From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 86177 invoked by alias); 9 Oct 2018 10:44:42 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 86097 invoked by uid 89); 9 Oct 2018 10:44:34 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=dies, disturbing X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 09 Oct 2018 10:44:33 +0000 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0217C227BF; Tue, 9 Oct 2018 10:44:32 +0000 (UTC) Received: from [127.0.0.1] (ovpn04.gateway.prod.ext.ams2.redhat.com [10.39.146.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id C7F6A6E6FD; Tue, 9 Oct 2018 10:44:30 +0000 (UTC) Subject: Re: [PATCH v2 00/10] Undefined Behavior Sanitizer, this time with docs To: Joel Brobecker , John Baldwin References: <20181002044420.17628-1-tom@tromey.com> <8df7a2b9-800a-5a70-1075-e687145c9394@FreeBSD.org> <20181008202245.GC2993@adacore.com> Cc: Tom Tromey , gdb-patches@sourceware.org From: Pedro Alves Message-ID: <4afd7c11-d43d-191a-201f-3ed3db7da38e@redhat.com> Date: Tue, 09 Oct 2018 10:44:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181008202245.GC2993@adacore.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-10/txt/msg00205.txt.bz2 On 10/08/2018 09:22 PM, Joel Brobecker wrote: >> FWIW, I built GDB master today and ubsan (from LLVM, not GCC) flagged a >> use of obstack_blank_fast() in minsyms.c with a negative offset (used to >> shrink an obstack) when trying to do 'start' on /bin/ls: > > On my end, I am working on a resync of AdaCore's "head" version, > which would include this change as well. My testing shows that > it revealed some issues; I haven't had a chance to look into them yet > (next on my list today, hopefully), but this is making me think > there might be bona fide issues. Getting the location where things > are happening is pretty nice :). This also revealed PR 23743: https://sourceware.org/bugzilla/show_bug.cgi?id=23743 I think the side-effects are blocking/disturbing enough (GDB dies) that I think the best course of action is to temporarily disable the ubsan by default until these issues are fixed. Then try re-enabling again, rinse/repeat. Otherwise, as is, this is sort of imposing that the community prioritizes fixing these ubsan-exposed bugs, which I think is unreasonable. Thanks, Pedro Alves