mnt: Fix the error check in __detach_mounts
lookup_mountpoint can return either NULL or an error value.
Update the test in __detach_mounts to test for an error value
to avoid pathological cases causing a NULL pointer dereferences.
The callers of __detach_mounts should prevent it from ever being
called on an unlinked dentry but don't take any chances.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/namespace.c b/fs/namespace.c
index 1894d18..e8f7f8c 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1516,7 +1516,7 @@
namespace_lock();
mp = lookup_mountpoint(dentry);
- if (!mp)
+ if (IS_ERR_OR_NULL(mp))
goto out_unlock;
lock_mount_hash();