Re: [PATCH net v3 1/2] net: ethtool: reject an out of range hwtstamp provider index

[Kory Maincent <kory.maincent@bootlin.com>]

On 9/25/26 16:07, Nicolai Buchwitz wrote:
> Hi Kory
> 
> On 25.9.2026 15:55, Kory Maincent wrote:
> 
>> [...]
> 
>>>   static const struct nla_policy
>>>   ethnl_ts_hwtst_prov_policy[ETHTOOL_A_TS_HWTSTAMP_PROVIDER_MAX + 1] = {
>>> -    [ETHTOOL_A_TS_HWTSTAMP_PROVIDER_INDEX] = { .type = NLA_U32 },
>>> +    [ETHTOOL_A_TS_HWTSTAMP_PROVIDER_INDEX] =
>>> +        NLA_POLICY_FULL_RANGE(NLA_U32, &ethnl_ts_prov_index_range),
>>>       [ETHTOOL_A_TS_HWTSTAMP_PROVIDER_QUALIFIER] =
>>>           NLA_POLICY_MAX(NLA_U32, HWTSTAMP_PROVIDER_QUALIFIER_CNT - 1)
>>>   };
>>
>> I think you can simply do this:
>> [ETHTOOL_A_TS_HWTSTAMP_PROVIDER_INDEX] =
>>     NLA_POLICY_MAX(NLA_U32, INT_MAX),
> 
> That was my initial thought, but unfortunately it doesn't work. struct 
> nla_policy's
> .max is s16 and INT_MAX is truncated to -1. It ends up as U64_MAX in the 
> range check
> and in the end nothing gets rejected.
> 
>      include/vdso/limits.h:8:25: warning: overflow in conversion from 'int'
>      to 'short int' changes value from '2147483647' to '-1' [-Woverflow]

Indeed.
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>

Thank you!

-- 
Köry Maincent, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com