[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [libvirt] [PATCH] Add several missing vir*Free calls in libvirtd's remote code



On Sat, Jun 12, 2010 at 06:32:55PM +0200, Matthias Bolte wrote:
> Justin Clift reported a problem with adding virStoragePoolIsPersistent
> to virsh's pool-info command, resulting in a strange problem. Here's
> an example:
> 
>     virsh # pool-create-as images_dir3 dir - - - - "/home/images2"
>     Pool images_dir3 created
> 
>     virsh # pool-info images_dir3
>     Name:           images_dir3
>     UUID:           90301885-94eb-4ca7-14c2-f30b25a29a36
>     State:          running
>     Capacity:       395.20 GB
>     Allocation:     30.88 GB
>     Available:      364.33 GB
> 
>     virsh # pool-destroy images_dir3
>     Pool images_dir3 destroyed
> 
> At this point the images_dir3 pool should be gone (because it was
> transient) and we should be able to create a new pool with the same name:
> 
>     virsh # pool-create-as images_dir3 dir - - - - "/home/images2"
>     Pool images_dir3 created
> 
>     virsh # pool-info images_dir3
>     Name:           images_dir3
>     UUID:           90301885-94eb-4ca7-14c2-f30b25a29a36
>     error: Storage pool not found
> 
> The new pool got the same UUID as the first one, but we didn't specify
> one. libvirt should have picked a random UUID, but it didn't.
> 
> It turned out that virStoragePoolIsPersistent leaks a reference to the
> storage pool object (actually remoteDispatchStoragePoolIsPersistent does).
> As a result, pool-destroy doesn't remove the virStoragePool for the
> "images_dir3" pool from the virConnectPtr's storagePools hash on libvirtd's
> side. Then the second pool-create-as get's the stale virStoragePool object
> associated with the "images_dir3" name. But this object has the old UUID.
> 
> This commit ensures that all get_nonnull_* and make_nonnull_* calls for
> libvirt objects are matched properly with vir*Free calls. This fixes the
> reference leaks and the reported problem.
> 
> All remoteDispatch*IsActive and remoteDispatch*IsPersistent functions were
> affected. But also remoteDispatchDomainMigrateFinish2 was affected in the
> success path. I wonder why that didn't surface earlier. Probably because
> domainMigrateFinish2 is executed on the destination host and in the common
> case this connection is opened especially for the migration and gets closed
> after the migration is done. So there was no chance to run into a problem
> because of the leaked reference.

ACK, looks good.

Wonder why coverity hadn't flagged these memory leaks before..

Daniel
-- 
|: Red Hat, Engineering, London    -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :|
|: http://autobuild.org        -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-   F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]