From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C1C25C2D0BF for ; Tue, 17 Dec 2019 00:56:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96B6324682 for ; Tue, 17 Dec 2019 00:56:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727264AbfLQA4I (ORCPT ); Mon, 16 Dec 2019 19:56:08 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35152 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726313AbfLQAvm (ORCPT ); Mon, 16 Dec 2019 19:51:42 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1ih15K-0003Mm-KW; Tue, 17 Dec 2019 00:51:34 +0000 Received: from ben by deadeye with local (Exim 4.93-RC7) (envelope-from ) id 1ih15I-0005Zc-Kd; Tue, 17 Dec 2019 00:51:32 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Aurelien Aptel" , "Ronnie Sahlberg" , "Roberto Bergantinos Corpas" , "Steve French" Date: Tue, 17 Dec 2019 00:46:56 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 082/136] CIFS: avoid using MID 0xFFFF In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 3.16.80-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Roberto Bergantinos Corpas commit 03d9a9fe3f3aec508e485dd3dcfa1e99933b4bdb upstream. According to MS-CIFS specification MID 0xFFFF should not be used by the CIFS client, but we actually do. Besides, this has proven to cause races leading to oops between SendReceive2/cifs_demultiplex_thread. On SMB1, MID is a 2 byte value easy to reach in CurrentMid which may conflict with an oplock break notification request coming from server Signed-off-by: Roberto Bergantinos Corpas Reviewed-by: Ronnie Sahlberg Reviewed-by: Aurelien Aptel Signed-off-by: Steve French Signed-off-by: Ben Hutchings --- fs/cifs/smb1ops.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/cifs/smb1ops.c +++ b/fs/cifs/smb1ops.c @@ -180,6 +180,9 @@ cifs_get_next_mid(struct TCP_Server_Info /* we do not want to loop forever */ last_mid = cur_mid; cur_mid++; + /* avoid 0xFFFF MID */ + if (cur_mid == 0xffff) + cur_mid++; /* * This nested loop looks more expensive than it is.