Re: [Qemu-devel] [PATCH v2 1/3] monitor: Allow add-fd to any specified fd set

[Corey Bryant <coreyb@linux.vnet.ibm.com>]

On 10/10/2012 05:49 PM, Eric Blake wrote:
> On 10/10/2012 08:20 AM, Corey Bryant wrote:
>> The first call to add an fd to an fd set was previously not
>> allowed to choose the fd set ID.  The ID was generated as
>> the first available and ensuing calls could add more fds by
>> specifying the fd set ID.  This change allows users to
>> choose the fd set ID on the first call.
>
> Unfortunately, it now allows the user to choose arbitrary integer set
> ids with large gaps, where previously, the user could only influence set
> ids by populating all intermediate ids.  That is, before this patch, a
> user would have to create 1000000 sets to have an id of 1000000 (if they
> didn't run out of memory first on all the earlier sets), but now they
> can have an id that large with just one set.  Or, taken further,
> previously, a user request of -9223372036854775808 would likely fail (if
> not, how beefy is your machine?), but now it can succeed and cause
> confusion because of integer wraparound.  Arbitrary set ids is not
> necessarily bad, but I think you need to add bounds-checking on the
> user's requested fdset_id to make sure it is positive.
>

I agree.  I'll add some set ID bounds checking in v3.

-- 
Regards,
Corey Bryant