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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 E4005C433B4 for ; Mon, 26 Apr 2021 09:32:26 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CBA4B61075 for ; Mon, 26 Apr 2021 09:32:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CBA4B61075 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43298 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1laxbM-0005Wc-NU for qemu-devel@archiver.kernel.org; Mon, 26 Apr 2021 05:32:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:40268) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1laxa5-0004v8-WF for qemu-devel@nongnu.org; Mon, 26 Apr 2021 05:31:07 -0400 Received: from indium.canonical.com ([91.189.90.7]:51870) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1laxZz-0007zt-Rg for qemu-devel@nongnu.org; Mon, 26 Apr 2021 05:31:03 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1laxZx-0007mE-0C for ; Mon, 26 Apr 2021 09:30:57 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 68D592E817D for ; Mon, 26 Apr 2021 09:30:56 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Mon, 26 Apr 2021 09:17:40 -0000 From: =?utf-8?q?Christian_Ehrhardt_=EE=83=BF?= <1749393@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=Fix Released; importance=Undecided; assignee=None; X-Launchpad-Bug: distribution=ubuntu; sourcepackage=qemu; component=main; status=Fix Released; importance=Undecided; assignee=christian.ehrhardt@canonical.com; X-Launchpad-Bug: distribution=ubuntu; distroseries=focal; sourcepackage=qemu; component=main; status=Triaged; importance=Medium; assignee=None; X-Launchpad-Bug-Tags: arm linux-user qemu-20.10 X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: doko gerard-f-vidal-4 hertzog janitor laurent-vivier paelzer peterogden pmaydell racb rth X-Launchpad-Bug-Reporter: =?utf-8?q?Rapha=C3=ABl_Hertzog_=28hertzog=29?= X-Launchpad-Bug-Modifier: =?utf-8?q?Christian_Ehrhardt_=EE=83=BF_=28paelzer?= =?utf-8?q?=29?= References: <151859702399.9461.6832978283203997178.malonedeb@chaenomeles.canonical.com> Message-Id: <161942866119.11530.14313514059610342699.launchpad@wampee.canonical.com> Subject: [Bug 1749393] Re: sbrk() not working under qemu-user with a PIE-compiled binary? X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="f9f562f07f129de414c16be22a405ff0964e0018"; Instance="production" X-Launchpad-Hash: c9bd862f9a6764fc517a60d69068c18efc99d354 Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-Spam_score_int: -66 X-Spam_score: -6.7 X-Spam_bar: ------ X-Spam_report: (-6.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.25, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1749393 <1749393@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" ** Description changed: + [Impact] + = + * The current space reserved can be too small and we can end up + with no space at all for BRK. It can happen to any case, but is + much more likely with the now common PIE binaries. + = + * Backport the upstream fix which reserves a bit more space while loading + and giving it back after interpreter and stack is loaded. + = + [Test Plan] + = + * On x86 run: + sudo apt install -y qemu-user-static docker.io + sudo docker run --rm arm64v8/debian:bullseye bash -c 'apt update && apt i= nstall -y wget' + ... + Running hooks in /etc/ca-certificates/update.d... + done. + Errors were encountered while processing: + libc-bin + E: Sub-process /usr/bin/dpkg returned an error code (1) + = + = + [Where problems could occur] + = + * Regressions would be around use-cases of linux-user that is + emulation not of a system but of binaries. + Commonly uses for cross-tests and cross-builds so that is the + space to watch for regressions + = + [Other Info] + = + * n/a + = + = + --- + = In Debian unstable, we recently switched bash to be a PIE-compiled binary (for hardening). Unfortunately this resulted in bash being broken when run under qemu-user (for all target architectures, host being amd64 for me). = $ sudo chroot /srv/chroots/sid-i386/ qemu-i386-static /bin/bash bash: xmalloc: .././shell.c:1709: cannot allocate 10 bytes (0 bytes alloc= ated) = bash has its own malloc implementation based on sbrk(): https://git.savannah.gnu.org/cgit/bash.git/tree/lib/malloc/malloc.c = When we disable this internal implementation and rely on glibc's malloc, then everything is fine. But it might be that glibc has a fallback when sbrk() is not working properly and it might hide the underlying problem in qemu-user. = This issue has also been reported to the bash upstream author and he sugg= ested that the issue might be in qemu-user so I'm opening a ticket here. He= re's the discussion with the bash upstream author: https://lists.gnu.org/archive/html/bug-bash/2018-02/threads.html#00080 = You can find the problematic bash binary in that .deb file: http://snapshot.debian.org/archive/debian/20180206T154716Z/pool/main/b/ba= sh/bash_4.4.18-1_i386.deb = The version of qemu I have been using is 2.11 (Debian package qemu-user- static version 1:2.11+dfsg-1) but I have had reports that the problem is reproducible with older versions (back to 2.8 at least). = Here are the related Debian bug reports: https://bugs.debian.org/889869 https://bugs.debian.org/865599 = It's worth noting that bash used to have this problem (when compiled as a= PIE binary) even when run directly but then something got fixed in the ker= nel and now the problem only appears when run under qemu-user: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1518483 -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1749393 Title: sbrk() not working under qemu-user with a PIE-compiled binary? Status in QEMU: Fix Released Status in qemu package in Ubuntu: Fix Released Status in qemu source package in Focal: Triaged Bug description: [Impact] * The current space reserved can be too small and we can end up with no space at all for BRK. It can happen to any case, but is much more likely with the now common PIE binaries. * Backport the upstream fix which reserves a bit more space while loading and giving it back after interpreter and stack is loaded. [Test Plan] * On x86 run: sudo apt install -y qemu-user-static docker.io sudo docker run --rm arm64v8/debian:bullseye bash -c 'apt update && apt i= nstall -y wget' ... Running hooks in /etc/ca-certificates/update.d... done. Errors were encountered while processing: libc-bin E: Sub-process /usr/bin/dpkg returned an error code (1) = [Where problems could occur] * Regressions would be around use-cases of linux-user that is emulation not of a system but of binaries. Commonly uses for cross-tests and cross-builds so that is the space to watch for regressions [Other Info] = * n/a --- In Debian unstable, we recently switched bash to be a PIE-compiled binary (for hardening). Unfortunately this resulted in bash being broken when run under qemu-user (for all target architectures, host being amd64 for me). $ sudo chroot /srv/chroots/sid-i386/ qemu-i386-static /bin/bash bash: xmalloc: .././shell.c:1709: cannot allocate 10 bytes (0 bytes alloc= ated) bash has its own malloc implementation based on sbrk(): https://git.savannah.gnu.org/cgit/bash.git/tree/lib/malloc/malloc.c When we disable this internal implementation and rely on glibc's malloc, then everything is fine. But it might be that glibc has a fallback when sbrk() is not working properly and it might hide the underlying problem in qemu-user. This issue has also been reported to the bash upstream author and he sugg= ested that the issue might be in qemu-user so I'm opening a ticket here. He= re's the discussion with the bash upstream author: https://lists.gnu.org/archive/html/bug-bash/2018-02/threads.html#00080 You can find the problematic bash binary in that .deb file: http://snapshot.debian.org/archive/debian/20180206T154716Z/pool/main/b/ba= sh/bash_4.4.18-1_i386.deb The version of qemu I have been using is 2.11 (Debian package qemu- user-static version 1:2.11+dfsg-1) but I have had reports that the problem is reproducible with older versions (back to 2.8 at least). Here are the related Debian bug reports: https://bugs.debian.org/889869 https://bugs.debian.org/865599 It's worth noting that bash used to have this problem (when compiled as a= PIE binary) even when run directly but then something got fixed in the ker= nel and now the problem only appears when run under qemu-user: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1518483 To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1749393/+subscriptions