From: David Disseldorp <ddiss@suse.de>
Date: Wed, 3 May 2017 15:39:08 +0000 (+0200)
Subject: cifs: fix CIFS_ENUMERATE_SNAPSHOTS oops
X-Git-Tag: v4.10.17~27
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cd01b999953bc9f7239429eb6dcabe1ae1f50e45;p=thirdparty%2Fkernel%2Fstable.git

cifs: fix CIFS_ENUMERATE_SNAPSHOTS oops

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>
---

diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c
index 001528781b6b0..b52b7ffa6d343 100644
--- 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;