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/ax25/af_ax25.c b/net/ax25/af_ax25.c
index 7bb1605bdfd9..c35c3f48fc0f 100644
--- a/net/ax25/af_ax25.c
+++ b/net/ax25/af_ax25.c
@@ -1435,7 +1435,7 @@ out:
 static int ax25_sendmsg(struct kiocb *iocb, struct socket *sock,
                         struct msghdr *msg, size_t len)
 {
-        struct sockaddr_ax25 *usax = (struct sockaddr_ax25 *)msg->msg_name;
+        DECLARE_SOCKADDR(struct sockaddr_ax25 *, usax, msg->msg_name);
         struct sock *sk = sock->sk;
         struct sockaddr_ax25 sax;
         struct sk_buff *skb;
@@ -1640,7 +1640,7 @@ static int ax25_recvmsg(struct kiocb *iocb, struct socket *sock,
                 ax25_digi digi;
                 ax25_address src;
                 const unsigned char *mac = skb_mac_header(skb);
-                struct sockaddr_ax25 *sax = msg->msg_name;
+                DECLARE_SOCKADDR(struct sockaddr_ax25 *, sax, msg->msg_name);
 
                 memset(sax, 0, sizeof(struct full_sockaddr_ax25));
                 ax25_addr_parse(mac + 1, skb->data - mac - 1, &src, NULL,