Re: [PATCH v2] qemu: fix libvirtd crash when querying halted cpus info

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15-Nov-16 16:44, Maxim Nestratov пишет:

It was introduced by commit 7a51d9ebb, which started to use
monitor commands without job acquiring, which is unsafe and leads
to simultaneous access to vm->mon structure by different threads.

Crash backtrace is the following (shortened):

Program received signal SIGSEGV, Segmentation fault.
qemuMonitorSend (mon=mon@entry=0x7f4ef4000d20, msg=msg@entry=0x7f4f18e78640) at qemu/qemu_monitor.c:1011
1011        while (!mon->msg->finished) {

0  qemuMonitorSend () at qemu/qemu_monitor.c:1011
1  0x00007f691abdc720 in qemuMonitorJSONCommandWithFd () at qemu/qemu_monitor_json.c:298
2  0x00007f691abde64a in qemuMonitorJSONCommand at qemu/qemu_monitor_json.c:328
3  qemuMonitorJSONQueryCPUs at qemu/qemu_monitor_json.c:1408
4  0x00007f691abcaebd in qemuMonitorGetCPUInfo g@entry=false) at qemu/qemu_monitor.c:1931
5  0x00007f691ab96863 in qemuDomainRefreshVcpuHalted at qemu/qemu_domain.c:6309
6  0x00007f691ac0af99 in qemuDomainGetStatsVcpu at qemu/qemu_driver.c:18945
7  0x00007f691abef921 in qemuDomainGetStats  at qemu/qemu_driver.c:19469
8  qemuConnectGetAllDomainStats at qemu/qemu_driver.c:19559
9  0x00007f693382e806 in virConnectGetAllDomainStats at libvirt-domain.c:11546
10 0x00007f6934470c40 in remoteDispatchConnectGetAllDomainStats at remote.c:6267

(gdb) p mon->msg
$1 = (qemuMonitorMessagePtr) 0x0

This change fixes it by calling qemuDomainRefreshVcpuHalted only when job is acquired.

Signed-off-by: Maxim Nestratov <mnestratov@xxxxxxxxxxxxx>
---
  src/qemu/qemu_driver.c | 17 +++++++++++------
  1 file changed, 11 insertions(+), 6 deletions(-)

Ignore this version please. The next one is sent with "syntax-check".

Maxim

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