Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752488AbbKIOQF (ORCPT ); Mon, 9 Nov 2015 09:16:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50938 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751509AbbKIOP7 (ORCPT ); Mon, 9 Nov 2015 09:15:59 -0500 Date: Mon, 9 Nov 2015 16:12:04 +0100 From: Oleg Nesterov To: Andy Lutomirski Cc: "Amanieu d'Antras" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Linux MIPS Mailing List , linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, "linux-s390@vger.kernel.org" , sparclinux@vger.kernel.org, Linux FS Devel , linux-arch , Linux API , Kenton Varda Subject: Re: [PATCH v2 00/20] Fix handling of compat_siginfo_t Message-ID: <20151109151204.GA10760@redhat.com> References: <1446684640-4112-1-git-send-email-amanieu@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1826 Lines: 47 On 11/07, Andy Lutomirski wrote: > > On Wed, Nov 4, 2015 at 4:50 PM, Amanieu d'Antras wrote: > > One issue that isn't resolved in this series is sending signals between a 32-bit > > process and 64-bit process. Sending a si_int will work correctly, but a si_ptr > > value will likely get corrupted due to the different layouts of the 32-bit and > > 64-bit siginfo_t structures. > > This is so screwed up it's not even funny. Agreed, > A 64-bit big-endian compat calls rt_sigqueueinfo. It passes in (among > other things) a sigval_t. The kernel can choose to interpret it I always thought that the kernel should not interpret it at all. And indeed, copy_siginfo_to_user() does if (from->si_code < 0) return __copy_to_user(to, from, sizeof(siginfo_t)) probably copy_siginfo_to_user32() should do something similar, at least it should not truncate ->si_code it it is less than zero. Not sure what signalfd_copyinfo() should do. But perhaps I was wrong, I failed to find man sigqueueinfo, and man sigqueue() documents that it passes sigval_t. > BTW, x86 has its own set of screwups here. Somehow cr2 and error_code > ended up as part of ucontext instead of siginfo, which makes > absolutely no sense to me and bloats task_struct. Yes, and probably ->ip should have been the part of siginfo too. Say, if you get SIGBUS you can't trust sc->ip if another signal was dequeued before SIGBUS, in this case sc->ip will point to the handler of that another signal. That is why we have SYNCHRONOUS_MASK and it helps, but still this doesn't look nice. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/