From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=Dgga=T6=vger.kernel.org=linux-kernel-owner@kernel.org>
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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham
	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 8FCE4C28CC0
	for <linux-kernel@archiver.kernel.org>; Thu, 30 May 2019 19:33:08 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [209.132.180.67])
	by mail.kernel.org (Postfix) with ESMTP id 68D99260D2
	for <linux-kernel@archiver.kernel.org>; Thu, 30 May 2019 19:33:08 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1726531AbfE3TdH (ORCPT
        <rfc822;linux-kernel@archiver.kernel.org>);
        Thu, 30 May 2019 15:33:07 -0400
Received: from shards.monkeyblade.net ([23.128.96.9]:58880 "EHLO
        shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1725440AbfE3TdH (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 30 May 2019 15:33:07 -0400
Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::3d5])
        (using TLSv1 with cipher AES256-SHA (256/256 bits))
        (Client did not present a certificate)
        (Authenticated sender: davem-davemloft)
        by shards.monkeyblade.net (Postfix) with ESMTPSA id 7A9DC14DA817B;
        Thu, 30 May 2019 12:33:06 -0700 (PDT)
Date:   Thu, 30 May 2019 12:33:05 -0700 (PDT)
Message-Id: <20190530.123305.679690617064301115.davem@davemloft.net>
To:     92siuyang@gmail.com
Cc:     edumazet@google.com, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ipv4: tcp_input: fix stack out of bounds when parsing
 TCP options.
From:   David Miller <davem@davemloft.net>
In-Reply-To: <1559117459-27353-1-git-send-email-92siuyang@gmail.com>
References: <1559117459-27353-1-git-send-email-92siuyang@gmail.com>
X-Mailer: Mew version 6.8 on Emacs 26.1
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 30 May 2019 12:33:06 -0700 (PDT)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

From: Young Xiao <92siuyang@gmail.com>
Date: Wed, 29 May 2019 16:10:59 +0800

> The TCP option parsing routines in tcp_parse_options function could
> read one byte out of the buffer of the TCP options.
> 
> 1         while (length > 0) {
> 2                 int opcode = *ptr++;
> 3                 int opsize;
> 4
> 5                 switch (opcode) {
> 6                 case TCPOPT_EOL:
> 7                         return;
> 8                 case TCPOPT_NOP:        /* Ref: RFC 793 section 3.1 */
> 9                         length--;
> 10                        continue;
> 11                default:
> 12                        opsize = *ptr++; //out of bound access
> 
> If length = 1, then there is an access in line2.
> And another access is occurred in line 12.
> This would lead to out-of-bound access.
> 
> Therefore, in the patch we check that the available data length is
> larger enough to pase both TCP option code and size.
> 
> Signed-off-by: Young Xiao <92siuyang@gmail.com>

Applied.