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/ipv4/udp.c b/net/ipv4/udp.c
index 3d3141fd0580..77bd16fa9f34 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -902,7 +902,7 @@ int udp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
          *      Get and verify the address.
          */
         if (msg->msg_name) {
-                struct sockaddr_in *usin = (struct sockaddr_in *)msg->msg_name;
+                DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name);
                 if (msg->msg_namelen < sizeof(*usin))
                         return -EINVAL;
                 if (usin->sin_family != AF_INET) {
@@ -1226,7 +1226,7 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                 size_t len, int noblock, int flags, int *addr_len)
 {
         struct inet_sock *inet = inet_sk(sk);
-        struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
         struct sk_buff *skb;
         unsigned int ulen, copied;
         int peeked, off = 0;