| Message ID | 20230531-b4-vsock-fix-refcnt-v1-1-0ed7b697cca5@bytedance.com (mailing list archive) |
|---|---|
| State | Rejected |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] virtio/vsock: fix sock refcnt bug on owner set failure | expand |
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@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. Best, Bobby
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@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. Thanks, Stefano
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@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
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); goto free_pkt; }
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@bytedance.com> --- net/vmw_vsock/virtio_transport_common.c | 1 + 1 file changed, 1 insertion(+) --- base-commit: 60cbd38bb0ad9e4395fba9c6994f258f1d6cad51 change-id: 20230531-b4-vsock-fix-refcnt-b7b1558c0820 Best regards,