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=-1.5 required=3.0 tests=HK_RANDOM_FROM, MAILING_LIST_MULTI,SPF_HELO_NONE,USER_AGENT_SANE_1 autolearn=no 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 EF7FBC433E0 for ; Sun, 24 May 2020 02:23:52 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C005520735 for ; Sun, 24 May 2020 02:23:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C005520735 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bu.edu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:55606 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jcgIp-0002yx-RH for qemu-devel@archiver.kernel.org; Sat, 23 May 2020 22:23:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:55502) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jcgI9-0002RM-OD for qemu-devel@nongnu.org; Sat, 23 May 2020 22:23:09 -0400 Received: from relay68.bu.edu ([128.197.228.73]:53568) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jcgI7-0003eM-S8 for qemu-devel@nongnu.org; Sat, 23 May 2020 22:23:09 -0400 X-Envelope-From: alxndr@bu.edu X-BU-AUTH: mozz.bu.edu [128.197.127.33] Received: from BU-AUTH (localhost.localdomain [127.0.0.1]) (authenticated bits=0) by relay68.bu.edu (8.14.3/8.14.3) with ESMTP id 04O2Malm030667 (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Sat, 23 May 2020 22:22:39 -0400 Date: Sat, 23 May 2020 22:22:36 -0400 From: Alexander Bulekov To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [RFC PATCH v2] hw/i386/vmport: Allow QTest use without crashing Message-ID: <20200524022230.rij2ehcmerhoj3ur@mozz.bu.edu> References: <20200518103113.9882-1-f4bug@amsat.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200518103113.9882-1-f4bug@amsat.org> User-Agent: NeoMutt/20180716 Received-SPF: pass client-ip=128.197.228.73; envelope-from=alxndr@bu.edu; helo=relay68.bu.edu X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/23 22:23:05 X-ACL-Warn: Detected OS = Linux 2.6.x X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, HK_RANDOM_ENVFROM=0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 200518 1231, Philippe Mathieu-Daudé wrote: > Trying libFuzzer on the vmport device, we get: > > AddressSanitizer:DEADLYSIGNAL > ================================================================= > ==29476==ERROR: AddressSanitizer: SEGV on unknown address 0x000000008840 (pc 0x56448bec4d79 bp 0x7ffeec9741b0 sp 0x7ffeec9740e0 T0) > ==29476==The signal is caused by a READ memory access. > #0 0x56448bec4d78 in vmport_ioport_read (qemu-fuzz-i386+0x1260d78) > #1 0x56448bb5f175 in memory_region_read_accessor (qemu-fuzz-i386+0xefb175) > #2 0x56448bb30c13 in access_with_adjusted_size (qemu-fuzz-i386+0xeccc13) > #3 0x56448bb2ea27 in memory_region_dispatch_read1 (qemu-fuzz-i386+0xecaa27) > #4 0x56448bb2e443 in memory_region_dispatch_read (qemu-fuzz-i386+0xeca443) > #5 0x56448b961ab1 in flatview_read_continue (qemu-fuzz-i386+0xcfdab1) > #6 0x56448b96336d in flatview_read (qemu-fuzz-i386+0xcff36d) > #7 0x56448b962ec4 in address_space_read_full (qemu-fuzz-i386+0xcfeec4) > > X86CPU is NULL because QTest accelerator does not use CPU. > Fix by returning default values when QTest accelerator is used. > Ah - it was QTest. Thank you for this - I would always run into this crash within a second of fuzzing. -Alex