Subject: Re: [PATCH] mwl8k: Avoid memcpy() over-reading of ETH_SS_STATS

From: Andrew Lunn <[email-masked]>
Date: Wed, 16 Jun 2021 21:58:09 +0200

On Wed, Jun 16, 2021 at 12:52:42PM -0700, Kees Cook wrote:
> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> field bounds checking for memcpy(), memmove(), and memset(), avoid
> intentionally reading across neighboring array fields. Use the
> sub-structure address directly.
> 
> Signed-off-by: Kees Cook <[email-masked]>
> ---
>  drivers/net/wireless/marvell/mwl8k.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/marvell/mwl8k.c b/drivers/net/wireless/marvell/mwl8k.c
> index 84b32a5f01ee..3bf6571f4149 100644
> --- a/drivers/net/wireless/marvell/mwl8k.c
> +++ b/drivers/net/wireless/marvell/mwl8k.c
> @@ -4552,7 +4552,7 @@ static int mwl8k_cmd_update_stadb_add(struct ieee80211_hw *hw,
>  	else
>  		rates = sta->supp_rates[NL80211_BAND_5GHZ] << 5;
>  	legacy_rate_mask_to_array(p->legacy_rates, rates);
> -	memcpy(p->ht_rates, sta->ht_cap.mcs.rx_mask, 16);
> +	memcpy(p->ht_rates, &sta->ht_cap.mcs, 16);
>  	p->interop = 1;
>  	p->amsdu_enabled = 0;
>  
> @@ -5034,7 +5034,7 @@ mwl8k_bss_info_changed_sta(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
>  			ap_legacy_rates =
>  				ap->supp_rates[NL80211_BAND_5GHZ] << 5;
>  		}
> -		memcpy(ap_mcs_rates, ap->ht_cap.mcs.rx_mask, 16);
> +		memcpy(ap_mcs_rates, &ap->ht_cap.mcs, 16);
>  
>  		rcu_read_unlock();

This does not appear to have anything to do with ETH_SS_STATS which is
what the Subject: says.

     Andrew