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

From: Laura Abbott
Date: Sat Oct 19 2019 - 15:03:00 EST


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