From patchwork Mon Oct 26 10:06:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Huth X-Patchwork-Id: 11856309 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C3111921 for ; Mon, 26 Oct 2020 10:18:47 +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 5BCFB22242 for ; Mon, 26 Oct 2020 10:18:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ijNmUxBB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5BCFB22242 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:38030 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kWzaQ-0001U0-27 for patchwork-qemu-devel@patchwork.kernel.org; Mon, 26 Oct 2020 06:18:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38972) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kWzPI-0002o0-4A for qemu-devel@nongnu.org; Mon, 26 Oct 2020 06:07:16 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:26364) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kWzPD-0006kD-3Z for qemu-devel@nongnu.org; Mon, 26 Oct 2020 06:07:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603706829; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:content-type:content-type:in-reply-to:in-reply-to: references:references; bh=rPj1DFhuZ+EQW7IN7zl+uQqA9OVlS+YiYiVtbtyvbdg=; b=ijNmUxBBbgZ0H2T/tMGegC3Si7L9/IW0yoUCrayqrTZJO3xMWM9e1uUUNett3W+I1e5xFD 6xdYih4W78iWthTqzwhzS8YhnAqxMBvwnXN5MTrk4tu8m+NI7YSExFt8eQeX3hFVDlN/AT 9MLabP3/ZSrwJUtflcyYrtDtG4eM6tQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-99-qwwkHxQtPmOndVfO_KXOKw-1; Mon, 26 Oct 2020 06:07:07 -0400 X-MC-Unique: qwwkHxQtPmOndVfO_KXOKw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9C30F10E2185; Mon, 26 Oct 2020 10:07:06 +0000 (UTC) Received: from thuth.com (ovpn-112-104.ams2.redhat.com [10.36.112.104]) by smtp.corp.redhat.com (Postfix) with ESMTP id 922E88B842; Mon, 26 Oct 2020 10:07:05 +0000 (UTC) From: Thomas Huth To: qemu-devel@nongnu.org, Peter Maydell Subject: [PULL 20/31] fuzz: Add instructions for using generic-fuzz Date: Mon, 26 Oct 2020 11:06:21 +0100 Message-Id: <20201026100632.212530-21-thuth@redhat.com> In-Reply-To: <20201026100632.212530-1-thuth@redhat.com> References: <20201026100632.212530-1-thuth@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=thuth@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/26 02:39:09 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no 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: Alexander Bulekov Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Alexander Bulekov Reviewed-by: Darren Kenny Signed-off-by: Alexander Bulekov Message-Id: <20201023150746.107063-13-alxndr@bu.edu> Signed-off-by: Thomas Huth --- docs/devel/fuzzing.txt | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/docs/devel/fuzzing.txt b/docs/devel/fuzzing.txt index 96d71c94d7..03585c1a9b 100644 --- a/docs/devel/fuzzing.txt +++ b/docs/devel/fuzzing.txt @@ -125,6 +125,45 @@ provided by libfuzzer. Libfuzzer passes a byte array and length. Commonly the fuzzer loops over the byte-array interpreting it as a list of qtest commands, addresses, or values. +== The Generic Fuzzer == +Writing a fuzz target can be a lot of effort (especially if a device driver has +not be built-out within libqos). Many devices can be fuzzed to some degree, +without any device-specific code, using the generic-fuzz target. + +The generic-fuzz target is capable of fuzzing devices over their PIO, MMIO, +and DMA input-spaces. To apply the generic-fuzz to a device, we need to define +two env-variables, at minimum: + +QEMU_FUZZ_ARGS= is the set of QEMU arguments used to configure a machine, with +the device attached. For example, if we want to fuzz the virtio-net device +attached to a pc-i440fx machine, we can specify: +QEMU_FUZZ_ARGS="-M pc -nodefaults -netdev user,id=user0 \ + -device virtio-net,netdev=user0" + +QEMU_FUZZ_OBJECTS= is a set of space-delimited strings used to identify the +MemoryRegions that will be fuzzed. These strings are compared against +MemoryRegion names and MemoryRegion owner names, to decide whether each +MemoryRegion should be fuzzed. These strings support globbing. For the +virtio-net example, we could use QEMU_FUZZ_OBJECTS= + * 'virtio-net' + * 'virtio*' + * 'virtio* pcspk' (Fuzz the virtio devices and the PC speaker...) + * '*' (Fuzz the whole machine) + +The "info mtree" and "info qom-tree" monitor commands can be especially useful +for identifying the MemoryRegion and Object names used for matching. + +As a generic rule-of-thumb, the more MemoryRegions/Devices we match, the greater +the input-space, and the smaller the probability of finding crashing inputs for +individual devices. As such, it is usually a good idea to limit the fuzzer to +only a few MemoryRegions. + +To ensure that these env variables have been configured correctly, we can use: + +./qemu-fuzz-i386 --fuzz-target=generic-fuzz -runs=0 + +The output should contain a complete list of matched MemoryRegions. + = Implementation Details = == The Fuzzer's Lifecycle ==