[libvirt] [PATCH] qemu: add pointer check in qemuMonitorLastError
Michal Privoznik
mprivozn at redhat.com
Mon Oct 7 15:27:36 UTC 2019
On 9/19/19 10:01 AM, Xu Yandong wrote:
> We found a exception when libvirt occurrs segmentation fault.
> thread 1 is waiting object lock in qemuConnectMonitor,
> qemu process exits and sends EOF event as well, so thread 2 invokes
> qemuMonitorLastError but pointer mon is NULL.
>
> Signed-off-by: Xu Yandong <xuyandong2 at huawei.com>
> ---
> src/qemu/qemu_monitor.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
> index aa230b3306..28f18391a5 100644
> --- a/src/qemu/qemu_monitor.c
> +++ b/src/qemu/qemu_monitor.c
> @@ -1103,7 +1103,7 @@ qemuMonitorSend(qemuMonitorPtr mon,
> virErrorPtr
> qemuMonitorLastError(qemuMonitorPtr mon)
> {
> - if (mon->lastError.code == VIR_ERR_OK)
> + if (!mon || mon->lastError.code == VIR_ERR_OK)
> return NULL;
>
> return virErrorCopyNew(&mon->lastError);
>
This works, but I think we need a better approach. The problem is, we
register monitor FD into our event loop with unlocked @vm and only after
that we try to lock @vm back and set priv->mon = mon (this is all done
in qemuConnectMonitor()). I have better fix in mind but I have to run
now, will post it tomorrow, if that's okay with you.
Michal
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