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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=unavailable 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 BDB9EC43219 for ; Wed, 1 May 2019 21:44:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 95CDF20866 for ; Wed, 1 May 2019 21:44:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726341AbfEAVoX (ORCPT ); Wed, 1 May 2019 17:44:23 -0400 Received: from www62.your-server.de ([213.133.104.62]:43006 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726196AbfEAVoW (ORCPT ); Wed, 1 May 2019 17:44:22 -0400 Received: from [78.46.172.2] (helo=sslproxy05.your-server.de) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1hLx1R-0008PH-NM; Wed, 01 May 2019 23:44:13 +0200 Received: from [173.228.226.134] (helo=localhost.localdomain) by sslproxy05.your-server.de with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1hLx1R-000OV8-8R; Wed, 01 May 2019 23:44:13 +0200 Subject: Re: [PATCH v2] bpf, x32: Fix bug for BPF_JMP | {BPF_JSGT, BPF_JSLE, BPF_JSLT, BPF_JSGE} To: Wang YanQing , ast@kernel.org, davem@davemloft.net, kuznet@ms2.inr.ac.ru, tglx@linutronix.de, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190427082826.GA16311@udknight> From: Daniel Borkmann Message-ID: Date: Wed, 1 May 2019 23:44:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20190427082826.GA16311@udknight> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.100.3/25436/Wed May 1 09:58:19 2019) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 04/27/2019 10:28 AM, Wang YanQing wrote: > The current method to compare 64-bit numbers for conditional jump is: > > 1) Compare the high 32-bit first. > > 2) If the high 32-bit isn't the same, then goto step 4. > > 3) Compare the low 32-bit. > > 4) Check the desired condition. > > This method is right for unsigned comparison, but it is buggy for signed > comparison, because it does signed comparison for low 32-bit too. > > There is only one sign bit in 64-bit number, that is the MSB in the 64-bit > number, it is wrong to treat low 32-bit as signed number and do the signed > comparison for it. > > This patch fixes the bug and adds a testcase in selftests/bpf for such bug. > > Signed-off-by: Wang YanQing Applied, thanks!