do_mount(): fix a leak introduced in 3.9 ("mount: consolidate permission checks")

Cc: stable@vger.kernel.org
Bisected-by: NMichael Leun <lkml20130126@newton.leun.net>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs/namespace.c

@@ -2284,12 +2284,11 @@ long do_mount(const char *dev_name, const char *dir_name,
 
 	retval = security_sb_mount(dev_name, &path,
 				   type_page, flags, data_page);
+	if (!retval && !may_mount())
+		retval = -EPERM;
 	if (retval)
 		goto dput_out;
 
-	if (!may_mount())
-		return -EPERM;
-
 	/* Default to relatime unless overriden */
 	if (!(flags & MS_NOATIME))
 		mnt_flags |= MNT_RELATIME;