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=-5.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,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 CF786C43603 for ; Tue, 10 Dec 2019 00:10:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EEB02071E for ; Tue, 10 Dec 2019 00:10:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="cUcjvQrL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727376AbfLJAKQ (ORCPT ); Mon, 9 Dec 2019 19:10:16 -0500 Received: from mail-pf1-f193.google.com ([209.85.210.193]:32877 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726495AbfLJAKQ (ORCPT ); Mon, 9 Dec 2019 19:10:16 -0500 Received: by mail-pf1-f193.google.com with SMTP id y206so8094318pfb.0 for ; Mon, 09 Dec 2019 16:10:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=w90N60kf2vkfXZNvEFDEc4sn4v4O0mdh7Peic2U0RJU=; b=cUcjvQrLB1c6A1YQUjmrEnuFAWry67dpxeGakaW1Vb9TToQ2P7pfElXXpgd0MJ3BWb txLl/L/xD3YcoSVqq5OguXzcyVSjxCNdmlat8DusUQ+d3Ll0pHLUdPxLHueRr79knhW3 KAbL57XlOgHjt4OeJsg8m8p5HG7ZqETgi4fRk= 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:references :mime-version:content-disposition:in-reply-to; bh=w90N60kf2vkfXZNvEFDEc4sn4v4O0mdh7Peic2U0RJU=; b=uXU5cIIPHF3vBdUGudSjw1Y32hBj9OMmXCZBLgveVcBarla94WhMsaevrHEb1QuER6 AKvaxdJWATWTwOEuQFI1hTesCb6I4hD4j36ivJYHlOqXR7ibcDKxiRY1cBOOEkWbF3d8 irTN4TFHd6aL3OegfYFkZhVGWMkKaSkAwFpuuhLKupbbEjuG6kMkse7mAAU0caE/ncWh n2lvCo35eKQfRab4jSzWJWnfwdmqZN34aIs7SNnUCE0nXCyQrFOFRRiXOBb3iuQcVa/l wIPx2F/1OxassP5U7M98CpfzU3tjTvEbX6K/v4zaiLiji3XswsCmz1eaWCMcnVpQlJZD BAQA== X-Gm-Message-State: APjAAAWhkSUTuhmJJCAYy4Zjk9NesdXcGZBc8i2fNaQuh7vviMimc1e3 cKOMH/bvns+58lJF/r2ZAv+kwg== X-Google-Smtp-Source: APXvYqyl+o2nEiFfnTVCnxDru2CZs4MZSIEyWUVZGB2xVf09IR2+sLWUb8qQIrzHre089xyxLt4uJQ== X-Received: by 2002:a63:5219:: with SMTP id g25mr21171426pgb.321.1575936615493; Mon, 09 Dec 2019 16:10:15 -0800 (PST) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id y38sm654427pgk.33.2019.12.09.16.10.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Dec 2019 16:10:14 -0800 (PST) Date: Mon, 9 Dec 2019 16:10:13 -0800 From: Kees Cook To: syzbot Cc: acme@kernel.org, akpm@linux-foundation.org, arnd@arndb.de, bp@alien8.de, bp@suse.de, christian@brauner.io, cyphar@cyphar.com, dhowells@redhat.com, dvyukov@google.com, ebiederm@xmission.com, frederic@kernel.org, gustavo@embeddedor.com, hpa@zytor.com, jannh@google.com, jolsa@redhat.com, linux-kernel@vger.kernel.org, luto@kernel.org, mark.rutland@arm.com, mhiramat@kernel.org, mingo@kernel.org, mingo@redhat.com, mtk.manpages@gmail.com, namhyung@kernel.org, oleg@redhat.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, x86@kernel.org Subject: Re: WARNING in arch_install_hw_breakpoint Message-ID: <201912091608.1DA5B7865F@keescook> References: <000000000000639f6a0584d11b82@google.com> <0000000000007f8bf6059932fe10@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000000000007f8bf6059932fe10@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 08, 2019 at 07:33:00AM -0800, syzbot wrote: > syzbot suspects this bug was fixed by commit: > > commit b3e5838252665ee4cfa76b82bdf1198dca81e5be > Author: Christian Brauner > Date: Wed Mar 27 12:04:15 2019 +0000 > > clone: add CLONE_PIDFD That seems ... unlikely? I suspect this WARN should just be pr_err or something: if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot")) return -EBUSY; If it's reachable through normal code, it shouldn't be possible to trip a WARN. -Kees > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1268377ae00000 > start commit: fd1f297b Merge tag 'drm-fixes-2019-03-22' of git://anongit.. > git tree: upstream > kernel config: https://syzkaller.appspot.com/x/.config?x=9a31fb246de2a622 > dashboard link: https://syzkaller.appspot.com/bug?extid=370a6b0f11867bf13515 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15d8bd93200000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15439f27200000 > > If the result looks correct, please mark the bug fixed by replying with: > > #syz fix: clone: add CLONE_PIDFD > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection -- Kees Cook