From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754540AbbFSKGp (ORCPT ); Fri, 19 Jun 2015 06:06:45 -0400 Received: from eddie.linux-mips.org ([148.251.95.138]:59315 "EHLO cvs.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751571AbbFSKGh (ORCPT ); Fri, 19 Jun 2015 06:06:37 -0400 Date: Fri, 19 Jun 2015 12:06:26 +0200 From: Ralf Baechle To: Rich Felker Cc: Matthias Schiffer , musl@lists.openwall.com, linux-mips@linux-mips.org, "linux-kernel@vger.kernel.org" Subject: Re: [musl] musl-libc/MIPS: detached thread exit broken since kernel commit 46e12c07b Message-ID: <20150619100626.GB29960@linux-mips.org> References: <55837978.7020801@universe-factory.net> <20150619025032.GR1173@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150619025032.GR1173@brightrain.aerifal.cx> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 18, 2015 at 10:50:32PM -0400, Rich Felker wrote: > This is kernel ABI breakage that should be fixed -- people running old > kernel versions with old musl binaries might suffer a regression when > upgrading, and perhaps more importantly the failure mode is just > really bad. But I think we can also work around it on the userspace > side in musl by pointing the stack pointer at some rodata (or even at > pc, e.g. copying $25 to $sp) before making the syscall. Just to be on the safe side, make sure it is something that's readable. Core might me mapped execute-only, that is not readable and that is a feature which the affected kernels do support on suitable hardware. Ralf