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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 478A3C432C0 for ; Mon, 18 Nov 2019 18:44:12 +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 177BC222C2 for ; Mon, 18 Nov 2019 18:44:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="X8fUVoVf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 177BC222C2 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]:38148 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iWm0R-0006tW-7o for qemu-devel@archiver.kernel.org; Mon, 18 Nov 2019 13:44:11 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40215) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iWlyy-00064l-QK for qemu-devel@nongnu.org; Mon, 18 Nov 2019 13:42:41 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iWlyw-0000sE-TH for qemu-devel@nongnu.org; Mon, 18 Nov 2019 13:42:39 -0500 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:43243 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iWlyw-0000rc-OK for qemu-devel@nongnu.org; Mon, 18 Nov 2019 13:42:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574102557; 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=cEdJqtRj7FvPjTb3Rr2nH1P95ASTUqg5fccA2ZxkeG8=; b=X8fUVoVfGddNRRd6cdTjVPPhXcXpJ2SaqrAw0NtSIpGB19R+iALR4bP+YiguPRgqx9Nzna ffUQVQMy2X7Z5MarCQyeWEI4OFIFXQ7g/81YqlEDaAlHf5aUmuTlIciMljwnOzDX1pSJhP T3cYgjVRpEWZolIYxKEEnBfsLfkuXa8= 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-380-yLYeoTojOdWw9CZHCSC9aQ-1; Mon, 18 Nov 2019 13:42:36 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 512368018A3; Mon, 18 Nov 2019 18:42:34 +0000 (UTC) Received: from [10.3.116.221] (ovpn-116-221.phx2.redhat.com [10.3.116.221]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3EC291D9; Mon, 18 Nov 2019 18:42:26 +0000 (UTC) Subject: Re: [PATCH v2 3/3] trace: Forbid dynamic field width in event format From: Eric Blake To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-devel@nongnu.org References: <20191108144042.30245-1-philmd@redhat.com> <20191108144042.30245-4-philmd@redhat.com> <191fbe18-73b2-4d22-5540-8775688166a8@redhat.com> Organization: Red Hat, Inc. Message-ID: Date: Mon, 18 Nov 2019 12:42:25 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <191fbe18-73b2-4d22-5540-8775688166a8@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-MC-Unique: yLYeoTojOdWw9CZHCSC9aQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.61 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: Kevin Wolf , Aleksandar Markovic , qemu-block@nongnu.org, qemu-trivial@nongnu.org, Max Reitz , Stefan Hajnoczi , Aleksandar Rikalo , Aurelien Jarno Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11/8/19 10:07 AM, Eric Blake wrote: > On 11/8/19 8:40 AM, Philippe Mathieu-Daud=C3=A9 wrote: >> Since not all trace backends support dynamic field width in >> format (dtrace via stap does not), forbid them. >> >> Add a check to refuse field width in new formats: >> >=20 >> +++ b/scripts/tracetool/__init__.py >> @@ -206,6 +206,7 @@ class Event(object): >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 "\s*" >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 "(?:(?:(= ?P\".+),)?\s*(?P\".+))?" >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 "\s*") >> +=C2=A0=C2=A0=C2=A0 _DFWRE =3D re.compile(".*(%0?\*).*") >=20 > The use of leading and trailing .* is pointless if the RE itself is used= =20 > unanchored and where you only care if the () matched. Following up on this (based on an IRC conversation): re.match _is_ anchored by default, while re.search is unanchored >=20 > This doesn't catch all valid uses of * in a printf format.=C2=A0 Better m= ight=20 > be something like: >=20 > _DFWRE =3D re.compile("%[\d\.\- +#']*\*") >=20 > which matches only if there is a %, any number of characters that can=20 > form a printf flag, as well as a numeric field width but dynamic precisio= n. >=20 >=20 >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if Event._DFWRE.match(fmt): Or put differently, if you want to drop the .* from the compiled regex,=20 then you need to use .search(fmt) here rather than .match(fmt). --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org