Bug#882255: libc6-amd64: Multilib causes catastrophic system failure during upgrade to libc 2.25
On Tue, 21 Nov 2017, Aurelien Jarno wrote:
> On 2017-11-21 00:12, Mikulas Patocka wrote:
> >
> >
> > On Mon, 20 Nov 2017, Aurelien Jarno wrote:
> >
> > > On 2017-11-20 19:13, Mikulas Patocka wrote:
> > > > Package: libc6-amd64
> > > > Version: 2.25-1
> > > > Severity: critical
> > > > Justification: breaks the whole system
> > > >
> > > > Dear Maintainer,
> > > >
> > > > *** Reporter, please consider answering these questions, where appropriate ***
> > > >
> > > > * What led up to the situation?
> > > >
> > > > I have a x86-64 system with i386 and x32 foreign architectures (because I
> > > > need to develop software for i386 and x32 architectures).
> > > >
> > > > * What exactly did you do (or not do) that was effective (or
> > > > ineffective)?
> > > >
> > > > I ran apt update and apt upgrade. Apt tried to upgrade to libc-2.25.
> > > >
> > > > * What was the outcome of this action?
> > > >
> > > > Halfway through apt upgrade it failed and I ended up with unusable system where
> > > > large number of binaries were segfauting on startup without doign anything.
> > > >
> > > > * What outcome did you expect instead?
> > > >
> > > > The upgrade to libc-2.25 should work.
> > > >
> > > >
> > > > The reason for the catastrophic failure is this:
> > > >
> > > > There is package libc6-amd64:i386 and libc6-amd64:x32 (which provide
> > >
> > > I guess you mean you have installed one of the two, not both.
> > >
> > > > x86-64 libc in /lib64/). This package is not technically needed (because
> > > > x86-64 libc is already installed in /lib/x86_64-linux-gnu/), but it is
> > > > installed nonetheless because of some dependencies.
> > >
> > > Just to be clear, as said in my other email, this *is* technically
> > > needed as gcc-multilib is not able to make use of the libc in
> > > /lib/x86_64-linux-gnu.
> > >
> > > > apt makes sure that all libc packages are upgraded at once to the same
> > > > version. However, during the upgrade process, the package
> > > > libc6-amd64 is upgraded before libc6:amd64. So, during the upgrade, we
> > > > temporarily have two libcs with different versions on the system, and this
> > > > mismatch makes most of the x86-64 binaries crash. Due to the crashes, the
> > > > upgrade doesn't proceed and it doesn't install the correct libc version in
> > > > /lib/x86_64-linux-gnu/.
> > > >
> > > > The result is unusable system.
> > >
> > > I have done some tests, and while I confirm that libc6-i386:amd64 is
> >
> > The problem is with libc6-amd64:i386 or libc6-amd64:x32.
> > Not libc6-i386:amd64.
>
> Yes, sorry about that, I really did the test with libc6-amd64:i386, but
> mixed it when typing the mail.
>
> > I.e. use amd64 Debian Sid base installation, add foreign architectures
> > i386 and x32 and use this /etc/apt/sources.list:
> >
> > deb [ arch=i386,amd64 ] http://ftp.cz.debian.org/debian/ sid main contrib non-free
> > deb [ arch=x32 ] http://ftp.de.debian.org/debian-ports/ unreleased main
> > deb [ arch=x32 ] http://ftp.de.debian.org/debian-ports/ unstable main
> >
> > > unpacked much before libc6:amd64, it doesn't cause any issue here.
> > > Indeed the search path in ld.so is to give higher priority to
> > > /lib/x86_64-linux-gnu/ over /lib64. I have even been able to install
> > > libc6:amd64 in version 2.24 (using force-all), while keeping
> > > libc6-amd64:i386 in version 2.25.
> > >
> > > The only way to change the priority of the two path is using a
> > > non-standard ld.so.conf. Have you made any change to /etc/ld.so.conf or
> > > /etc/ld.so.conf.d/*? Maybe you can share the content of this file and
> > > this directory.
> >
> > On my system, there's a file /etc/ld.so.conf.d/zz_amd64-biarch-compat.conf
> > containing:
> >
> > # Legacy biarch compatibility support
> > /lib64
> > /usr/lib64
> >
> > and /etc/ld.so.conf.d/zz_i386-biarch-compat.conf containing:
> >
> > # Legacy biarch compatibility support
> > /lib32
> > /usr/lib32
> >
> > These files are created by the packages libc6-i386:x32 and
> > libc6-amd64:x32. They cause that /lib64 is preferred to
> > /lib/x86_64-linux-gnu/. If I delete these files and run ldconfig, the
> > linker will prefer /lib/x86_64-linux-gnu/.
>
> Those files are installed with the zz_ prefix to make sure they are
> included last, and therefore after x86_64-linux-gnu.conf. It seems to
> be missing on your system and is probably the root of your problem. This
> file is installed by libc6:amd64.
>
> Aurelien
I have /etc/ld.so.conf.d/x86_64-linux-gnu.conf, it contains
# Multiarch support
/lib/x86_64-linux-gnu
/usr/lib/x86_64-linux-gnu
But nonetheless, the linker prefers libc from /lib64.
I have these files in /etc/ld.so.conf.d:
i386-linux-gnu.conf:# Multiarch support
i386-linux-gnu.conf:/lib/i386-linux-gnu
i386-linux-gnu.conf:/usr/lib/i386-linux-gnu
i386-linux-gnu.conf:/lib/i686-linux-gnu
i386-linux-gnu.conf:/usr/lib/i686-linux-gnu
libc.conf:# libc default configuration
libc.conf:/usr/local/lib
x86_64-linux-gnu.conf:# Multiarch support
x86_64-linux-gnu.conf:/lib/x86_64-linux-gnu
x86_64-linux-gnu.conf:/usr/lib/x86_64-linux-gnu
x86_64-linux-gnux32.conf:# Multiarch support
x86_64-linux-gnux32.conf:/lib/x86_64-linux-gnux32
x86_64-linux-gnux32.conf:/usr/lib/x86_64-linux-gnux32
zz_amd64-biarch-compat.conf:# Legacy biarch compatibility support
zz_amd64-biarch-compat.conf:/lib64
zz_amd64-biarch-compat.conf:/usr/lib64
zz_i386-biarch-compat.conf:# Legacy biarch compatibility support
zz_i386-biarch-compat.conf:/lib32
zz_i386-biarch-compat.conf:/usr/lib32
/etc/ld.so.conf contains just one line:
include /etc/ld.so.conf.d/*.conf
Mikulas
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