1 files changed, 14 insertions, 10 deletions

diff --git a/net/socket.c b/net/socket.c
index c226aceee65b..e83c416708af 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -221,12 +221,13 @@ static int move_addr_to_user(struct sockaddr_storage *kaddr, int klen,
         int err;
         int len;
 
+        BUG_ON(klen > sizeof(struct sockaddr_storage));
         err = get_user(len, ulen);
         if (err)
                 return err;
         if (len > klen)
                 len = klen;
-        if (len < 0 || len > sizeof(struct sockaddr_storage))
+        if (len < 0)
                 return -EINVAL;
         if (len) {
                 if (audit_sockaddr(klen, kaddr))
@@ -1840,8 +1841,10 @@ SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, ubuf, size_t, size,
         msg.msg_iov = &iov;
         iov.iov_len = size;
         iov.iov_base = ubuf;
-        msg.msg_name = (struct sockaddr *)&address;
-        msg.msg_namelen = sizeof(address);
+        /* Save some cycles and don't copy the address if not needed */
+        msg.msg_name = addr ? (struct sockaddr *)&address : NULL;
+        /* We assume all kernel code knows the size of sockaddr_storage */
+        msg.msg_namelen = 0;
         if (sock->file->f_flags & O_NONBLOCK)
                 flags |= MSG_DONTWAIT;
         err = sock_recvmsg(sock, &msg, size, flags);
@@ -1970,7 +1973,7 @@ static int copy_msghdr_from_user(struct msghdr *kmsg,
         if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
                 return -EFAULT;
         if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
-                return -EINVAL;
+                kmsg->msg_namelen = sizeof(struct sockaddr_storage);
         return 0;
 }
 
@@ -2221,16 +2224,14 @@ static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
                         goto out;
         }
 
-        /*
-         *      Save the user-mode address (verify_iovec will change the
-         *      kernel msghdr to use the kernel address space)
+        /* Save the user-mode address (verify_iovec will change the
+         * kernel msghdr to use the kernel address space)
          */
-
         uaddr = (__force void __user *)msg_sys->msg_name;
         uaddr_len = COMPAT_NAMELEN(msg);
-        if (MSG_CMSG_COMPAT & flags) {
+        if (MSG_CMSG_COMPAT & flags)
                 err = verify_compat_iovec(msg_sys, iov, &addr, VERIFY_WRITE);
-        } else
+        else
                 err = verify_iovec(msg_sys, iov, &addr, VERIFY_WRITE);
         if (err < 0)
                 goto out_freeiov;
@@ -2239,6 +2240,9 @@ static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
         cmsg_ptr = (unsigned long)msg_sys->msg_control;
         msg_sys->msg_flags = flags & (MSG_CMSG_CLOEXEC|MSG_CMSG_COMPAT);
 
+        /* We assume all kernel code knows the size of sockaddr_storage */
+        msg_sys->msg_namelen = 0;
+
         if (sock->file->f_flags & O_NONBLOCK)
                 flags |= MSG_DONTWAIT;
         err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys,