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

[Kalle Valo <kvalo@codeaurora.org>]

Laura Abbott <labbott@redhat.com> writes:

> 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.

Ok, I'll queue this to v5.4.

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