Stefano Garzarella
2023-Jun-05 08:23 UTC
[PATCH net] virtio/vsock: fix sock refcnt bug on owner set failure
On Wed, May 31, 2023 at 03:35:30AM +0000, Bobby Eshleman wrote:>On Thu, Jun 01, 2023 at 09:58:47AM +0200, Stefano Garzarella wrote: >> On Wed, May 31, 2023 at 07:47:32PM +0000, Bobby Eshleman wrote: >> > Previous to setting the owner the socket is found via >> > vsock_find_connected_socket(), which returns sk after a call to >> > sock_hold(). >> > >> > If setting the owner fails, then sock_put() needs to be called. >> > >> > Fixes: f9d2b1e146e0 ("virtio/vsock: fix leaks due to missing skb owner") >> > Signed-off-by: Bobby Eshleman <bobby.eshleman at bytedance.com> >> > --- >> > net/vmw_vsock/virtio_transport_common.c | 1 + >> > 1 file changed, 1 insertion(+) >> > >> > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >> > index b769fc258931..f01cd6adc5cb 100644 >> > --- a/net/vmw_vsock/virtio_transport_common.c >> > +++ b/net/vmw_vsock/virtio_transport_common.c >> > @@ -1343,6 +1343,7 @@ void virtio_transport_recv_pkt(struct virtio_transport *t, >> > >> > if (!skb_set_owner_sk_safe(skb, sk)) { >> > WARN_ONCE(1, "receiving vsock socket has sk_refcnt == 0\n"); >> > + sock_put(sk); >> >> Did you have any warning, issue here? >> >> IIUC skb_set_owner_sk_safe() can return false only if the ref counter >> is 0, so calling a sock_put() on it should have no effect except to >> produce a warning. >> > >Oh yeah, you're totally right. I did not recall how >skb_set_owner_sk_safe() worked internally and thought I'd introduced an >uneven hold/put count with that prior patch when reading through the >code again. I haven't seen any live issue, just misread the code. > >Sorry about that, feel free to ignore this patch.No problem ;-) Maybe we should add a comment on it. Thanks, Stefano