net: compat_sys_recvmmsg user timespec arg can be NULL

We must test if user timespec is non-NULL before copying from userpace,
same as sys_recvmmsg().

Commiter note: changed it so that we have just one branch.

Signed-off-by: Jean-Mickael Guerin <jean-mickael.guerin@6wind.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 2 deletions

diff --git a/net/compat.c b/net/compat.c
index 6a2f75fb3f45..e1a56ade803b 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -758,9 +758,13 @@ asmlinkage long compat_sys_recvmmsg(int fd, struct compat_mmsghdr __user *mmsg,
 {
         int datagrams;
         struct timespec ktspec;
-        struct compat_timespec __user *utspec =
-                        (struct compat_timespec __user *)timeout;
+        struct compat_timespec __user *utspec;
 
+        if (timeout == NULL)
+                return __sys_recvmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
+                                      flags | MSG_CMSG_COMPAT, NULL);
+
+        utspec = (struct compat_timespec __user *)timeout;
         if (get_user(ktspec.tv_sec, &utspec->tv_sec) ||
             get_user(ktspec.tv_nsec, &utspec->tv_nsec))
                 return -EFAULT;