On Mon, Jul 10, 2023 at 03:20:31PM -0700, Dmitry Torokhov 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().
>
> 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: ba70a89f3c2a ("vfio: Change vfio_group_set_kvm() to vfio_file_set_kvm()")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> ---
> virt/kvm/vfio.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
> index 9584eb57e0ed..cd46d7ef98d6 100644
> --- a/virt/kvm/vfio.c
> +++ b/virt/kvm/vfio.c
> @@ -179,10 +179,10 @@ static int kvm_vfio_group_add(struct kvm_device *dev, unsigned int fd)
> list_add_tail(&kvg->node, &kv->group_list);
>
> kvm_arch_start_assignment(dev->kvm);
> + kvm_vfio_file_set_kvm(kvg->file, dev->kvm);
>
> mutex_unlock(&kv->lock);
>
> - kvm_vfio_file_set_kvm(kvg->file, dev->kvm);
> kvm_vfio_update_coherency(dev);
>
> return 0;
> --
> 2.41.0.255.g8b1d071c50-goog
What ever happened to this change? Did it end up in a KVM tree
somewhere?
thanks,
greg k-h
