autofs4: check for invalid dentry in getpath

Catch invalid dentry when calculating its path.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 1fe28e4754c2c7b44fc3516d4f633bc1c8d4351c..75e5955c3f6d4fe5cf30b3ffcc3d6bc21a9fbffb 100644 (file)
--- 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;
        }