[libvirt] Potential segfault in udev driver

[Daniel P. Berrange]

On Sun, Jan 24, 2010 at 11:07:59PM +0100, Matthias Bolte wrote:
> udevDeviceMonitorStartup registers udevEventHandleCallback as event
> handle, but doesn't store the returned watch id to remove it later on.
> Also it's not clear to me whether the event handle should be register
> for the whole lifetime of the udev driver instance or just for the
> udevEnumerateDevices call.

The handler should be active for the lifetime of libvirtd, since the
udev driver has to detect hotplug/unplug events over time. 

> 
> If for example the call to udevSetupSystemDev [1] fails
> udevDeviceMonitorShutdown is called to cleanup, but
> udevEventHandleCallback is still registered and may be called when
> driverState is NULL again, resulting in a segfault in
> udevEventHandleCallback.
> 
> So to solve this the udevEventHandleCallback event handle must be
> removed at the appropriate place.

Yes, sounds like its needs to be removed in the failure path there

Daniel
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