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

[Laura Abbott <labbott@redhat.com>]

On 10/19/19 6:51 AM, Kalle Valo wrote:
> Laura Abbott <labbott@redhat.com> 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@semmle.com>
>> Signed-off-by: Laura Abbott <labbott@redhat.com>
>> ---
>> 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