cifs: fix CIFS_ENUMERATE_SNAPSHOTS oops

BugLink: http://bugs.launchpad.net/bugs/1692898
commit 6026685de33b0db5b2b6b0e9b41b3a1a3261033c upstream.

As with 618763958b22, an open directory may have a NULL private_data
pointer prior to readdir. CIFS_ENUMERATE_SNAPSHOTS must check for this
before dereference.

Fixes: 834170c85978 ("Enable previous version support")
Signed-off-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Steve French <smfrench@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c
index 001528781b6b0f80552c33f3d8e93fb9cfc27b86..b52b7ffa6d343114e9a5325a3f0edd215223561c 100644 (file)
--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -268,6 +268,8 @@ long cifs_ioctl(struct file *filep, unsigned int command, unsigned long arg)
                        rc = smb_mnt_get_fsinfo(xid, tcon, (void __user *)arg);
                        break;
                case CIFS_ENUMERATE_SNAPSHOTS:
+                       if (pSMBFile == NULL)
+                               break;
                        if (arg == 0) {
                                rc = -EINVAL;
                                goto cifs_ioc_exit;