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Subject: Re: [PATCH v2] rtlwifi: Fix potential overflow on P2P code
To:     Kalle Valo <kvalo@codeaurora.org>
Cc:     Ping-Ke Shih <pkshih@realtek.com>,
        "David S . Miller" <davem@davemloft.net>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Nicolas Waisman <nico@semmle.com>
References: <20191018114321.13131-1-labbott@redhat.com>
 <871rv9xb2l.fsf@kamboji.qca.qualcomm.com>
From:   Laura Abbott <labbott@redhat.com>
Message-ID: <51b732bf-4575-d7d1-daff-ec1c2171a303@redhat.com>
Date:   Sat, 19 Oct 2019 15:02:47 -0400
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On 10/19/19 6:51 AM, Kalle Valo wrote:
> Laura Abbott <labbott@redhat.com> writes:
>=20
>> 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/wir=
eless/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,
>>   =09=09=09=09return;
>>   =09=09=09} else {
>>   =09=09=09=09noa_num =3D (noa_len - 2) / 13;
>> +=09=09=09=09if (noa_num > P2P_MAX_NOA_NUM)
>> +=09=09=09=09=09noa_num =3D P2P_MAX_NOA_NUM;
>> +
>>   =09=09=09}
>>   =09=09=09noa_index =3D ie[3];
>>   =09=09=09if (rtlpriv->psc.p2p_ps_info.p2p_ps_mode =3D=3D
>> @@ -848,6 +851,9 @@ static void rtl_p2p_action_ie(struct ieee80211_hw *h=
w, void *data,
>>   =09=09=09=09return;
>>   =09=09=09} else {
>>   =09=09=09=09noa_num =3D (noa_len - 2) / 13;
>> +=09=09=09=09if (noa_num > P2P_MAX_NOA_NUM)
>> +=09=09=09=09=09noa_num =3D P2P_MAX_NOA_NUM;
>=20
> IMHO using min() would be cleaner, but I'm fine with this as well. Up to
> you.
>=20

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