Messages in this thread | | | Date | Thu, 3 Aug 2023 15:36:03 -0700 | From | Dmitry Torokhov <> | Subject | Re: [PATCH v3 1/2] kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() |
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On Thu, Aug 03, 2023 at 01:38:12PM -0600, Alex Williamson wrote: > On Fri, 14 Jul 2023 15:45:32 -0700 > Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote: > > > kvm_vfio_group_add() creates kvg instance, links it to kv->group_list, > > and calls kvm_vfio_file_set_kvm() with kvg->file as an argument after > > dropping kv->lock. If we race group addition and deletion calls, kvg > > instance may get freed by the time we get around to calling > > kvm_vfio_file_set_kvm(). > > > > Previous iterations of the code did not reference kvg->file outside of > > the critical section, but used a temporary variable. Still, they had > > similar problem of the file reference being owned by kvg structure and > > potential for kvm_vfio_group_del() dropping it before > > kvm_vfio_group_add() had a chance to complete. > > > > Fix this by moving call to kvm_vfio_file_set_kvm() under the protection > > of kv->lock. We already call it while holding the same lock when vfio > > group is being deleted, so it should be safe here as well. > > > > Fixes: 2fc1bec15883 ("kvm: set/clear kvm to/from vfio_group when group add/delete") > > Reviewed-by: Alex Williamson <alex.williamson@redhat.com> > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > > --- > > Applied series to vfio next branch for v6.6. There's a minor rebase > involved, so please double check the results: > > https://github.com/awilliam/linux-vfio/commits/next
Looks good to me, thanks!
-- Dmitry
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