Re: [PATCH] xen/memory: Reject out-of-range resource 'frame' values

[Jan Beulich <jbeulich@xxxxxxxx>]

On 29.01.2021 10:47, Andrew Cooper wrote:
> On 29/01/2021 09:40, Jan Beulich wrote:
>> On 29.01.2021 10:32, Andrew Cooper wrote:
>>> What's the likelihood that you'll choose to backport this?
>> Didn't consider this aspect yet. I think I wouldn't have picked
>> it without anyone asking for it to be backported.
>>
>>>   I can extend it if needs be.
>> Well, if that deletion of code gets committed in time, then of
>> course there's no real need to fiddle with it here.
> 
> This specific patch fixes a real bug on arm32 which will cause unsigned
> long + unsigned int to truncate together and permit certain values.

Why Arm32 only? Looking at current staging, there's no overflow
check at all on the grant part of the path. A suitably large
64-bit "frame" will allow the same behavior on 64-bit (wrapping
around through zero), afaict.

Jan