Patch applied, installed and rebooted.  Guest VM comes up now.
Thank you!

libvirt-daemon-system:
  Installed: 6.0.0-0ubuntu8.13+lp1943481v20210914b2
  Candidate: 6.0.0-0ubuntu8.13+lp1943481v20210914b2
  Version table:
 *** 6.0.0-0ubuntu8.13+lp1943481v20210914b2 500
        500 http://ppa.launchpad.net/mruffell/lp1943481-test/ubuntu
focal/main amd64 Packages
        100 /var/lib/dpkg/status
     6.0.0-0ubuntu8.13 500
        500 http://us.archive.ubuntu.com/ubuntu focal-updates/main amd64
Packages
     6.0.0-0ubuntu8.3 500
        500 http://us.archive.ubuntu.com/ubuntu focal-security/main amd64
Packages
     6.0.0-0ubuntu8 500
        500 http://us.archive.ubuntu.com/ubuntu focal/main amd64 Packages


On Mon, Sep 13, 2021 at 8:05 PM Matthew Ruffell <email address hidden>
wrote:

> Test packages are now available in:
>
> https://launchpad.net/~mruffell/+archive/ubuntu/lp1943481-test
>
> Please note these test packages are NOT SUPPORTED by Canonical, and are
> for TEST PURPOSES ONLY. ONLY install in a dedicated test environment.
>
> Instructions to Install (on a Focal system):
> 1) sudo add-apt-repository ppa:mruffell/lp1943481-test
> 2) sudo apt update
> 3) sudo apt install libvirt-daemon-system libvirt-clients
> 4) sudo reboot
> 5) sudo apt-cache policy libvirt-daemon-system
> Installed: 6.0.0-0ubuntu8.13+lp1943481v20210914b2
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1943481
>
> Title:
>   libvirtd crashes when creating network interface pools in
>   6.0.0-0ubuntu8.13
>
> Status in libvirt package in Ubuntu:
>   New
> Status in libvirt source package in Focal:
>   In Progress
>
> Bug description:
>   The latest libvirtd (6.0.0-0ubuntu8.13) crashes when trying to bring
>   up network pools with the stacktrace below.  I tracked down the
>   problem to the newly added patch (lp-1892132-Add-phys_port_name-
>   support-on-virPCIGetNetName.patch).  Assigning *netname =
>   firstEntryName; ends up in memory corruption.  Looking at the
>   mainline, I changed it to the following:
>
>   *netname = g_steal_pointer(&firstEntryName);
>
>   or you can just do
>
>   firstEntryName = NULL;
>
>   Both will solve the problem.
>
>
>   #0  __GI_raise (sig=sig@entry=6) at
> ../sysdeps/unix/sysv/linux/raise.c:50
>   #1  0x00007f40e5d1c859 in __GI_abort () at abort.c:79
>   #2  0x00007f40e5d873ee in __libc_message (action=action@entry=do_abort,
> fmt=fmt@entry=0x7f40e5eb1285 "%s\n") at ../sysdeps/posix/libc_fatal.c:155
>   #3  0x00007f40e5d8f47c in malloc_printerr (str=str@entry=0x7f40e5eb35d0
> "free(): double free detected in tcache 2") at malloc.c:5347
>   #4  0x00007f40e5d910ed in _int_free (av=0x7f40c8000020,
> p=0x7f40c80079e0, have_lock=0) at malloc.c:4201
>   #5  0x00007f40e61a9a4f in virFree (ptrptr=0x7f40c8003b60) at
> ../../../src/util/viralloc.c:348
>   #6  0x00007f40dd0cf8b1 in networkCreateInterfacePool
> (netdef=0x7f40840187f0) at ../../../src/network/bridge_driver.c:2849
>   #7  0x00007f40dd0d799c in networkStartNetworkExternal
> (obj=0x7f408400f720) at ../../../src/network/bridge_driver.c:2938
>   #8  networkStartNetwork (driver=driver@entry=0x7f408400a7a0,
> obj=0x7f408400f720) at ../../../src/network/bridge_driver.c:2938
>   #9  0x00007f40dd0d854d in networkCreate (net=0x7f40c8000c60) at
> ../../../src/network/bridge_driver.c:4013
>   #10 0x00007f40e63fac3f in virNetworkCreate (network=network@entry=0x7f40c8000c60)
> at ../../../src/libvirt-network.c:585
>   #11 0x0000560240e255d1 in remoteDispatchNetworkCreate
> (server=0x560240ea4280, msg=0x560240ee8200, args=0x7f40c8000c40,
> rerr=0x7f40e00ec9a0, client=<optimized out>) at
> ./remote/remote_daemon_dispatch_stubs.h:13570
>   #12 remoteDispatchNetworkCreateHelper (server=0x560240ea4280,
> client=<optimized out>, msg=0x560240ee8200, rerr=0x7f40e00ec9a0,
> args=0x7f40c8000c40, ret=0x0) at
> ./remote/remote_daemon_dispatch_stubs.h:13549
>   #13 0x00007f40e630c970 in virNetServerProgramDispatchCall
> (msg=0x560240ee8200, client=0x560240eea270, server=0x560240ea4280,
> prog=0x560240ee1520) at ../../../src/rpc/virnetserverprogram.c:430
>   #14 virNetServerProgramDispatch (prog=0x560240ee1520, server=server@entry=0x560240ea4280,
> client=0x560240eea270, msg=0x560240ee8200) at
> ../../../src/rpc/virnetserverprogram.c:302
>   #15 0x00007f40e6311c2c in virNetServerProcessMsg (msg=<optimized out>,
> prog=<optimized out>, client=<optimized out>, srv=0x560240ea4280) at
> ../../../src/rpc/virnetserver.c:136
>   #16 virNetServerHandleJob (jobOpaque=<optimized out>,
> opaque=0x560240ea4280) at ../../../src/rpc/virnetserver.c:153
>   #17 0x00007f40e62301af in virThreadPoolWorker (opaque=opaque@entry=0x560240e885f0)
> at ../../../src/util/virthreadpool.c:163
>   #18 0x00007f40e622f51c in virThreadHelper (data=<optimized out>) at
> ../../../src/util/virthread.c:196
>   #19 0x00007f40e5ef2609 in start_thread (arg=<optimized out>) at
> pthread_create.c:477
>   #20 0x00007f40e5e19293 in clone () at
> ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
>
> To manage notifications about this bug go to:
>
> https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1943481/+subscriptions
>
>