On Mon, Apr 09, 2018 at 04:25 PM +0200, Marc Hartmayer <mhartmay@linux.vnet.ibm.com> wrote:
On Fri, Apr 06, 2018 at 06:53 PM +0200, John Ferlan <jferlan@redhat.com> 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@redhat.com> --- 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.
With this change: Reviewed-by: Marc Hartmayer <mhartmay@linux.vnet.ibm.com>
priv->monStart = 0;
if (!virDomainObjIsActive(vm)) { -- 2.13.6
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-- Beste Grüße / Kind regards Marc Hartmayer
IBM Deutschland Research & Development GmbH Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294
-- Beste Grüße / Kind regards Marc Hartmayer IBM Deutschland Research & Development GmbH Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294