On Wed, Mar 22, 2017 at 03:43:17PM +0100, Michal Privoznik wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1434882 Imagine the following scenario: 1) virsh net-start default 2) virsh start myFavouriteDomain 3) virsh net-destroy default 4) virsh destroy myFavouriteDomain (assuming myFavouriteDomain has an interface from default network) Regardless of how unlikely this scenario looks like, we should not crash. The problem is, on net-destroy in networkShutdownNetworkVirtual() the virMacMap module is unrefed, but the stale pointer is kept around. Thus when the domain destroy procedure comes in, networkReleaseActualDevice() and subsequently networkMacMgrDel() is called. This function sees the stale pointer and starts calling the virMacMap module APIs which work over freed memory. Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> --- src/network/bridge_driver.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c index 0ea8e2348..3fcdd702e 100644 --- a/src/network/bridge_driver.c +++ b/src/network/bridge_driver.c @@ -2488,7 +2488,8 @@ networkShutdownNetworkVirtual(virNetworkDriverStatePtr driver, if (network->def->bandwidth) virNetDevBandwidthClear(network->def->bridge); - virObjectUnref(network->macmap); + if (!virObjectUnref(network->macmap)) + network->macmap = NULL;
You should set the macmap to NULL unconditionally. If someone is holding a reference to it, they can decide when to use it. And they can unref it just before you're going to use it. And you should never use anything you don't have reference for. And moreover, the network has always the only reference, nobody else takes this pointer anywhere. ACK with that changed. The macmap could also be part of the network, created when the network was defined, but it would have a "enabled" boolean which would be toggled on network start-up. That way you wouldn't have to deal with references at all. They are useless in this case anyway, as mentioned above.
if (network->radvdPid > 0) {
char *radvdpidbase;
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2.11.0
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