From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/13534 Path: news.gmane.org!.POSTED!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: aio_cancel segmentation fault for in progress write requests Date: Fri, 7 Dec 2018 15:14:53 -0500 Message-ID: <20181207201453.GH23599@brightrain.aerifal.cx> References: <20181207154419.GD23599@brightrain.aerifal.cx> <20181207165217.GE23599@brightrain.aerifal.cx> <54b4d253-1660-3207-5d59-f23f1c25b2b9@adelielinux.org> <20181207182650.GF23599@brightrain.aerifal.cx> <87h8fpaypx.fsf@oldenburg2.str.redhat.com> 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 1544213581 30302 195.159.176.226 (7 Dec 2018 20:13:01 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 7 Dec 2018 20:13:01 +0000 (UTC) User-Agent: Mutt/1.5.21 (2010-09-15) To: musl@lists.openwall.com Original-X-From: musl-return-13550-gllmg-musl=m.gmane.org@lists.openwall.com Fri Dec 07 21:12:57 2018 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 1gVMUb-0007jn-6B for gllmg-musl@m.gmane.org; Fri, 07 Dec 2018 21:12:57 +0100 Original-Received: (qmail 31964 invoked by uid 550); 7 Dec 2018 20:15:05 -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 31938 invoked from network); 7 Dec 2018 20:15:05 -0000 Content-Disposition: inline In-Reply-To: <87h8fpaypx.fsf@oldenburg2.str.redhat.com> Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:13534 Archived-At: On Fri, Dec 07, 2018 at 09:06:18PM +0100, Florian Weimer wrote: > * Rich Felker: > > > I don't think so. I'm concerned that it's a stack overflow, and that > > somehow the kernel folks have managed to break the MINSIGSTKSZ ABI. > > Probably: > > > > > It's a nasty CPU backwards compatibility problem. Some of the > suggestions I made to work around this are simply wrong; don't take them > too seriously. > > Nowadays, the kernel has a way to disable the %zmm registers, but it > unfortunately does not reduce the save area size. How large is the saved context with the %zmm junk? I measured just ~768 bytes on normal x86_64 without it, and since 2048 is rounded up to a whole page (4096), overflow should not happen until the signal context is something like 3.5k (allowing ~512 bytes for TCB (~128) and 2 simple call frames). Rich