Commit 3ca30d40 authored by Pavel Shilovsky's avatar Pavel Shilovsky Committed by Al Viro

CIFS: Fix oops while mounting with prefixpath

commit fec11dd9 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: default avatarPavel Shilovsky <piastryyy@gmail.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 340a0a01
...@@ -641,7 +641,7 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry, ...@@ -641,7 +641,7 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
static int static int
cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd) cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd)
{ {
if (nd->flags & LOOKUP_RCU) if (nd && (nd->flags & LOOKUP_RCU))
return -ECHILD; return -ECHILD;
if (direntry->d_inode) { if (direntry->d_inode) {
......
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