[PATCH] rtlwifi: Fix potential overflow on P2P code

[Laura Abbott <labbott@redhat.com>]

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.
Bounds check noa_num against P2P_MAX_NOA_NUM.

Reported-by: Nicolas Waisman <nico@semmle.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
---
Compile tested only as this was reported to the security list.
---
 drivers/net/wireless/realtek/rtlwifi/ps.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtlwifi/ps.c b/drivers/net/wireless/realtek/rtlwifi/ps.c
index 70f04c2f5b17..c5cff598383d 100644
--- a/drivers/net/wireless/realtek/rtlwifi/ps.c
+++ b/drivers/net/wireless/realtek/rtlwifi/ps.c
@@ -754,6 +754,13 @@ 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) {
+					RT_TRACE(rtlpriv, COMP_INIT, DBG_LOUD,
+						 "P2P notice of absence: invalid noa_num.%d\n",
+						 noa_num);
+					return;
+				}
+
 			}
 			noa_index = ie[3];
 			if (rtlpriv->psc.p2p_ps_info.p2p_ps_mode ==
@@ -848,6 +855,13 @@ 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) {
+					RT_TRACE(rtlpriv, COMP_FW, DBG_LOUD,
+						 "P2P notice of absence: invalid noa_len.%d\n",
+						 noa_len);
+					return;
+
+				}
 			}
 			noa_index = ie[3];
 			if (rtlpriv->psc.p2p_ps_info.p2p_ps_mode ==
-- 
2.21.0