On 06/21/2018 08:49 AM, Eric Blake wrote:
> The NBD spec says that behavior is unspecified if the client
> requests 0 length for block status; but since the structured
> reply is documenting as returning a non-zero length, it's
> easier to just diagnose this with an EINVAL error than to
> figure out what to return.
>
Relevant section:
REQUEST TYPES / NBD_CMD_BLOCK_STATUS (7)
"A block status query request. Length and offset define the range of
interest. The client SHOULD NOT request a status length of 0; the
behavior of a server on such a request is unspecified although the
server SHOULD NOT disconnect."
Leave a little breadcrumb in the commit message because it's headed to
-stable.
> CC: [email protected]
> Signed-off-by: Eric Blake <[email protected]>
> ---
> nbd/server.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/nbd/server.c b/nbd/server.c
> index 9e1f2271784..493a926e063 100644
> --- a/nbd/server.c
> +++ b/nbd/server.c
> @@ -2007,6 +2007,10 @@ static coroutine_fn int nbd_handle_request(NBDClient
> *client,
> "discard failed", errp);
>
> case NBD_CMD_BLOCK_STATUS:
> + if (!request->len) {
> + return nbd_send_generic_reply(client, request->handle, -EINVAL,
> + "need non-zero length", errp);
> + }
> if (client->export_meta.valid &&
> client->export_meta.base_allocation) {
> return nbd_co_send_block_status(client, request->handle,
> blk_bs(exp->blk), request->from,
>
Looks correct assuming spec agrees.
Reviewed-by: John Snow <[email protected]>
