From: "Christian Ehrhardt " <1749393@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1749393] Re: sbrk() not working under qemu-user with a PIE-compiled binary?
Date: Fri, 01 May 2020 06:47:12 -0000 [thread overview]
Message-ID: <158831563276.13979.12202053518555221631.malone@gac.canonical.com> (raw)
In-Reply-To: 151859702399.9461.6832978283203997178.malonedeb@chaenomeles.canonical.com
Will be merged in 20.10 with qemu >=5.0 where this came upstream.
** Tags added: qemu-20.10
** Changed in: qemu (Ubuntu)
Status: Confirmed => Triaged
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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:
Triaged
Bug description:
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 allocated)
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 suggested that the issue might be in qemu-user so I'm opening a ticket here. Here'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/bash/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 kernel and now the problem only appears when run under qemu-user:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1518483
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next prev parent reply other threads:[~2020-05-01 6:57 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-14 8:30 [Qemu-devel] [Bug 1749393] [NEW] sbrk() not working under qemu-user with a PIE-compiled binary? Raphaël Hertzog
2018-02-14 15:46 ` [Qemu-devel] [Bug 1749393] " Gérard Vidal
2018-03-01 19:15 ` Peter Ogden
2018-03-15 11:39 ` Peter Maydell
2018-03-15 15:27 ` Matthias Klose
2018-03-15 16:17 ` Peter Maydell
2018-03-15 17:56 ` Peter Ogden
2018-03-22 21:45 ` Launchpad Bug Tracker
2018-04-04 16:16 ` Matthias Klose
2020-01-17 23:52 ` Richard Henderson
2020-03-10 9:07 ` Laurent Vivier
2020-04-30 13:34 ` Laurent Vivier
2020-05-01 6:47 ` Christian Ehrhardt [this message]
2020-06-17 7:52 ` Christian Ehrhardt
2020-08-01 5:05 ` Launchpad Bug Tracker
2021-04-19 23:03 ` Robie Basak
2021-04-26 9:12 ` Launchpad Bug Tracker
2021-04-26 9:17 ` Christian Ehrhardt
2021-04-26 9:30 ` Christian Ehrhardt
2021-05-21 0:53 ` Yasuhiro Horimoto
2021-09-17 4:33 ` Sebastian Unger
2021-09-20 9:58 ` Christian Ehrhardt
2021-11-30 8:44 ` Christian Ehrhardt
2021-11-30 9:20 ` Christian Ehrhardt
2021-11-30 9:25 ` Christian Ehrhardt
2021-11-30 10:10 ` Christian Ehrhardt
2021-11-30 19:28 ` Brian Murray
2021-12-01 7:46 ` Christian Ehrhardt
2021-12-16 7:53 ` Christian Ehrhardt
2021-12-26 12:21 ` frank
2022-01-03 11:42 ` Christian Ehrhardt
2022-01-04 17:38 ` Launchpad Bug Tracker
2022-01-04 17:39 ` [Bug 1749393] Update Released Brian Murray
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