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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id BCC8CC433F5 for ; Sun, 26 Dec 2021 12:32:07 +0000 (UTC) Received: from localhost ([::1]:37120 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n1Sh4-0000WG-C0 for qemu-devel@archiver.kernel.org; Sun, 26 Dec 2021 07:32:06 -0500 Received: from eggs.gnu.org ([209.51.188.92]:58562) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n1Sfz-0008E2-R2 for qemu-devel@nongnu.org; Sun, 26 Dec 2021 07:30:59 -0500 Received: from smtp-relay-services-0.canonical.com ([185.125.188.250]:40808) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n1Sfw-0007rI-Mv for qemu-devel@nongnu.org; Sun, 26 Dec 2021 07:30:59 -0500 Received: from loganberry.canonical.com (loganberry.canonical.com [91.189.90.37]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp-relay-services-0.canonical.com (Postfix) with ESMTPSA id 751923F323 for ; Sun, 26 Dec 2021 12:30:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=launchpad.net; s=20210803; t=1640521846; bh=O2KiekUBOHZrymOvPcyXOB+BcNGJxn0N+mPxXWUBWJw=; h=MIME-Version:Content-Type:Date:From:To:Reply-To:References: Message-Id:Subject; b=CHUqRoHkzZPBYzvh21t02Fd93URDiJ/ZcfjqTUnd0Zm06I3QtZYU6TYFlTSilJulD JU49C6BJqndAGO5JGcpm19vy+SyxfFXycqthveum/aKGBg6+txNpp7eRO6/Xabb0Dp unhRGRlwKRUNp0al45Fzj4OfCEh8u3yDeDBszzMblo4ms9i9nAkS7k4gaorjVVpZZ6 hWAfA9uJLYbK5U7L95IYLM1b05zllU4b66nl93GxVVe5DFb5PJkVjlvDuTVngitLGP cF/RYqEX59AmeSEaXbgTN5tBQf2N7n9MiebVK8l4evfM0gNGMTyGohkT1HRKF1tDaE yTJL+BM+kA6RA== Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 618602E81A4 for ; Sun, 26 Dec 2021 12:30:44 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Sun, 26 Dec 2021 12:21:37 -0000 From: frank <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=None; X-Launchpad-Bug: distribution=ubuntu; distroseries=focal; sourcepackage=qemu; component=main; status=Fix Committed; importance=Medium; assignee=christian.ehrhardt@canonical.com; X-Launchpad-Bug-Tags: arm linux-user qemu-20.10 server-next verification-done verification-done-focal X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: brian-murray doko frankwu gerard-f-vidal-4 hertzog janitor komainu8 laurent-vivier paelzer peterogden pmaydell racb rth sebunger44 X-Launchpad-Bug-Reporter: =?utf-8?q?Rapha=C3=ABl_Hertzog_=28hertzog=29?= X-Launchpad-Bug-Modifier: frank (frankwu) References: <151859702399.9461.6832978283203997178.malonedeb@chaenomeles.canonical.com> Message-Id: <164052129794.28891.4336336412190075222.malone@gac.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="adb364d6a74a28e7b95d51cd30446ec16160de6c"; Instance="production" X-Launchpad-Hash: eaeb2a76bd0b439ac6f1fc1491c4bede860148f0 Received-SPF: pass client-ip=185.125.188.250; envelope-from=noreply@launchpad.net; helo=smtp-relay-services-0.canonical.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 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" i can confirm that focal-proposed package fixes problems for arm64 and armhf on hostarch amd64 note: tried ppa listed here which fixes for arm64 but breaks armhf: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1928075/comments/15 steps for installing proposed Package: cat </etc/apt/sources.list.d/ubuntu-$(lsb_release -cs)-proposed.list # Enable Ubuntu proposed archive deb http://archive.ubuntu.com/ubuntu/ $(lsb_release -cs)-proposed restricte= d main multiverse universe EOF cat </etc/apt/preferences.d/proposed-updates # Configure apt to allow selective installs of packages from proposed Package: * Pin: release a=3D$(lsb_release -cs)-proposed Pin-Priority: 400 EOF apt update apt install qemu-user-static/focal-proposed then build 2 bullseye-chroot (arm64 and armhf) including secondstage and no crash happens --=20 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: Fix Committed Bug description: [Impact] =C2=A0* The current space reserved can be too small and we can end up =C2=A0=C2=A0=C2=A0with no space at all for BRK. It can happen to any case= , but is =C2=A0=C2=A0=C2=A0much more likely with the now common PIE binaries. =C2=A0* Backport the upstream fix which reserves a bit more space while l= oading =C2=A0=C2=A0=C2=A0and giving it back after interpreter and stack is loade= d. [Test Plan] =C2=A0* 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: =C2=A0libc-bin E: Sub-process /usr/bin/dpkg returned an error code (1) =20 Second test from bug 1928075 $ sudo qemu-debootstrap --arch=3Darm64 bullseye bullseye-arm64 http://ftp.debian.org/debian In the bad case this is failing like W: Failure trying to run: /sbin/ldconfig W: See //debootstrap/debootstrap.log for detail And in that log file you'll see the segfault $ tail -n 2 bullseye-arm64/debootstrap/debootstrap.log qemu: uncaught target signal 11 (Segmentation fault) - core dumped Segmentation fault (core dumped) [Where problems could occur] =C2=A0* Regressions would be around use-cases of linux-user that is =C2=A0=C2=A0=C2=A0emulation not of a system but of binaries. =C2=A0=C2=A0=C2=A0Commonly uses for cross-tests and cross-builds so that = is the =C2=A0=C2=A0=C2=A0space to watch for regressions [Other Info] =C2=A0* 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