
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -402,7 +402,7 @@ int rds_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
         struct rds_sock *rs = rds_sk_to_rs(sk);
         long timeo;
         int ret = 0, nonblock = msg_flags & MSG_DONTWAIT;
-        struct sockaddr_in *sin;
+        DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
         struct rds_incoming *inc = NULL;
 
         /* udp_recvmsg()->sock_recvtimeo() gets away without locking too.. */
@@ -479,7 +479,6 @@ int rds_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
 
                 rds_stats_inc(s_recv_delivered);
 
-                sin = (struct sockaddr_in *)msg->msg_name;
                 if (sin) {
                         sin->sin_family = AF_INET;
                         sin->sin_port = inc->i_hdr.h_sport;
diff --git a/net/rds/send.c b/net/rds/send.c
index 88eace57dd6b..a82fb660ec00 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -922,7 +922,7 @@ int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg,
 {
         struct sock *sk = sock->sk;
         struct rds_sock *rs = rds_sk_to_rs(sk);
-        struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
         __be32 daddr;
         __be16 dport;
         struct rds_message *rm = NULL;