mnt: If fs_fully_visible fails call put_filesystem.

Add this trivial missing error handling.

Cc: stable@vger.kernel.org
Fixes: 1b852bceb0d1 ("mnt: Refactor the logic for mounting sysfs and proc in a user namespace")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 4fb1691b4355..9d45c8a3414f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2409,8 +2409,10 @@ static int do_new_mount(struct path *path, const char *fstype, int flags,
                         mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV;
                 }
                 if (type->fs_flags & FS_USERNS_VISIBLE) {
-                        if (!fs_fully_visible(type, &mnt_flags))
+                        if (!fs_fully_visible(type, &mnt_flags)) {
+                                put_filesystem(type);
                                 return -EPERM;
+                        }
                 }
         }