On Mon, Jul 31, 2023 at 02:02:59PM +0200, Greg KH wrote: > 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? It was posted as: https://lore.kernel.org/all/20230714224538.404793-1-dmitry.torokhov@xxxxxxxxx/ and I believe Alex Williamson is planning to take it through VFIO tree. Thanks. -- Dmitry