Steps to reproduce on Focal (shutdown-on-runtime)
---
LXD virtual machine
lxc exec lp2059272-focal -- su - ubuntu
lxc exec lp2059272-focal -- su - ubuntu
Latest Packages and Debug Symbols:
cat <<EOF | sudo tee /etc/apt/sources.list.d/proposed.list
deb http://archive.ubuntu.com/ubuntu focal-proposed main universe
deb http://ddebs.ubuntu.com focal-proposed main restricted
EOF
cat <<EOF | sudo tee /etc/apt/preferences.d/proposed
Package: *
Pin: release a=focal-proposed
Pin-Priority: 400
EOF
sudo apt install --yes --no-install-recommends gdb qemu-system-x86
ubuntu-dbgsym-keyring
sudo apt install --yes --no-install-recommends -t focal-proposed
libvirt{0,-daemon{,-driver-qemu,-system}}{,-dbgsym} libvirt-clients
$ dpkg -l | awk '$2 ~ /^libvirt/ { print $2, $3 }'
libvirt-clients 6.0.0-0ubuntu8.17
libvirt-daemon 6.0.0-0ubuntu8.17
libvirt-daemon-dbgsym 6.0.0-0ubuntu8.17
libvirt-daemon-driver-qemu 6.0.0-0ubuntu8.17
libvirt-daemon-driver-qemu-dbgsym 6.0.0-0ubuntu8.17
libvirt-daemon-system 6.0.0-0ubuntu8.17
libvirt-daemon-system-systemd 6.0.0-0ubuntu8.17
libvirt0:amd64 6.0.0-0ubuntu8.17
libvirt0-dbgsym:amd64 6.0.0-0ubuntu8.17
Stop libvirt systemd units
sudo systemctl stop 'libvirtd*'
Start libvirt in GDB
sudo gdb \
-iex 'set confirm off' \
-iex 'set pagination off' \
-ex 'set non-stop on' \
-ex 'handle SIGTERM nostop noprint pass' \
-ex 'add-symbol-file /usr/sbin/libvirtd' \
-ex 'add-symbol-file /usr/lib/x86_64-linux-gnu/libvirt.so.0' \
-ex 'add-symbol-file /usr/lib/x86_64-linux-gnu/libvirt-qemu.so.0' \
-ex 'add-symbol-file
/usr/lib/x86_64-linux-gnu/libvirt/connection-driver/libvirt_driver_qemu.so' \
/usr/sbin/libvirtd
Add breakpoints for qemu driver cleanup and device deleted event
b qemuStateCleanup
b processDeviceDeletedEvent
run
Start test VM with an USB mouse device
cat <<-EOF >test-vm.xml
<domain type='qemu'>
<name>test-vm</name>
<os>
<type>hvm</type>
</os>
<memory unit='MiB'>32</memory>
<vcpu>1</vcpu>
<devices>
<input type='mouse' bus='usb'/>
</devices>
</domain>
EOF
virsh define test-vm.xml
virsh start test-vm
$ virsh list
Id Name State
-------------------------
1 test-vm running
Delete the USB mouse device
DEVICE_ID=$(virsh qemu-monitor-command test-vm --hmp 'info qtree' |
grep 'dev: usb-mouse' | cut -d'"' -f2)
virsh qemu-monitor-command test-vm --hmp "device_del $DEVICE_ID"
Back to GDB
Thread 20 "libvirtd" hit Breakpoint 2, 0x00007f316df78ffe in
processDeviceDeletedEvent (devAlias=<optimized out>, vm=0x7f3178016890,
driver=0x7f317802edd0) at ../../../src/qemu/qemu_driver.c:4879
Add breakpoint to domain status XML save, and continue the thread above
b virDomainObjSave
t 20
c
Thread 20 "libvirtd" hit Breakpoint 3, virDomainObjSave
(obj=0x7f3178016890, xmlopt=0x7f3178037780, statusDir=0x7f317800aa40
"/run/libvirt/qemu") at ../../../src/conf/domain_conf.c:29157
Check the backtrace of the domain status XML save function, coming from
device deleted event
(gdb) bt
#0 virDomainObjSave (obj=0x7f3178016890, xmlopt=0x7f3178037780,
statusDir=0x7f317800aa40 "/run/libvirt/qemu") at
../../../src/conf/domain_conf.c:29157
#1 0x00007f316df790d7 in processDeviceDeletedEvent
(devAlias=0x5654c5839310 "input0", vm=0x7f3178016890, driver=0x7f317802edd0) at
../../../src/qemu/qemu_driver.c:4303
#2 qemuProcessEventHandler (data=0x5654c5879e80,
opaque=0x7f317802edd0) at ../../../src/qemu/qemu_driver.c:4879
#3 0x00007f318b59f1af in virThreadPoolWorker
(opaque=opaque@entry=0x5654c5838160) at ../../../src/util/virthreadpool.c:163
#4 0x00007f318b59e51c in virThreadHelper (data=<optimized out>) at
../../../src/util/virthread.c:196
#5 0x00007f318b25f609 in start_thread () from
/lib/x86_64-linux-gnu/libpthread.so.0
#6 0x00007f318b184353 in clone () from /lib/x86_64-linux-gnu/libc.so.6
Leave the thread at this point
Let's trigger the shutdown path
$ sudo kill $(pidof libvirtd)
Thread 1 "libvirtd" hit Breakpoint 1, qemuStateCleanup () at
../../../src/qemu/qemu_driver.c:1118
Check there are 2 stopped threads: cleanup and domain status XML save
(gdb) i th
Id Target Id Frame
1 Thread 0x7f3187745b40 (LWP 4969) "libvirtd" qemuStateCleanup ()
at ../../../src/qemu/qemu_driver.c:1118
2 Thread 0x7f31872af700 (LWP 4973) "libvirtd" (running)
...
18 Thread 0x7f315e7fc700 (LWP 4989) "libvirtd" (running)
* 20 Thread 0x7f315dffb700 (LWP 5045) "libvirtd" virDomainObjSave
(obj=0x7f3178016890, xmlopt=0x7f3178037780, statusDir=0x7f317800aa40
"/run/libvirt/qemu") at ../../../src/conf/domain_conf.c:29157
Confirm the qemu driver's domain xml formatter/options is
set/referenced:
t 20
(gdb) p xmlopt.privateData.format
$1 = (virDomainXMLPrivateDataFormatFunc) 0x7f316ded3810
<qemuDomainObjPrivateXMLFormat>
(gdb) p/x xmlopt.parent
$3 = {u = {dummy_align1 = 0x1cafe0026, dummy_align2 = 0x1cafe0026, s =
{magic = 0xcafe0026, refs = 0x1}}, klass = 0x7f3178037750}
Let the cleanup function and shutdown path finish
t 1
c &
Check the formatter/options again; it is *NO* longer referenced:
t 20
(gdb) p xmlopt.privateData.format
$4 = (virDomainXMLPrivateDataFormatFunc) 0x0
(gdb) p/x xmlopt.parent
$5 = {u = {dummy_align1 = 0x7f317805d170, dummy_align2 =
0x7f317805d170, s = {magic = 0x7805d170, refs = 0x7f31}}, klass =
0x7f3178000080}
The object data is zeroed in the last unreference in Focal,
and its contents changed, as this is really an use-after-free
(another thread might get/use that memory).
Check the VM status XML *before* the save function finishes:
$ sudo grep -e '<domstatus' -e '<domain' -e 'monitor path'
/run/libvirt/qemu/test-vm.xml
<domstatus state='running' reason='booted' pid='5031'>
<monitor path='/var/lib/libvirt/qemu/domain-1-test-vm/monitor.sock'
type='unix'/>
<domain type='qemu' id='1'>
Let the save function continue, and libvirt finishes shutting down:
(gdb) c
Continuing.
...
[Inferior 1 (process 4969) exited normally]
(gdb) q
Check the VM status XML *after*:
$ sudo grep -e '<domstatus' -e '<domain' -e 'monitor path'
/run/libvirt/qemu/test-vm.xml
<domstatus state='running' reason='booted' pid='5031'>
<domain type='qemu' id='1'>
It no longer has the 'monitor path' tag/field.
Now, the next time libvirtd starts, it fails to parse that XML:
$ sudo systemctl start libvirtd.service
$ journalctl -b -u libvirtd.service | grep error
$ journalctl -b -u libvirtd.service | grep -A1 error
Mar 30 21:58:37 lp2059272-focal libvirtd[5063]: internal error: no
monitor path
Mar 30 21:58:37 lp2059272-focal libvirtd[5063]: Failed to load config
for domain 'test-vm'
And libvirt is not aware of the domain, and cannot manage it:
$ virsh list
Id Name State
--------------------
$ virsh list --all
Id Name State
--------------------------
- test-vm shut off
Even though it is still running:
$ pgrep -af qemu-system-x86_64 | cut -d, -f1
5031 /usr/bin/qemu-system-x86_64 -name guest=test-vm
Stop it manually:
$ sudo kill $(sudo cat /run/libvirt/qemu/test-vm.pid)
$ sudo rm /run/libvirt/qemu/test-vm.{xml,pid}
Start libvirt:
sudo systemctl start libvirtd.service
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2059272
Title:
libvirt domain is not listed/managed after libvirt restart with
messages "internal error: no monitor path" and "Failed to load config
for domain"
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https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/2059272/+subscriptions
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