Re: [PATCH v2] rtlwifi: Fix potential overflow on P2P code

[Laura Abbott]

On 10/19/19 6:51 AM, Kalle Valo wrote:
> Laura Abbott <labbott@xxxxxxxxxx> writes:
>
> > Nicolas Waisman noticed that even though noa_len is checked for
> > a compatible length it's still possible to overrun the buffers
> > of p2pinfo since there's no check on the upper bound of noa_num.
> > Bound noa_num against P2P_MAX_NOA_NUM.
> >
> > Reported-by: Nicolas Waisman <nico@xxxxxxxxxx>
> > Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
> > ---
> > v2: Use P2P_MAX_NOA_NUM instead of erroring out.
> > ---
> >   drivers/net/wireless/realtek/rtlwifi/ps.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/net/wireless/realtek/rtlwifi/ps.c b/drivers/net/wireless/realtek/rtlwifi/ps.c
> > index 70f04c2f5b17..fff8dda14023 100644
> > --- a/drivers/net/wireless/realtek/rtlwifi/ps.c
> > +++ b/drivers/net/wireless/realtek/rtlwifi/ps.c
> > @@ -754,6 +754,9 @@ static void rtl_p2p_noa_ie(struct ieee80211_hw *hw, void *data,
> >   				return;
> >   			} else {
> >   				noa_num = (noa_len - 2) / 13;
> > +				if (noa_num > P2P_MAX_NOA_NUM)
> > +					noa_num = P2P_MAX_NOA_NUM;
> > +
> >   			}
> >   			noa_index = ie[3];
> >   			if (rtlpriv->psc.p2p_ps_info.p2p_ps_mode ==
> > @@ -848,6 +851,9 @@ static void rtl_p2p_action_ie(struct ieee80211_hw *hw, void *data,
> >   				return;
> >   			} else {
> >   				noa_num = (noa_len - 2) / 13;
> > +				if (noa_num > P2P_MAX_NOA_NUM)
> > +					noa_num = P2P_MAX_NOA_NUM;
>
> IMHO using min() would be cleaner, but I'm fine with this as well. Up to
> you.

I believe the intention is to re-write this anyway so I'd prefer to
just get this in given the uptick this issue seems to have gotten.

Thanks,
Laura