[PATCH 01/10] autofs4 - check for invalid dentry in getpath

[Ian Kent <raven@themaw.net>]

Catch invalid dentry when calculating its path.

When autofs4_getpath() is called without the BKL (as it is when called
via ->unlocked_ioctl) it is possible to encounter a dentry that is in
the process of being freed which has a zero length name.

---

 fs/autofs4/waitq.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)


diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 1fe28e4..75e5955 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -171,7 +171,7 @@ static int autofs4_getpath(struct autofs_sb_info *sbi,
 	for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
 		len += tmp->d_name.len + 1;
 
-	if (--len > NAME_MAX) {
+	if (!len || --len > NAME_MAX) {
 		spin_unlock(&dcache_lock);
 		return 0;
 	}