On Wed, 6 Mar 2019 08:41:04 +0000, Stefan Hajnoczi <stefanha@xxxxxxxxx> wrote:
> On Tue, Mar 05, 2019 at 08:01:45PM +0200, Adalbert Lazăr wrote:
>
> Thanks for the patch, Adalbert! Please add a Signed-off-by tag so your
> patch can be merged (see Documentation/process/submitting-patches.rst
> Chapter 11 for details on the Developer's Certificate of Origin).
>
> > static int virtio_transport_reset_no_sock(struct virtio_vsock_pkt *pkt)
> > {
> > + const struct virtio_transport *t;
> > struct virtio_vsock_pkt_info info = {
> > .op = VIRTIO_VSOCK_OP_RST,
> > .type = le16_to_cpu(pkt->hdr.type),
> > @@ -680,7 +681,11 @@ static int virtio_transport_reset_no_sock(struct virtio_vsock_pkt *pkt)
> > if (!pkt)
> > return -ENOMEM;
> >
> > - return virtio_transport_get_ops()->send_pkt(pkt);
> > + t = virtio_transport_get_ops();
> > + if (!t)
> > + return -ENOTCONN;
>
> pkt is leaked here. This is an easy mistake to make because the code is
> unclear.
Thank you for your kind words :)
> The pkt argument is the received packet that we must reply to.
> The reply packet is allocated just before line 680 and must be free
> explicitly for return -ENOTCONN.
>
> You can avoid the leak and make the code easier to read like this:
>
> struct virtio_vsock_pkt *reply;
>
> ...
>
> ------ avoid reusing 'pkt'
> v
> reply = virtio_transport_alloc_pkt(&info, 0, ...);
> if (!reply)
> return -ENOMEM;
>
> t = virtio_transport_get_ops();
> if (!t) {
> virtio_transport_free_pkt(reply); <-- prevent memory leak
> return -ENOTCONN;
> }
> return t->send_pkt(reply);
What do you think about Stefano's suggestion, to move the check above
the line were the reply is allocated?
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