[patch] skip posix open if nameidata is null

While creating a file on a server which supports unix extensions
such as Samba, if a file is being created which does not supply
nameidata (i.e. nd is null), cifs client can oops when calling
cifs_posix_open.

The simplest solution is, do not open a file using posix semantics
if nameidata parameter is NULL even if server supports posix semantics.

I do not see a way to reach vfsmount (structure) field if nameidata
is not supplied to call posix open (cifs_posix_open).


Signed-off-by: Shirish Pargaonkar <[email protected]>
Reported-by: Eugene Teo <[email protected]>
---

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index e9f7ecc..eef8d83 100644
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -317,7 +317,7 @@ cifs_create(struct inode *inode, struct dentry *direntry, int mode,
 	else
 		oflags = FMODE_READ;
 
-	if (tcon->unix_ext && (tcon->ses->capabilities & CAP_UNIX) &&
+	if (nd && tcon->unix_ext && (tcon->ses->capabilities & CAP_UNIX) &&
 	    (CIFS_UNIX_POSIX_PATH_OPS_CAP &
 			le64_to_cpu(tcon->fsUnixInfo.Capability))) {
 		rc = cifs_posix_open(full_path, &newinode, nd->path.mnt,