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, 1 deletions

diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index dd4d506ef923..2954dcbca832 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -1808,6 +1808,7 @@ out:
                 rv = (flags & MSG_PEEK) ? -sk->sk_err : sock_error(sk);
 
         if ((rv >= 0) && msg->msg_name) {
+                __sockaddr_check_size(sizeof(struct sockaddr_dn));
                 memcpy(msg->msg_name, &scp->peer, sizeof(struct sockaddr_dn));
                 msg->msg_namelen = sizeof(struct sockaddr_dn);
         }
@@ -1914,7 +1915,7 @@ static int dn_sendmsg(struct kiocb *iocb, struct socket *sock,
         int err = 0;
         size_t sent = 0;
         int addr_len = msg->msg_namelen;
-        struct sockaddr_dn *addr = (struct sockaddr_dn *)msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_dn *, addr, msg->msg_name);
         struct sk_buff *skb = NULL;
         struct dn_skb_cb *cb;
         size_t len;