CIFS: Fix oops while mounting with prefixpath
commit fec11dd9a0109fe52fd631e5c510778d6cbff6cc caused
a regression when we have already mounted //server/share/a
and want to mount //server/share/a/b.
The problem is that lookup_one_len calls __lookup_hash
with nd pointer as NULL. Then __lookup_hash calls
do_revalidate in the case when dentry exists and we end
up with NULL pointer deference in cifs_d_revalidate:
if (nd->flags & LOOKUP_RCU)
return -ECHILD;
Fix this by checking nd for NULL.
Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: Shirish Pargaonkar <shirishp@us.ibm.com>
CC: Stable <stable@kernel.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 8e9d37d..c1bd030 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -636,7 +636,7 @@
static int
cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd)
{
- if (nd->flags & LOOKUP_RCU)
+ if (nd && (nd->flags & LOOKUP_RCU))
return -ECHILD;
if (direntry->d_inode) {
