Re: [Xen-devel] [PATCH 3/3] domctl: tighten XEN_DOMCTL_*_permission

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 01.05.14 at 17:37, <tim@xxxxxxx> wrote:
> At 15:24 +0100 on 30 Apr (1398867864), Jan Beulich wrote:
>> @@ -72,13 +72,11 @@ long arch_do_domctl(
>>          unsigned int np = domctl->u.ioport_permission.nr_ports;
>>          int allow = domctl->u.ioport_permission.allow_access;
>>  
>> -        ret = -EINVAL;
>> -        if ( (fp + np) > 65536 )
>> -            break;
>> -
>> -        if ( np == 0 )
>> -            ret = 0;
>> -        else if ( xsm_ioport_permission(XSM_HOOK, d, fp, fp + np - 1, 
>> allow) 
> )
>> +        if ( (fp + np - 1) < fp || (fp + np) > 0x10000 )
>> +            ret = -EINVAL;
> 
> I think this fails if (fp + np) overflows exactly to 0.
> How about 'if ( (fp + np) <= fp || (fp + np) > 0x10000 )' ?

You're right, will fix.

Jan


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