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=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 6AB8FC43381 for ; Sat, 2 Mar 2019 10:12:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22D6C20838 for ; Sat, 2 Mar 2019 10:12:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cogentembedded-com.20150623.gappssmtp.com header.i=@cogentembedded-com.20150623.gappssmtp.com header.b="eQQ9zfpN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726114AbfCBKMN (ORCPT ); Sat, 2 Mar 2019 05:12:13 -0500 Received: from mail-lf1-f66.google.com ([209.85.167.66]:40711 "EHLO mail-lf1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726049AbfCBKMN (ORCPT ); Sat, 2 Mar 2019 05:12:13 -0500 Received: by mail-lf1-f66.google.com with SMTP id a8so232077lfi.7 for ; Sat, 02 Mar 2019 02:12:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cogentembedded-com.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=cYRHzHIJ93lUPFjUOboVeHRSEAE23+rZlrsUkMjtfhc=; b=eQQ9zfpNAdp930A05+Mu/kBPGS9qD57Jzpj9tUFTjuCrFNqmqZibaq1IE/KR8Ca2Lo 6N17Oyuc+QG6o51lipGS2EWSoi8FLujKTnU4x3kxV097rwOIR4tCZqSmI7Bx16+uvUpY gl4P7kBZGDeZpjQfWbXGYqqC7QLZa4+DC0lEf96aaes/jjIuq9NavK0WAWn76/4a5eWP igHVx7G6M8/fQFB0OLUi/rwpnpYELr5SL8tMMV6T6eCTuz41pFdJo8/P0+u8GnvTzkxt 6rK3w7CHbZHKMdQAXxvtoFv+n49lBvR6WGPag3YprBAeboCwHgsZrujvZ72L9ZbMl+B1 c2/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=cYRHzHIJ93lUPFjUOboVeHRSEAE23+rZlrsUkMjtfhc=; b=GxcrPczOFfNhVfJ4LuUtFdzMMSyiA24SKghxcBQXQQEwj8k6t16Y3ZSjb+H0ABvOah +RunoatI3lYXGDhORTcHwu8gWYVZ/Q6nobwKFxADrZnKPlpkTChLmHHyQI5rHh2gaRtg z0rUMvMkD3FvkIWy3MepnHOl/mHtL1+aJME7y/ZSiQhoB+sOMmCfpzF8rZ337FbjqVGp xTsaA7es4Jb+6dHA8LQuoQMPHAgllHNGxP2OLJOpdcC3LmDACXFRIOz7aaHwvsMRd63Y uF4SrNoumRPrrzFcLnav700EQyQbVfbiesbUcMG4gqWuWL27KwUtG9qvkKOvzsKmMR2z wnFw== X-Gm-Message-State: APjAAAUzU74sMv3Cydee9QUoevraw4tL6hExrVQ+OgPEH/OG2HsmhvLC YKMOTxV5BUeZ0JlcG33DBPPD9g== X-Google-Smtp-Source: APXvYqwbOuV01juLEEk/bhBYY+UJMI2Pl/Evf/+hmN3EtfzzA2DcGDw7P1pAgQrJpB0YDv35eFP9IQ== X-Received: by 2002:a19:2d44:: with SMTP id t4mr5241924lft.90.1551521531319; Sat, 02 Mar 2019 02:12:11 -0800 (PST) Received: from [192.168.0.199] ([31.173.84.84]) by smtp.gmail.com with ESMTPSA id t135sm109119lff.74.2019.03.02.02.12.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 02 Mar 2019 02:12:10 -0800 (PST) Subject: Re: [PATCH bpf] bpf: fix sanitation rewrite in case of non-pointers To: Daniel Borkmann , ast@fb.com Cc: afabre@cloudflare.com, marek@cloudflare.com, bpf@vger.kernel.org, netdev@vger.kernel.org References: <20190301210529.8218-1-daniel@iogearbox.net> From: Sergei Shtylyov Message-ID: <96367b1a-4ab5-8f1d-1823-a65ba48fa3cc@cogentembedded.com> Date: Sat, 2 Mar 2019 13:11:57 +0300 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <20190301210529.8218-1-daniel@iogearbox.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Hello! On 02.03.2019 0:05, Daniel Borkmann wrote: > Marek reported that he saw an issue with the below snippet in that > timing measurements where off when loaded as unpriv while results Were? > were reasonable when loaded as privileged: > > [...] > uint64_t a = bpf_ktime_get_ns(); > uint64_t b = bpf_ktime_get_ns(); > uint64_t delta = b - a; > if ((int64_t)delta > 0) { > [...] > > Turns out there is a bug where a corner case is missing in the fix > d3bd7413e0ca ("bpf: fix sanitation of alu op with pointer / scalar > type from different paths"), namely fixup_bpf_calls() only checks > whether aux has a non-zero alu_state, but it also needs to test for > the case of BPF_ALU_NON_POINTER since in both occasions we need to > skip the masking rewrite (as there is nothing to mask). > > Fixes: d3bd7413e0ca ("bpf: fix sanitation of alu op with pointer / scalar type from different paths") > Reported-by: Marek Majkowski > Reported-by: Arthur Fabre > Signed-off-by: Daniel Borkmann > Link: https://lore.kernel.org/netdev/CAJPywTJqP34cK20iLM5YmUMz9KXQOdu1-+BZrGMAGgLuBWz7fg@mail.gmail.com/T/ [...] MBR, Sergei