cifs: Do not lookup hashed negative dentry in cifs_atomic_open
We do not need to lookup a hashed negative directory since we have
already revalidated it before and have found it to be fine.
This also prevents a crash in cifs_lookup() when it attempts to rehash
the already hashed negative lookup dentry.
The patch has been tested using the reproducer at
https://bugzilla.redhat.com/show_bug.cgi?id=867344#c28
Cc: <stable@kernel.org> # 3.6.x
Reported-by: Vit Zahradka <vit.zahradka@tiscali.cz>
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 7c0a812..d3671f2 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -398,7 +398,16 @@
* in network traffic in the other paths.
*/
if (!(oflags & O_CREAT)) {
- struct dentry *res = cifs_lookup(inode, direntry, 0);
+ struct dentry *res;
+
+ /*
+ * Check for hashed negative dentry. We have already revalidated
+ * the dentry and it is fine. No need to perform another lookup.
+ */
+ if (!d_unhashed(direntry))
+ return -ENOENT;
+
+ res = cifs_lookup(inode, direntry, 0);
if (IS_ERR(res))
return PTR_ERR(res);
