Re: [Qemu-devel] [PATCH 3/3] virtio-blk: Treat read/write beyond end as invalid

[Markus Armbruster <armbru@redhat.com>]

Markus Armbruster <armbru@redhat.com> writes:

> Stefan Hajnoczi <stefanha@redhat.com> writes:
>
>> On Thu, Jun 05, 2014 at 02:15:36PM +0200, Markus Armbruster wrote:
>>> +    if (sector > total_sectors || nb_sectors > total_sectors - sector) {
>>> +        return false;
>>> +    }
>>
>> if (sector >= total_sectors || ...) {
>
> I suspect reading bdrv_check_byte_request() put the '>' in my brain:
>
>     if ((offset > len) || (len - offset < size))
>         return -EIO;
>
> Don't we need offset >= len here?

Just remembered: we don't, because we allow I/O at offset len provided
size is zero.

Same reasoning applies to my patch.