From: Pavel Shilovsky <pshilov@microsoft.com>
Date: Wed, 30 Nov 2016 00:14:43 +0000 (-0800)
Subject: CIFS: Fix a possible memory corruption in push locks
X-Git-Tag: v4.10-rc1~9^2~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e3d240e9d505fc67f8f8735836df97a794bbd946;p=thirdparty%2Flinux.git

CIFS: Fix a possible memory corruption in push locks

If maxBuf is not 0 but less than a size of SMB2 lock structure
we can end up with a memory corruption.

Cc: Stable <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
---

diff --git a/fs/cifs/smb2file.c b/fs/cifs/smb2file.c
index f9e766f464bee..b2aff0c6f22c5 100644
--- a/fs/cifs/smb2file.c
+++ b/fs/cifs/smb2file.c
@@ -260,7 +260,7 @@ smb2_push_mandatory_locks(struct cifsFileInfo *cfile)
 	 * and check it for zero before using.
 	 */
 	max_buf = tlink_tcon(cfile->tlink)->ses->server->maxBuf;
-	if (!max_buf) {
+	if (max_buf < sizeof(struct smb2_lock_element)) {
 		free_xid(xid);
 		return -EINVAL;
 	}