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From:   Laura Abbott <labbott@redhat.com>
To:     Ping-Ke Shih <pkshih@realtek.com>,
        Kalle Valo <kvalo@codeaurora.org>
Cc:     Laura Abbott <labbott@redhat.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>
Subject: [PATCH v2] rtlwifi: Fix potential overflow on P2P code
Date:   Fri, 18 Oct 2019 07:43:21 -0400
Message-Id: <20191018114321.13131-1-labbott@redhat.com>
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Sender: linux-wireless-owner@vger.kernel.org
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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;
+
 			}
 			noa_index = ie[3];
 			if (rtlpriv->psc.p2p_ps_info.p2p_ps_mode ==
-- 
2.21.0