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 15:52, Nicolai Buchwitz wrote:
> A provider index of 0xFFFFFFFF picks a provider on hardware that has
> none. phc_index is an int where -1 means no PHC, and the u32 from user
> space ends up as -1, so the two match.
> 
> TSINFO_GET uses -1 for "no provider requested" and answers with the
> default provider instead of an error.
> 
> Reject the value in the netlink policy, which covers every comparison
> site.
> 
> Fixes: b9e3f7dc9ed9 ("net: ethtool: tsinfo: Enhance tsinfo to support several hwtstamp by net topology")
> Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
> ---
> NLA_POLICY_MAX does not fit here, .max in struct nla_policy is s16.
> 
>   net/ethtool/ts.h | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/net/ethtool/ts.h b/net/ethtool/ts.h
> index d901a879a671..ab9805308353 100644
> --- a/net/ethtool/ts.h
> +++ b/net/ethtool/ts.h
> @@ -5,9 +5,15 @@
>   
>   #include "netlink.h"
>   
> +/* phc_index is an int and -1 means no PHC, so keep the request non-negative */
> +static const struct netlink_range_validation ethnl_ts_prov_index_range = {
> +	.max = INT_MAX,
> +};
> +
>   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),

> base-commit: 11536ee3d3e0b1bd35b6f3f8df55a6053eb0c71d

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