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, 3 insertions, 4 deletions

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index cae5262a337c..e09e8839d622 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -700,7 +700,7 @@ static int ping_v4_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *m
          */
 
         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)
@@ -873,7 +873,7 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
         /* Copy the address and add cmsg data. */
         if (family == AF_INET) {
-                struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
+                DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
 
                 if (sin) {
                         sin->sin_family = AF_INET;
@@ -890,8 +890,7 @@ int ping_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
         } else if (family == AF_INET6) {
                 struct ipv6_pinfo *np = inet6_sk(sk);
                 struct ipv6hdr *ip6 = ipv6_hdr(skb);
-                struct sockaddr_in6 *sin6 =
-                        (struct sockaddr_in6 *)msg->msg_name;
+                DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
 
                 if (sin6) {
                         sin6->sin6_family = AF_INET6;