[Pkg-libvirt-maintainers] Bug#883785: libvirtd 3.10 segfault when starting a VM

[Pascal Obry]

Package: libvirt
Version: 3.10
Severity: grave

With libvirt version 3.10 I cannot start a VM. Reverting to 3.0
(Debian/stable) all is fine. This was initially found in GNOME-Boxes
but I have been able to reproduce on the command line using virsh.

Note also that I had the same issue with 3.9.

On one console:

$ LIBVIRT_DEBUG=1 gdb /usr/sbin/libvirtd

On a second console, I tried to start the VM:

$ virsh start boxes-winxp

Then I got this exception from libvirtd:

Thread 5 "libvirtd" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7febad4a5700 (LWP 7867)]
0x00007feb94b109c8 in virStorageFileReportBrokenChain ()
   from /usr/lib/libvirt/connection-driver/libvirt_driver_storage.so
(gdb) bt
#0  0x00007feb94b109c8 in virStorageFileReportBrokenChain ()
   from /usr/lib/libvirt/connection-driver/libvirt_driver_storage.so
#1  0x00007feb7d266da3 in qemuDomainDetermineDiskChain ()
   from /usr/lib/libvirt/connection-driver/libvirt_driver_qemu.so
#2  0x00007feb7d28eec2 in qemuProcessPrepareHost ()
   from /usr/lib/libvirt/connection-driver/libvirt_driver_qemu.so
#3  0x00007feb7d294b71 in qemuProcessStart ()
   from /usr/lib/libvirt/connection-driver/libvirt_driver_qemu.so
#4  0x00007feb7d2f5201 in ?? ()
   from /usr/lib/libvirt/connection-driver/libvirt_driver_qemu.so
#5  0x00007feb7d2f58e6 in ?? ()
   from /usr/lib/libvirt/connection-driver/libvirt_driver_qemu.so
#6  0x00007febb9e5e077 in virDomainCreate (domain=0x7feb980008c0)
    at ../../../src/libvirt-domain.c:6531
#7  0x000056190ba2ed9c in ?? ()
#8  0x00007febb9ec697c in virNetServerProgramDispatchCall (msg=0x56190d9e7590, 
    client=0x56190d9e6fb0, server=0x56190d9d00f0, prog=0x56190d9e4f40)
    at ../../../src/rpc/virnetserverprogram.c:437
#9  virNetServerProgramDispatch (prog=0x56190d9e4f40, server=0x56190d9d00f0, 
    client=0x56190d9e6fb0, msg=0x56190d9e7590)
    at ../../../src/rpc/virnetserverprogram.c:307
#10 0x000056190ba3e988 in ?? ()
#11 0x00007febb9da1c01 in virThreadPoolWorker (
    opaque=opaque at entry=0x56190d9ce9f0)
    at ../../../src/util/virthreadpool.c:167
#12 0x00007febb9da0f78 in virThreadHelper (data=<optimized out>)
    at ../../../src/util/virthread.c:206
#13 0x00007febb68b0519 in start_thread (arg=0x7febad4a5700)
    at pthread_create.c:456
#14 0x00007febb65f2a5f in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97
(gdb) 

I noticed that running with 3.0 I had a message saying that /dev/sr0 is
not accessible. And indeed I do not have a CDROM on this machine. The
.xml were migrated from a machine with a CDROM to this new one.

Removing:

    <disk type='block' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source dev='/dev/sr0' startupPolicy='optional'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
    </disk>

Seems to fix the issue. Yet, libvirt should not crash on this. And the
backtrace makes sense with this fix BTW.

Please let me know if you need additional information.

Thanks,

-- 
  Pascal Obry /  Magny Les Hameaux (78)

  The best way to travel is by means of imagination

  http://www.obry.net

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