Bug#882255: libc6-amd64: Multilib causes catastrophic system failure during upgrade to libc 2.25
control: tag -1 - pending
On 2017-12-02 03:34, Mikulas Patocka wrote:
>
>
> On Sun, 26 Nov 2017, Aurelien Jarno wrote:
>
> > > > You mean that even now running 'ldconfig' followed by 'ldd /bin/true'
> > > > will give you
> > > > libc.so.6 => /lib64/libc.so.6
> > > > instead of
> > > > libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6
> > > > ?
> > >
> > > Yes.
> > > # ldd /bin/true
> > > linux-vdso.so.1 (0x00007ffc62b5a000)
> > > libc.so.6 => /lib64/libc.so.6 (0x00007fd870377000)
> > > /lib64/ld-linux-x86-64.so.2 (0x00007fd870921000)
> > >
> > > If I use the --inhibit-cache flag, it points to the correct location:
> > > # /lib64/ld-linux-x86-64.so.2 --list --inhibit-cache /bin/true
> > > linux-vdso.so.1 (0x00007ffd566e4000)
> > > libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f73026c8000)
> > > /lib64/ld-linux-x86-64.so.2 (0x00007f7302c73000)
> > >
> > > Without --inhibit-cache, it points to /lib64/libc.so.6
> > > # /lib64/ld-linux-x86-64.so.2 --list /bin/true
> > > linux-vdso.so.1 (0x00007ffd5ad10000)
> > > libc.so.6 => /lib64/libc.so.6 (0x00007fc566092000)
> > > /lib64/ld-linux-x86-64.so.2 (0x00007fc56663c000)
> >
> > I am still unable to reproduce this problem. On my system
> > lib/x86_64-linux-gnu/ is preferred over lib64. ldconfig uses glob to to
> > interpret the "*.conf" in /etc/ld.so.conf, so the files are sorted
> > alphabetically and thus the zz_amd64-biarch-compat.conf should appear
> > last.
> >
> > It would be interesting to check at the order in the cache, using
> > "ldconfig -p | grep libc.so". Could you please provide that output?
> >
> > Thanks,
> > Aurelien
>
> # ldconfig -p | grep libc.so
> libc.so.6 (libc6,x32, ABI OS: Linux 3.4.0) => /lib/x86_64-linux-gnux32/libc.so.6
> libc.so.6 (libc6,x86-64, ABI OS: Linux 3.2.0) => /lib64/libc.so.6
> libc.so.6 (libc6,x86-64, ABI OS: Linux 2.6.32) => /lib/x86_64-linux-gnu/libc.so.6
> libc.so.6 (libc6, ABI OS: Linux 3.2.0) => /lib32/libc.so.6
> libc.so.6 (libc6, ABI OS: Linux 2.6.32) => /lib/i386-linux-gnu/libc.so.6
>
> The problem is caused by the "ABI OS" field - the libraries in /lib64 have
> higher field than the libraries in /lib/x86_64-linux-gnu/
Thanks for the details. I did all my tests with libc6:amd64 and
libc6-amd64:i386, and the problem is at the end specific to
libc6-amd64:x32. On the other hand i was able to reproduce the issue by
changing locales, so that's at least one more possibility of this bug to
get detected.
> If I comment out this piece of code in the function compare in the file
> glibc/elf/cache.c, the problem goes away and the linker will prefer
> libraries in /lib/x86_64-linux-gnu/ and /lib/i386-linux-gnu/.
>
> /*
> if (e2->osversion > e1->osversion)
> return 1;
> if (e2->osversion < e1->osversion)
> return -1;
> */
Some libraries other than libc.so.6 might use this mechanism, so we
can't really disable it. On the other hand we can ensure that all libc
for a given architecture and version are built for the same kernel
version.
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net
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