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Re: [libvirt] [PATCH] qemu_agent: Remove agent reference only when disposing it



On 10.01.2013 01:59, Eric Blake wrote:
> On 01/09/2013 06:30 AM, Michal Privoznik wrote:
>> https://bugzilla.redhat.com/show_bug.cgi?id=892079
>>
>> With current code, if user calls virDomainPMSuspendForDuration()
>> followed by virDomainDestroy(), the former API checks for qemu agent
>> presence, which will evaluate as true (if agent is configured). While
>> talking to qemu agent, the qemu driver is unlocked, so the latter API
>> starts executing.  However, if machine dies meanwhile, libvirtd gets
>> EOF on the agent socket and qemuProcessHandleAgentEOF() is called. The
>> handler clears reference to qemu agent while the destroy API already
>> holding a reference to it. This leads to NULL dereferencing later in
>> the code. Therefore, the agent pointer should be set to NULL only if
>> we are the exclusive owner of it.
>> ---
>>
>> There's a reproducer in the BZ. It doesn't have to be a windows guest,
>> I was able to reproduce with F17 guest as well.
>>
>>  src/qemu/qemu_process.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> ACK.
> 

Thanks, pushed.

Michal


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