From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53F9CC282CE for ; Tue, 4 Jun 2019 08:12:38 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2016724619 for ; Tue, 4 Jun 2019 08:12:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2016724619 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:48379 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hY4Yf-0002Zs-Dy for qemu-devel@archiver.kernel.org; Tue, 04 Jun 2019 04:12:37 -0400 Received: from eggs.gnu.org ([209.51.188.92]:58414) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hY4Xg-00021r-HP for qemu-devel@nongnu.org; Tue, 04 Jun 2019 04:11:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hY4Xd-0001bT-VQ for qemu-devel@nongnu.org; Tue, 04 Jun 2019 04:11:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52768) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hY4Xc-0001Yr-By; Tue, 04 Jun 2019 04:11:32 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3A0AF22389D; Tue, 4 Jun 2019 08:11:31 +0000 (UTC) Received: from [10.36.117.61] (ovpn-117-61.ams2.redhat.com [10.36.117.61]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6060A6063B; Tue, 4 Jun 2019 08:11:28 +0000 (UTC) To: Stefan Liebler , qemu-devel@nongnu.org References: <20190531145608.28183-1-david@redhat.com> <20190531145608.28183-3-david@redhat.com> <3bec7cf0-9be1-ea6f-7dbc-cbf95fd08293@linux.ibm.com> From: David Hildenbrand Openpgp: preference=signencrypt Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwX4EEwECACgFAljj9eoCGwMFCQlmAYAGCwkI BwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEE3eEPcA/4Na5IIP/3T/FIQMxIfNzZshIq687qgG 8UbspuE/YSUDdv7r5szYTK6KPTlqN8NAcSfheywbuYD9A4ZeSBWD3/NAVUdrCaRP2IvFyELj xoMvfJccbq45BxzgEspg/bVahNbyuBpLBVjVWwRtFCUEXkyazksSv8pdTMAs9IucChvFmmq3 jJ2vlaz9lYt/lxN246fIVceckPMiUveimngvXZw21VOAhfQ+/sofXF8JCFv2mFcBDoa7eYob s0FLpmqFaeNRHAlzMWgSsP80qx5nWWEvRLdKWi533N2vC/EyunN3HcBwVrXH4hxRBMco3jvM m8VKLKao9wKj82qSivUnkPIwsAGNPdFoPbgghCQiBjBe6A75Z2xHFrzo7t1jg7nQfIyNC7ez MZBJ59sqA9EDMEJPlLNIeJmqslXPjmMFnE7Mby/+335WJYDulsRybN+W5rLT5aMvhC6x6POK z55fMNKrMASCzBJum2Fwjf/VnuGRYkhKCqqZ8gJ3OvmR50tInDV2jZ1DQgc3i550T5JDpToh dPBxZocIhzg+MBSRDXcJmHOx/7nQm3iQ6iLuwmXsRC6f5FbFefk9EjuTKcLMvBsEx+2DEx0E UnmJ4hVg7u1PQ+2Oy+Lh/opK/BDiqlQ8Pz2jiXv5xkECvr/3Sv59hlOCZMOaiLTTjtOIU7Tq 7ut6OL64oAq+zsFNBFXLn5EBEADn1959INH2cwYJv0tsxf5MUCghCj/CA/lc/LMthqQ773ga uB9mN+F1rE9cyyXb6jyOGn+GUjMbnq1o121Vm0+neKHUCBtHyseBfDXHA6m4B3mUTWo13nid 0e4AM71r0DS8+KYh6zvweLX/LL5kQS9GQeT+QNroXcC1NzWbitts6TZ+IrPOwT1hfB4WNC+X 2n4AzDqp3+ILiVST2DT4VBc11Gz6jijpC/KI5Al8ZDhRwG47LUiuQmt3yqrmN63V9wzaPhC+ xbwIsNZlLUvuRnmBPkTJwwrFRZvwu5GPHNndBjVpAfaSTOfppyKBTccu2AXJXWAE1Xjh6GOC 8mlFjZwLxWFqdPHR1n2aPVgoiTLk34LR/bXO+e0GpzFXT7enwyvFFFyAS0Nk1q/7EChPcbRb hJqEBpRNZemxmg55zC3GLvgLKd5A09MOM2BrMea+l0FUR+PuTenh2YmnmLRTro6eZ/qYwWkC u8FFIw4pT0OUDMyLgi+GI1aMpVogTZJ70FgV0pUAlpmrzk/bLbRkF3TwgucpyPtcpmQtTkWS gDS50QG9DR/1As3LLLcNkwJBZzBG6PWbvcOyrwMQUF1nl4SSPV0LLH63+BrrHasfJzxKXzqg rW28CTAE2x8qi7e/6M/+XXhrsMYG+uaViM7n2je3qKe7ofum3s4vq7oFCPsOgwARAQABwsFl BBgBAgAPBQJVy5+RAhsMBQkJZgGAAAoJEE3eEPcA/4NagOsP/jPoIBb/iXVbM+fmSHOjEshl KMwEl/m5iLj3iHnHPVLBUWrXPdS7iQijJA/VLxjnFknhaS60hkUNWexDMxVVP/6lbOrs4bDZ NEWDMktAeqJaFtxackPszlcpRVkAs6Msn9tu8hlvB517pyUgvuD7ZS9gGOMmYwFQDyytpepo YApVV00P0u3AaE0Cj/o71STqGJKZxcVhPaZ+LR+UCBZOyKfEyq+ZN311VpOJZ1IvTExf+S/5 lqnciDtbO3I4Wq0ArLX1gs1q1XlXLaVaA3yVqeC8E7kOchDNinD3hJS4OX0e1gdsx/e6COvy qNg5aL5n0Kl4fcVqM0LdIhsubVs4eiNCa5XMSYpXmVi3HAuFyg9dN+x8thSwI836FoMASwOl C7tHsTjnSGufB+D7F7ZBT61BffNBBIm1KdMxcxqLUVXpBQHHlGkbwI+3Ye+nE6HmZH7IwLwV W+Ajl7oYF+jeKaH4DZFtgLYGLtZ1LDwKPjX7VAsa4Yx7S5+EBAaZGxK510MjIx6SGrZWBrrV TEvdV00F2MnQoeXKzD7O4WFbL55hhyGgfWTHwZ457iN9SgYi1JLPqWkZB0JRXIEtjd4JEQcx +8Umfre0Xt4713VxMygW0PnQt5aSQdMD58jHFxTk092mU+yIHj5LeYgvwSgZN4airXk5yRXl SE+xAvmumFBY Organization: Red Hat GmbH Message-ID: <14a03703-a0af-1120-dabd-69bfba670f13@redhat.com> Date: Tue, 4 Jun 2019 10:11:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <3bec7cf0-9be1-ea6f-7dbc-cbf95fd08293@linux.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 04 Jun 2019 08:11:31 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v1 2/2] s390x/tcg: Store only the necessary amount of doublewords for STFLE X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , Ilya Leoshkevich , Andreas Krebbel , Cornelia Huck , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 03.06.19 16:39, Stefan Liebler wrote: > On 6/3/19 12:45 PM, David Hildenbrand wrote: >> On 03.06.19 12:38, Stefan Liebler wrote: >>> On 5/31/19 4:56 PM, David Hildenbrand wrote: >>>> The PoP (z14, 7-382) says: >>>> Doublewords to the right of the doubleword in which the >>>> highest-numbered facility bit is assigned for a model >>>> may or may not be stored. >>>> >>>> However, stack protection in certain binaries can't deal with that. >>>> "gzip" example code: >>>> >>>> f1b4: a7 08 00 03 lhi %r0,3 >>>> f1b8: b2 b0 f0 a0 stfle 160(%r15) >>>> f1bc: e3 20 f0 b2 00 90 llgc %r2,178(%r15) >>>> f1c2: c0 2b 00 00 00 01 nilf %r2,1 >>>> f1c8: b2 4f 00 10 ear %r1,%a0 >>>> f1cc: b9 14 00 22 lgfr %r2,%r2 >>>> f1d0: eb 11 00 20 00 0d sllg %r1,%r1,32 >>>> f1d6: b2 4f 00 11 ear %r1,%a1 >>>> f1da: d5 07 f0 b8 10 28 clc 184(8,%r15),40(%r1) >>>> f1e0: a7 74 00 06 jne f1ec >>>> f1e4: eb ef f1 30 00 04 lmg %r14,%r15,304(%r15) >>>> f1ea: 07 fe br %r14 >>>> f1ec: c0 e5 ff ff 9d 6e brasl %r14,2cc8 <__stack_chk_fail@plt> >>>> >>>> In QEMU, we currently have: >>>> max_bytes = 24 >>>> the code asks for (3 + 1) doublewords == 32 bytes. >>>> >>>> If we write 32 bytes instead of only 24, and return "2 + 1" doublewords >>>> ("one less than the number of doulewords needed to contain all of the >>>> facility bits"), the example code detects a stack corruption. >>>> >>>> In my opinion, the code is wrong. However, it seems to work fine on >>>> real machines. So let's limit storing to the minimum of the requested >>>> and the maximum doublewords. >>> Hi David, >>> >>> Thanks for catching this. I've reported the "gzip" example to Ilya and >>> indeed, r0 is setup too large. He will fix it in gzip. >>> >>> You've mentioned, that this is detected in certain binaries. >>> Can you please share those occurrences. >> >> Hi Stafan, >> >> thanks for your reply. >> >> I didn't track all occurrences, it *could* be that it was only gzip in >> the background making other processes fail. >> >> For example, the systemd "vitual console setup" unit failed, too, which >> was fixed by this change. > At least "objdump -d /usr/lib/systemd/systemd-vconsole-setup" does not > contain the stfle instruction, but "ldd > /usr/lib/systemd/systemd-vconsole-setup" is showing libz.so which could > also contain Ilya's patches with the stfle instruction (I assume there > is the same bug as in gzip). But I have no idea if libz is really called. >> >> I also remember, seeing segfaults in rpmbuild, for example. They only >> "changed" with this fix - I m still chasing different errors. :) > The same applies for rpmbuild. >> >> You mentioned "He will fix it in gzip", so I assume this is a gzip issue >> and not a gcc/glibc/whatever toolchain issue? >> > Yes, this is a gzip bug. r0 was initialized with: > (sizeof(array-on-stack) / 8) > instead of: > (sizeof(array-on-stack) / 8) - 1 > > Ilya will fix it in gzip and zlib. > @Ilya: Please correct me if I'm wrong. > Makes sense, thanks for the explanation! -- Thanks, David / dhildenb