On Fri, Feb 11, 2022 at 07:14:30AM +0100, Laszlo Ersek wrote: > On 02/10/22 16:38, Eric Blake wrote: > > Our nbd plugin has always properly checked for asynch errors (and thus > > has never been at risk of a vulnerability similar to CVE-2022-0485 > > just fixed in nbdcopy). What's more, the nbdkit core guarantees > > (since commit b1ce255e in 2019, v1.13.1) that the buffer handed to a > > .pread callback has been pre-sanitized to not leak heap contents, > > regardless of how buggy a plugin might be (see > > server/protocol.c:protocol_recv_request_send_reply(), which uses > > server/threadlocal.c:threadlocal_buffer() for a safe buffer). Thus, > > we do not need libnbd to spend time re-initializing the buffer, if > > libnbd is new enough to give us that knob. > > --- > >
> > +#if LIBNBD_HAVE_NBD_SET_PREAD_INITIALIZE > > + /* nbdkit guarantees that the buffers passed to our .pread callback > > + * are pre-initialized; and we in turn ensure that the buffer is not > > + * dereferenced if the NBD server replied with an error. Thus, we > > + * are safe opting in to this libnbd speedup. > > + */ > > + if (nbd_set_pread_initialize (h->nbd, false) == -1) > > + goto errnbd; > > #endif > > if (dynamic_export && uri) { > > #if LIBNBD_HAVE_NBD_SET_OPT_MODE > > > > hahaha, this was real quick ;) I don't know if the speedy pun was intentional ;) Now pushed as 31997b25. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org _______________________________________________ Libguestfs mailing list Libguestfs@redhat.com https://listman.redhat.com/mailman/listinfo/libguestfs