On Fri, Apr 06, 2018 at 06:53 PM +0200, John Ferlan <jferlan@xxxxxxxxxx> wrote:
> Because we allow a QEMU_JOB_DESTROY to occur while we're starting
> up and we drop the @vm lock prior to qemuMonitorOpen, it's possible
> that a domain destroy operation "wins" the race, calls qemuProcessStop
> which will free and reinitialize priv->monConfig. Depending on the
> exact timing either qemuMonitorOpen will be passed a NULL @config
> variable or it will be using free'd (and possibly reclaimed) memory
> as the @config parameter - neither of which is good.
>
> Resolve this by localizing the @monConfig, taking an extra reference,
> and then once we get the @vm lock again removing our reference since
> we are done with it.
>
> Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx>
> ---
> src/qemu/qemu_process.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index a8dab92dd6..988c6b1537 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -1776,6 +1776,7 @@ qemuConnectMonitor(virQEMUDriverPtr driver, virDomainObjPtr vm, int asyncJob,
> qemuDomainObjPrivatePtr priv = vm->privateData;
> qemuMonitorPtr mon = NULL;
> unsigned long long timeout = 0;
> + virDomainChrSourceDefPtr monConfig;
>
> if (qemuSecuritySetDaemonSocketLabel(driver->securityManager, vm->def) < 0) {
> VIR_ERROR(_("Failed to set security context for monitor for %s"),
> @@ -1794,10 +1795,12 @@ qemuConnectMonitor(virQEMUDriverPtr driver, virDomainObjPtr vm, int asyncJob,
> virObjectRef(vm);
>
> ignore_value(virTimeMillisNow(&priv->monStart));
> + monConfig = priv->monConfig;
> + virObjectRef(monConfig);
> virObjectUnlock(vm);
>
> mon = qemuMonitorOpen(vm,
> - priv->monConfig,
> + monConfig,
> priv->monJSON,
> timeout,
> &monitorCallbacks,
> @@ -1813,6 +1816,7 @@ qemuConnectMonitor(virQEMUDriverPtr driver, virDomainObjPtr vm, int asyncJob,
>
> virObjectLock(vm);
> virObjectUnref(vm);
> + virObjectUnref(monConfig);
Only for consistency: I would first unref @monConfig and then do the
unref for @vm.
> priv->monStart = 0;
>
> if (!virDomainObjIsActive(vm)) {
> --
> 2.13.6
>
> --
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Beste Grüße / Kind regards
Marc Hartmayer
IBM Deutschland Research & Development GmbH
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