Re: [Intel-wired-lan] [PATCH net] ice: fix theoretical out-of-bounds access in ethtool link modes

[Przemek Kitszel <przemyslaw.kitszel@intel.com>]

On 11/30/23 17:58, Michal Schmidt wrote:
> To map phy types reported by the hardware to ethtool link mode bits,
> ice uses two lookup tables (phy_type_low_lkup, phy_type_high_lkup).
> The "low" table has 64 elements to cover every possible bit the hardware
> may report, but the "high" table has only 13. If the hardware reports a
> higher bit in phy_types_high, the driver would access memory beyond the
> lookup table's end.
> 
> Instead of iterating through all 64 bits of phy_types_{low,high}, use
> the sizes of the respective lookup tables.
> 
> Fixes: 9136e1f1e5c3 ("ice: refactor PHY type to ethtool link mode")
> Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
> ---
>   drivers/net/ethernet/intel/ice/ice_ethtool.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_ethtool.c b/drivers/net/ethernet/intel/ice/ice_ethtool.c
> index a34083567e6f..bde9bc74f928 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ethtool.c
> +++ b/drivers/net/ethernet/intel/ice/ice_ethtool.c
> @@ -1850,14 +1850,14 @@ ice_phy_type_to_ethtool(struct net_device *netdev,
>   	linkmode_zero(ks->link_modes.supported);
>   	linkmode_zero(ks->link_modes.advertising);
>   
> -	for (i = 0; i < BITS_PER_TYPE(u64); i++) {
> +	for (i = 0; i < ARRAY_SIZE(phy_type_low_lkup); i++) {
>   		if (phy_types_low & BIT_ULL(i))
>   			ice_linkmode_set_bit(&phy_type_low_lkup[i], ks,
>   					     req_speeds, advert_phy_type_lo,
>   					     i);
>   	}
>   
> -	for (i = 0; i < BITS_PER_TYPE(u64); i++) {
> +	for (i = 0; i < ARRAY_SIZE(phy_type_high_lkup); i++) {
>   		if (phy_types_high & BIT_ULL(i))
>   			ice_linkmode_set_bit(&phy_type_high_lkup[i], ks,
>   					     req_speeds, advert_phy_type_hi,

I guess that that "HW reported" number really goes through the FW in
some way, so one could indeed spoil that in some way,
what makes sense to target it at -net.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
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