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

On 02.11.2016 17:29, Viktor Mihajlovski wrote: > On 02.11.2016 16:56, Maxim Nestratov wrote: >> 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(a)virtuozzo.com&gt; >> --- >> src/qemu/qemu_driver.c | 20 +++++++++++++------- >> 1 file changed, 13 insertions(+), 7 deletions(-) > [...] > Argh ... this fell through the cracks when I moved the code from > vcpuinfo to domstats. Thanks for catching and fixing that one. > It would be nice if the fix could be pushed before the next release freeze. Thanks!