From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 975DB1F466 for ; Tue, 21 Jan 2020 08:57:35 +0000 (UTC) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:cc:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; q=dns; s=default; b=I4bAhPy/lWEK2Q1i 12TC+jGlsG5WAd641G0lgLZuo0NL12L0qVbx03FgOwCOWOTTcLNqIJ0yVWe8nCfP HzgiS0BSzypJ2tiSr4YFjyt2hMvdkiF/nKODLm1E5VrSbRdijmOL3Y/+VD6cN69P 7tC0QM3K5hLQ77R7w+tRMKgIxrU= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:subject:to:cc:references:from:message-id:date :mime-version:in-reply-to:content-type :content-transfer-encoding; s=default; bh=LYOyUp7af5qA21yOf2nqOD nxbA0=; b=q3hu9l9W0l5TDpmT8bPRlPTHNf1WW9PwClHCsGQpwlI8ICcoAc9a9p 2zT2ez6W/vLeFjkxmsk3qDmlcHlPgody+7INUdteOJk/FES7cpIs3VwjwGhrMPe9 IoeDIxnUjVdVuAMyIbEGa49sINuuTrKFVBqTqob4Bgl4R1HqSp/qo= Received: (qmail 27556 invoked by alias); 21 Jan 2020 08:57:32 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 27543 invoked by uid 89); 21 Jan 2020 08:57:32 -0000 Authentication-Results: sourceware.org; auth=none X-HELO: zimbra.cs.ucla.edu Subject: Re: question about regex To: liqingqing , =?UTF-8?Q?Tim_R=c3=bchsen?= Cc: libc-alpha@sourceware.org, Florian Weimer , Carlos O'Donell , Hushiyuan , Liusirui References: <05dfac46-6cf3-1f5d-14e7-3c8b07b2093e@cs.ucla.edu> <377311fb-fdf3-6467-3b48-28404d8c3326@huawei.com> <034194cc-908b-d29f-5ee7-9cf273868ff0@cs.ucla.edu> <10479390-8a29-07f3-2d80-ebc7c340fe64@huawei.com> From: Paul Eggert Message-ID: Date: Tue, 21 Jan 2020 00:57:18 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <10479390-8a29-07f3-2d80-ebc7c340fe64@huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit On 1/20/20 5:15 PM, liqingqing wrote: > The proposal is that I want to find a way to fix the bug#24269(infinite loop bugs). Why is this urgent? Even if you fix this particular bug correctly (instead of merely putting in an arbitrary backtrack limit), there are lots of ways to make the regex code explode exponentially and I don't see the practical difference between doing that and looping forever.