From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13108 invoked by alias); 22 Mar 2013 17:59:51 -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 13091 invoked by uid 89); 22 Mar 2013 17:59:43 -0000 X-Spam-SWARE-Status: No, score=-8.6 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.1 Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.84/v0.84-167-ge50287c) with ESMTP; Fri, 22 Mar 2013 17:59:41 +0000 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r2MHxdLR002502 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 22 Mar 2013 13:59:39 -0400 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id r2MHxcjX001834; Fri, 22 Mar 2013 13:59:38 -0400 Message-ID: <514C9C0A.9090305@redhat.com> Date: Fri, 22 Mar 2013 20:13:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130311 Thunderbird/17.0.4 MIME-Version: 1.0 To: Keith Seitz CC: "gdb-patches@sourceware.org ml" Subject: Re: [RFA] Stop leaking extra_string References: <514A08A5.6020504@redhat.com> <514A0A9E.1090105@redhat.com> <514A358F.3080403@redhat.com> In-Reply-To: <514A358F.3080403@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-SW-Source: 2013-03/txt/msg00859.txt.bz2 Thanks for the analysis, Keith. On 03/20/2013 10:17 PM, Keith Seitz wrote: > On 03/20/2013 12:14 PM, Pedro Alves wrote: > >> When we get to this bit in addr_string_to_sals (called through >> breakpoint_re_set_default): >> >> if (cond_string) >> b->cond_string = cond_string; >> b->thread = thread; >> b->task = task; >> if (extra_string) >> b->extra_string = extra_string; >> b->condition_not_parsed = 0; >> >> Is b->extra_string always NULL here, or could we be >> leaking it here too? > > I don't think that is possible right now. > > When extra_string is set by find_condition_and_thread, init_breakpoint_sal (called from ops->create_breakpoints_sal) will error if extra_string isn't NULL (for non-dprintf breakpoints). > > So the only way to get extra_string != NULL in breakpoint_re_set is by setting a pending dprintf breakpoint, which doesn't even work because any pending breakpoint will automatically have extra_string set to NULL in create_breakpoint. > > But this is all largely academic for two reasons: 1) Adding an xfree there wouldn't hurt; 2) I'm going to submit a patch to do just that because I am changing it so that extra_string could be set. :-) :-) It's fine with me to not bother. An assert would be fine too, and it might be better. Still looking at addr_string_to_sals, it looks like if (cond_string) b->cond_string = cond_string; b->thread = thread; b->task = task; if (extra_string) b->extra_string = extra_string; the "if (extra_string)" test looks unnecessary then. I wonder if the "cond_string" one has any meaning. It reads as if the code is trying to preserve the original condition string if resolving a pending breakpoint ends up finding no condition was really there to begin with. b->cond_string does leak here, though, I think? Unlike b->extra_string, b->cond_string isn't always left NULL when create_breakpoint creates a pending breakpoint: b->addr_string = copy_arg; if (parse_condition_and_thread) b->cond_string = NULL; else { /* Create a private copy of condition string. */ if (cond_string) { cond_string = xstrdup (cond_string); make_cleanup (xfree, cond_string); } b->cond_string = cond_string; } b->extra_string = NULL; b->ignore_count = ignore_count; b->disposition = tempflag ? disp_del : disp_donttouch; b->condition_not_parsed = 1; and we end up with b->condition_not_parsed set even in the !parse_condition_and_thread case. That means a later reset ends up in the addr_string_to_sals bit in question, and overwrites the b->cond_string set here then. That doesn't look right. Hmm, wait. I'm having a déjà vu. I was working on something around pending breakpoints and the condition a while ago, but never finished it. Damn, I forget all the details now: http://sourceware.org/ml/gdb-patches/2012-08/msg00092.html > I've committed my original patch. Thank you for taking a look at this. Thanks. -- Pedro Alves