tree 7322a985d8f37d229cdb6ef66ddae5bf218b9df6
parent ce07d891a0891d3c0d0c2d73d577490486b809e1
author Eric W. Biederman <ebiederm@xmission.com> 1421689725 -0600
committer Eric W. Biederman <ebiederm@xmission.com> 1428597596 -0500

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>