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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 4FE5CC433E6 for ; Tue, 16 Mar 2021 21:22:07 +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 0659F64FA5 for ; Tue, 16 Mar 2021 21:22:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0659F64FA5 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+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57800 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMH8f-00065d-WE for qemu-devel@archiver.kernel.org; Tue, 16 Mar 2021 17:22:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51922) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMH2f-0005WS-Bz for qemu-devel@nongnu.org; Tue, 16 Mar 2021 17:15:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:35700) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lMH2X-0003VC-SJ for qemu-devel@nongnu.org; Tue, 16 Mar 2021 17:15:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615929344; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=i/DGdtQQ1rUmbZ91UH2o/Fu6b9EvArbb0mGvRXoUJYc=; b=Oau0YtiBwa7bjhW0Zfs5QSqrZAJ7gmimt+7PNzkmiOZrRjPZBxoOaXwHdvtP0GvSVjrTjc Yz5LN53adudEJiualByYKeUpTSXIlCIrWqS7OmhzH/Qhjh/MxABcIG4bXu4cg7qlKyOTj5 KmY9+JMRDXQ5gvwsH3mhB92jDGLizFo= 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-453-5wlDERFwNueVMz-1cwacPQ-1; Tue, 16 Mar 2021 17:15:42 -0400 X-MC-Unique: 5wlDERFwNueVMz-1cwacPQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DCE8F108BD07; Tue, 16 Mar 2021 21:15:40 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8DD6B610AF; Tue, 16 Mar 2021 21:15:40 +0000 (UTC) From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PULL 07/16] fuzz: add instructions for building reproducers Date: Tue, 16 Mar 2021 17:15:22 -0400 Message-Id: <20210316211531.1649909-8-pbonzini@redhat.com> In-Reply-To: <20210316211531.1649909-1-pbonzini@redhat.com> References: <20210316211531.1649909-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.25, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, 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 , Darren Kenny Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Alexander Bulekov We have several scripts that help build reproducers, but no documentation for how they should be used. Add some documentation Signed-off-by: Alexander Bulekov Reviewed-by: Darren Kenny Signed-off-by: Paolo Bonzini --- docs/devel/fuzzing.rst | 56 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/docs/devel/fuzzing.rst b/docs/devel/fuzzing.rst index 97797c4f8c..2749bb9bed 100644 --- a/docs/devel/fuzzing.rst +++ b/docs/devel/fuzzing.rst @@ -210,6 +210,62 @@ Build details: - The script responsible for building the fuzzers can be found in the QEMU source tree at ``scripts/oss-fuzz/build.sh`` +Building Crash Reproducers +----------------------------------------- +When we find a crash, we should try to create an independent reproducer, that +can be used on a non-fuzzer build of QEMU. This filters out any potential +false-positives, and improves the debugging experience for developers. +Here are the steps for building a reproducer for a crash found by the +generic-fuzz target. + +- Ensure the crash reproduces:: + + qemu-fuzz-i386 --fuzz-target... ./crash-... + +- Gather the QTest output for the crash:: + + QEMU_FUZZ_TIMEOUT=0 QTEST_LOG=1 FUZZ_SERIALIZE_QTEST=1 \ + qemu-fuzz-i386 --fuzz-target... ./crash-... &> /tmp/trace + +- Reorder and clean-up the resulting trace:: + + scripts/oss-fuzz/reorder_fuzzer_qtest_trace.py /tmp/trace > /tmp/reproducer + +- Get the arguments needed to start qemu, and provide a path to qemu:: + + less /tmp/trace # The args should be logged at the top of this file + export QEMU_ARGS="-machine ..." + export QEMU_PATH="path/to/qemu-system" + +- Ensure the crash reproduces in qemu-system:: + + $QEMU_PATH $QEMU_ARGS -qtest stdio < /tmp/reproducer + +- From the crash output, obtain some string that identifies the crash. This + can be a line in the stack-trace, for example:: + + export CRASH_TOKEN="hw/usb/hcd-xhci.c:1865" + +- Minimize the reproducer:: + + scripts/oss-fuzz/minimize_qtest_trace.py -M1 -M2 \ + /tmp/reproducer /tmp/reproducer-minimized + +- Confirm that the minimized reproducer still crashes:: + + $QEMU_PATH $QEMU_ARGS -qtest stdio < /tmp/reproducer-minimized + +- Create a one-liner reproducer that can be sent over email:: + + ./scripts/oss-fuzz/output_reproducer.py -bash /tmp/reproducer-minimized + +- Output the C source code for a test case that will reproduce the bug:: + + ./scripts/oss-fuzz/output_reproducer.py -owner "John Smith "\ + -name "test_function_name" /tmp/reproducer-minimized + +- Report the bug and send a patch with the C reproducer upstream + Implementation Details / Fuzzer Lifecycle ----------------------------------------- -- 2.26.2