[lvc-project] [PATCH v2] iwlegacy: 4965: fix possible out-of-bounds access in il4965_tx_cmd_build_rate()

[Fedor Pchelkin]

Hello,

On Sun, 27. Apr 08:39, Stanislaw Gruszka wrote:
> > diff --git a/drivers/net/wireless/intel/iwlegacy/4965-mac.c b/drivers/net/wireless/intel/iwlegacy/4965-mac.c
> > index 78dee8ccfebf..f60d9b9798c1 100644
> > --- a/drivers/net/wireless/intel/iwlegacy/4965-mac.c
> > +++ b/drivers/net/wireless/intel/iwlegacy/4965-mac.c
> > @@ -1572,7 +1572,7 @@ il4965_tx_cmd_build_rate(struct il_priv *il,
> >  	 */
> >  	rate_idx = info->control.rates[0].idx;
> >  	if ((info->control.rates[0].flags & IEEE80211_TX_RC_MCS) || rate_idx < 0
> > -	    || rate_idx > RATE_COUNT_LEGACY)
> > +	    || rate_idx >= RATE_COUNT_LEGACY)
> >  		rate_idx = rate_lowest_index(&il->bands[info->band], sta);
> 
> .. so looks the check is fine already and changing it will induce a bug
> for RATE_54M_INDEX.
> 
> Regards
> Stanislaw
> 
> >  	/* For 5 GHZ band, remap mac80211 rate indices into driver indices */
> >  	if (info->band == NL80211_BAND_5GHZ)

Here goes the fragment:

		rate_idx += IL_FIRST_OFDM_RATE;
	/* Get PLCP rate for tx_cmd->rate_n_flags */
	rate_plcp = il_rates[rate_idx].plcp;

> > -- 
> > 2.39.5 (Apple Git-154)
> > 

Looks like the proper checks should be added to address the 5GHZ case and
validate that the index won't exceed the array boundaries after being shifted
by IL_FIRST_OFDM_RATE.

--
Thanks,
Fedor