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
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