[PATCH 3.2 078/147] cifs: check MaxPathNameComponentLength != 0 before using it

[Ben Hutchings]

3.2.95-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>

commit f74bc7c6679200a4a83156bb89cbf6c229fe8ec0 upstream.

And fix tcon leak in error path.

Signed-off-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx>
Signed-off-by: Steve French <smfrench@xxxxxxxxx>
Reviewed-by: David Disseldorp <ddiss@xxxxxxxxx>
[bwh: Backported to 3.2: cifs_tcon pointer is tcon, and there's no leak to fix]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -521,7 +521,8 @@ cifs_lookup(struct inode *parent_dir_ino
 	oplock = pTcon->ses->server->oplocks ? REQ_OPLOCK : 0;
 
 	/* Don't allow path components longer than the server max. */
-	if (unlikely(direntry->d_name.len >
+	if (unlikely(pTcon->fsAttrInfo.MaxPathNameComponentLength &&
+		     direntry->d_name.len >
 		     le32_to_cpu(pTcon->fsAttrInfo.MaxPathNameComponentLength))) {
 		rc = -ENAMETOOLONG;
 		goto lookup_out;