[NET]: Do not leak MSG_CMSG_COMPAT into userspace.

Noticed by Sridhar Samudrala.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/socket.c b/net/socket.c
index c699e93c33d7..f9264472377f 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1862,7 +1862,8 @@ asmlinkage long sys_recvmsg(int fd, struct msghdr __user *msg, unsigned int flag
                 if (err < 0)
                         goto out_freeiov;
         }
-        err = __put_user(msg_sys.msg_flags, COMPAT_FLAGS(msg));
+        err = __put_user((msg_sys.msg_flags & ~MSG_CMSG_COMPAT),
+                         COMPAT_FLAGS(msg));
         if (err)
                 goto out_freeiov;
         if (MSG_CMSG_COMPAT & flags)