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qemu: fix libvirtd crash when querying halted cpus info

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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@virtuozzo.com>
This commit is contained in:
Maxim Nestratov 2016-11-02 18:56:49 +03:00
parent 70d15c9ac6
commit 007fb4388f
1 changed files with 12 additions and 6 deletions
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18
src/qemu/qemu_driver.c
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@ -18978,7 +18978,7 @@ qemuDomainGetStatsVcpu(virQEMUDriverPtr driver,
virDomainObjPtr dom,
virDomainStatsRecordPtr record,
int *maxparams,
unsigned int privflags ATTRIBUTE_UNUSED)
unsigned int privflags)
{
size_t i;
int ret = -1;
@ -19005,10 +19005,16 @@ qemuDomainGetStatsVcpu(virQEMUDriverPtr driver,
VIR_ALLOC_N(cpuwait, virDomainDefGetVcpus(dom->def)) < 0)
goto cleanup;
if (qemuDomainRefreshVcpuHalted(driver, dom,
QEMU_ASYNC_JOB_NONE) == 0 &&
VIR_ALLOC_N(cpuhalted, virDomainDefGetVcpus(dom->def)) < 0)
goto cleanup;
if (HAVE_JOB(privflags) && virDomainObjIsActive(dom)) {
if (qemuDomainRefreshVcpuHalted(driver, dom,
QEMU_ASYNC_JOB_NONE) < 0) {
/* it's ok to be silent and go ahead, because halted vcpu info
* wasn't here from the beginning */
virResetLastError();
} else if (VIR_ALLOC_N(cpuhalted, virDomainDefGetVcpus(dom->def)) < 0) {
goto cleanup;
}
}
if (qemuDomainHelperGetVcpus(dom, cpuinfo, cpuwait,
virDomainDefGetVcpus(dom->def),
@ -19462,7 +19468,7 @@ static struct qemuDomainGetStatsWorker qemuDomainGetStatsWorkers[] = {
{ qemuDomainGetStatsState, VIR_DOMAIN_STATS_STATE, false },
{ qemuDomainGetStatsCpu, VIR_DOMAIN_STATS_CPU_TOTAL, false },
{ qemuDomainGetStatsBalloon, VIR_DOMAIN_STATS_BALLOON, true },
{ qemuDomainGetStatsVcpu, VIR_DOMAIN_STATS_VCPU, false },
{ qemuDomainGetStatsVcpu, VIR_DOMAIN_STATS_VCPU, true },
{ qemuDomainGetStatsInterface, VIR_DOMAIN_STATS_INTERFACE, false },
{ qemuDomainGetStatsBlock, VIR_DOMAIN_STATS_BLOCK, true },
{ qemuDomainGetStatsPerf, VIR_DOMAIN_STATS_PERF, false },