From c076cbf218f3cb83dffe6982587d2b9751318962 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Mon, 19 Jan 2015 11:48:45 -0600
Subject: mnt: Fix the error check in __detach_mounts

commit f53e57975151f54ad8caa1b0ac8a78091cd5700a upstream.

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.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/namespace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'fs')

diff --git a/fs/namespace.c b/fs/namespace.c
index 24de1e9b1d49..9e338951c4d0 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1518,7 +1518,7 @@ void __detach_mounts(struct dentry *dentry)
 
 	namespace_lock();
 	mp = lookup_mountpoint(dentry);
-	if (!mp)
+	if (IS_ERR_OR_NULL(mp))
 		goto out_unlock;
 
 	lock_mount_hash();
-- 
cgit v1.2.3