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, 3 deletions

diff --git a/drivers/isdn/mISDN/socket.c b/drivers/isdn/mISDN/socket.c
index 5cefb479c707..1be82284cf9d 100644
--- a/drivers/isdn/mISDN/socket.c
+++ b/drivers/isdn/mISDN/socket.c
@@ -135,7 +135,7 @@ mISDN_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
                 return err;
 
         if (msg->msg_name) {
-                struct sockaddr_mISDN *maddr = msg->msg_name;
+                DECLARE_SOCKADDR(struct sockaddr_mISDN *, maddr, msg->msg_name);
 
                 maddr->family = AF_ISDN;
                 maddr->dev = _pms(sk)->dev->id;
@@ -179,7 +179,6 @@ mISDN_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
         struct sock             *sk = sock->sk;
         struct sk_buff          *skb;
         int                     err = -ENOMEM;
-        struct sockaddr_mISDN   *maddr;
 
         if (*debug & DEBUG_SOCKET)
                 printk(KERN_DEBUG "%s: len %d flags %x ch %d proto %x\n",
@@ -214,7 +213,7 @@ mISDN_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
 
         if (msg->msg_namelen >= sizeof(struct sockaddr_mISDN)) {
                 /* if we have a address, we use it */
-                maddr = (struct sockaddr_mISDN *)msg->msg_name;
+                DECLARE_SOCKADDR(struct sockaddr_mISDN *, maddr, msg->msg_name);
                 mISDN_HEAD_ID(skb) = maddr->channel;
         } else { /* use default for L2 messages */
                 if ((sk->sk_protocol == ISDN_P_LAPD_TE) ||