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=-5.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 80FBCC54FD0 for ; Thu, 23 Apr 2020 05:18:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5E0E72087E for ; Thu, 23 Apr 2020 05:18:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ZnsO8fVk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726454AbgDWFSN (ORCPT ); Thu, 23 Apr 2020 01:18:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1725867AbgDWFSM (ORCPT ); Thu, 23 Apr 2020 01:18:12 -0400 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 928EEC03C1AB; Wed, 22 Apr 2020 22:18:11 -0700 (PDT) Received: by mail-pg1-x542.google.com with SMTP id o15so2334590pgi.1; Wed, 22 Apr 2020 22:18:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to:user-agent; bh=qCBsa1pJlvt7zkIr/3FJFH5RgTV4mszszMc7Yftm9j8=; b=ZnsO8fVk0++VtXCgCcGrNVzqJZq0AoklIMWuOpbYiwXhATkktI9CbfqB4yRA0SItP7 azBW1r6Jb5iyoAiziDIDLIuEYdQ4M97hJ/Sf/rfI92FjaZZ2S/q9tzL2QhP2j7J2egpf CbxWrli3xBhkp6H20ZA2qRN7J2jVYTeh4GVyoJ11H2yCZtvohehqoD1QwPvpFLH7Ka4J oqowfGJg4MNNxmHVCxWKhClqlf4InXXnWLzk4c3jbHm0H4RQyGW1999uONr1HVCP9F1M bnjQ02lVGrC2IUMkYYiiJebH93C7ygcXHo1kP3G/fFgNFcLyRgVNSB52JQ5Qq2oxpqX7 4hxw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to:user-agent; bh=qCBsa1pJlvt7zkIr/3FJFH5RgTV4mszszMc7Yftm9j8=; b=QF4pwUbLkNhVu+vKs2wqZr9JmqCAYpvfgzViUj5yNNONJtIDaTdP6WaHhgwy7Ixn+X T0vPLa5D4Wwz79atWE/WIgvLld4SYjgXTBYlh2h3TLFZteianxkF6DDGejYs5jg7ACSX qTXj2k+nQ5kLEDlFIDL3tstwpLLFZzLGZZVi2PJsPeIQyA1Jk8Ax21kHOGW4/kXwpmpJ WNCHuQmbrK2foG7R2JFD/oX+onGlQEJ4WIdSwOxop1QeFG80lpjCOR4J9b3L6Rg82D6S q4/cQ2twMP5UMclUbatr6uPnlpyjzaCOmYqs/7n1BJFmYFfA2S4thrzSCd375z0lV+Vv ntKQ== X-Gm-Message-State: AGi0Pub1qdT7OAE3l/dwKVH47lXSALGTqpS/ZdVg8nTzSzK+wW5VMbHc UusTehVnzXPCeU0K0KkEbv8= X-Google-Smtp-Source: APiQypLKYZo7sa83+KriCNF74gBjCVlbbw0qbHAGVoV3iMxICiijUV8rmcy6yRTFdCDjoeefv36pdQ== X-Received: by 2002:a63:2166:: with SMTP id s38mr2306743pgm.369.1587619091150; Wed, 22 Apr 2020 22:18:11 -0700 (PDT) Received: from udknight.localhost ([183.250.89.86]) by smtp.gmail.com with ESMTPSA id k10sm1300719pfa.163.2020.04.22.22.18.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Apr 2020 22:18:10 -0700 (PDT) Received: from udknight.localhost (localhost [127.0.0.1]) by udknight.localhost (8.14.9/8.14.4) with ESMTP id 03N4AMGY001222; Thu, 23 Apr 2020 12:10:22 +0800 Received: (from root@localhost) by udknight.localhost (8.14.9/8.14.9/Submit) id 03N4AGAg001218; Thu, 23 Apr 2020 12:10:16 +0800 Date: Thu, 23 Apr 2020 12:10:16 +0800 From: Wang YanQing To: Luke Nelson Cc: bpf@vger.kernel.org, Brian Gerst , Luke Nelson , Xi Wang , "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH bpf v2 2/2] bpf, x86_32: Fix clobbering of dst for BPF_JSET Message-ID: <20200423041016.GA1153@udknight> Mail-Followup-To: Wang YanQing , Luke Nelson , bpf@vger.kernel.org, Brian Gerst , Luke Nelson , Xi Wang , "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200422173630.8351-1-luke.r.nels@gmail.com> <20200422173630.8351-2-luke.r.nels@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200422173630.8351-2-luke.r.nels@gmail.com> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Wed, Apr 22, 2020 at 10:36:30AM -0700, Luke Nelson wrote: > The current JIT clobbers the destination register for BPF_JSET BPF_X > and BPF_K by using "and" and "or" instructions. This is fine when the > destination register is a temporary loaded from a register stored on > the stack but not otherwise. > > This patch fixes the problem (for both BPF_K and BPF_X) by always loading > the destination register into temporaries since BPF_JSET should not > modify the destination register. > > This bug may not be currently triggerable as BPF_REG_AX is the only > register not stored on the stack and the verifier uses it in a limited > way. > > Fixes: 03f5781be2c7b ("bpf, x86_32: add eBPF JIT compiler for ia32") > Signed-off-by: Xi Wang > Signed-off-by: Luke Nelson Acked-by: Wang YanQing