On Tue, Mar 26, 2024 at 02:39:28PM +0100, Stefano Garzarella wrote: > libvhost-user will panic when receiving VHOST_USER_GET_INFLIGHT_FD > message if MFD_ALLOW_SEALING is not defined, since it's not able > to create a memfd. > > VHOST_USER_GET_INFLIGHT_FD is used only if > VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD is negotiated. So, let's mask > that feature if the backend is not able to properly handle these > messages. > > Signed-off-by: Stefano Garzarella <sgarz...@redhat.com> > --- > subprojects/libvhost-user/libvhost-user.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/subprojects/libvhost-user/libvhost-user.c > b/subprojects/libvhost-user/libvhost-user.c > index a11afd1960..1c361ffd51 100644 > --- a/subprojects/libvhost-user/libvhost-user.c > +++ b/subprojects/libvhost-user/libvhost-user.c > @@ -1674,6 +1674,16 @@ vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg > *vmsg) > features |= dev->iface->get_protocol_features(dev); > } > > + /* > + * If MFD_ALLOW_SEALING is not defined, we are not able to handle > + * VHOST_USER_GET_INFLIGHT_FD messages, since we can't create a memfd. > + * Those messages are used only if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD > + * is negotiated. A device implementation can enable it, so let's mask > + * it to avoid a runtime panic. > + */ > +#ifndef MFD_ALLOW_SEALING > + features &= ~(1ULL << VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD); > +#endif
Masking the feature out of advertisement is obviously correct. But should we also fix the code for handling VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD to return an error to any client that requests it in error when the feature was not advertised, instead of panicking? > vmsg_set_reply_u64(vmsg, features); > return true; > } > -- > 2.44.0 > -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org
