mount: handle NULL values in mnt_ns_release()

When calling in listmount() mnt_ns_release() may be passed a NULL
pointer. Handle that case gracefully.

Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/namespace.c b/fs/namespace.c
index 3860906..1ee17a0 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -180,7 +180,7 @@ static void mnt_ns_tree_add(struct mnt_namespace *ns)
 static void mnt_ns_release(struct mnt_namespace *ns)
 {
        /* keep alive for {list,stat}mount() */
-       if (refcount_dec_and_test(&ns->passive)) {
+       if (ns && refcount_dec_and_test(&ns->passive)) {
                fsnotify_mntns_delete(ns);
                put_user_ns(ns->user_ns);
                kfree(ns);