Package: libc6
Version: 2.24-11+deb9u3
Severity: normal

Dear Maintainer,

When I use 'xl create' or 'xl destroy' to manage Xen domUs, xl segfaults

(gdb) run create /etc/xen/domU.cfg
Starting program: /usr/lib/xen-4.8/bin/xl create /etc/xen/domU.cfg
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/".
Parsing config from /etc/xen/domU.cfg
[New Thread 0x7ffff7ff4700 (LWP 3311)]

Thread 2 "xl" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff7ff4700 (LWP 3311)]
0x00007ffff7de2ff5 in _dl_lookup_symbol_x (undef_name=0x7ffff5478c63 
"_Unwind_Find_FDE", undef_map=0x555555788310, 
    ref=ref@entry=0x7ffff7ff2128, symbol_scope=0x555555788668, 
version=0x555555788a50, type_class=type_class@entry=1, flags=5, 
    skip_map=0x0) at dl-lookup.c:833

Despite the segfault, it seems that the domU is running fine, which
might explain why this wasn't reported yet AFAIK.

In the exact same software environment, I cannot reproduce this on
pre-Skylake CPUs.

I could confirm that:
- upgrading glibc to 2.26-5 fixes the problem.
- 2.26-4 is still affected.

I looked at the changes between 2.26-4 and 2.26-5.

My initial guess was that this was BZ#22715 due to the link with
AVX-512. But backporting the fix (which is already in
release/2.24/master but not in the stretch package) did not solve the

However, backporting the fix for BZ#22636 fixed the issue (specifically
I backported
, from the release/2.25/master branch).

Could you please backport this fix to the stretch package?



-- System Information:
Debian Release: 9.4
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.9.0-6-amd64 (SMP w/64 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8) (ignored: LC_ALL 
set to en_US.UTF-8), LANGUAGE=en_US:en (charmap=UTF-8) (ignored: LC_ALL set to 
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages libc6 depends on:
ii  libgcc1  1:6.3.0-18+deb9u1

libc6 recommends no packages.

Versions of packages libc6 suggests:
ii  debconf [debconf-2.0]  1.5.61
pn  glibc-doc              <none>
ii  libc-l10n              2.24-11+deb9u3
ii  locales                2.24-11+deb9u3

-- debconf information:
  glibc/upgrade: true
  libraries/restart-without-asking: false

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