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References: <20180621124937.166549-1-eblake@redhat.com>
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-ID: <f1365a2f-d63a-bbd2-32b5-d1e6e4fc1888@virtuozzo.com>
Date: Thu, 21 Jun 2018 15:52:49 +0300
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Subject: Re: [Qemu-devel] [PATCH] nbd/server: Reject 0-length block status
 request
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To: Eric Blake <eblake@redhat.com>, qemu-devel@nongnu.org
Cc: jsnow@redhat.com, qemu-block@nongnu.org, qemu-stable@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>

21.06.2018 15:49, 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.
>
> CC: qemu-stable@nongnu.org
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

> ---
>   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,


-- 
Best regards,
Vladimir