From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/11637 Path: news.gmane.org!.POSTED!not-for-mail From: Alexander Monakov Newsgroups: gmane.linux.lib.musl.general Subject: Re: [RFC PATCH] Allow annotating calloc for Valgrind Date: Sun, 2 Jul 2017 19:16:15 +0300 (MSK) Message-ID: References: <20170629225614.19061-1-amonakov@ispras.ru> <20170629232032.GH1627@brightrain.aerifal.cx> <20170629235624.GI1627@brightrain.aerifal.cx> <20170702143539.GK1627@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Trace: blaine.gmane.org 1499012193 29365 195.159.176.226 (2 Jul 2017 16:16:33 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 2 Jul 2017 16:16:33 +0000 (UTC) User-Agent: Alpine 2.20.13 (LNX 116 2015-12-14) To: musl@lists.openwall.com Original-X-From: musl-return-11650-gllmg-musl=m.gmane.org@lists.openwall.com Sun Jul 02 18:16:27 2017 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.84_2) (envelope-from ) id 1dRhXu-0007Ff-W6 for gllmg-musl@m.gmane.org; Sun, 02 Jul 2017 18:16:27 +0200 Original-Received: (qmail 14255 invoked by uid 550); 2 Jul 2017 16:16:30 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 14234 invoked from network); 2 Jul 2017 16:16:30 -0000 In-Reply-To: <20170702143539.GK1627@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:11637 Archived-At: On Sun, 2 Jul 2017, Rich Felker wrote: > I'm not sure it makes sense to do -- is there a good reason dynamic > linking can't be used when debugging memory errors? Surely some apps > (especially proprietary ones) might be shipped as static binaries, but > these will likely lack debugging symbols anyway. Perhaps the project is hard to rebuild with shared libc.so, for reasons like using linker functionality (e.g. --wrap, linker scripts) that does not have direct equivalents outside of fully-static linking. But in any case, even if there are doubts as to *why* people do it, we know for certain that people hit this issue - there were two independent reports on the mailing list this month. It would be nice to come up with some kind of "canonical answer" for those situations - is it going to be "just don't use static linking"? > There are also fundamental limits to the correctness of any approach > that uses static linking, since too much information has already been > lost. It's calling the _name_ malloc, realloc, or free (not the code > at the location; think aliases etc.) that must have the allocation > semantics. Even if nothing weird is happening with aliases at the libc > implementation level, the compiler could do major transformations with > IPA (especially with LTO) that end up resulting in code being shared > in unexpected ways. Are you sure the same theory doesn't apply with shared libc.so? When you call malloc internally in libc.so (e.g. printf->...->realloc), you're not calling it via a dynamic relocation. Alexander