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: v3.12.70~194
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dd4617bd371f4b916553f7b0c6c37f3ed0562b9f;p=thirdparty%2Fkernel%2Fstable.git

CIFS: Fix a possible memory corruption in push locks

commit e3d240e9d505fc67f8f8735836df97a794bbd946 upstream.

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

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---

diff --git a/fs/cifs/smb2file.c b/fs/cifs/smb2file.c
index 45992944e2385..b87b075049474 100644
--- a/fs/cifs/smb2file.c
+++ b/fs/cifs/smb2file.c
@@ -241,7 +241,7 @@ 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;
 	}