[PATCH 1/1] UBUNTU: SAUCE: rtlwifi: Fix potential overflow on P2P code

[Tyler Hicks]

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 using the minimum of the
two.

CVE-2019-17666

Reported-by: Nicolas Waisman <nico at semmle.com>
Suggested-by: Ping-Ke Shih <pkshih at realtek.com>
[tyhicks: Reuse nearly all of a commit message written by Laura Abbott]
Signed-off-by: Tyler Hicks <tyhicks at canonical.com>
---
 drivers/net/wireless/realtek/rtlwifi/ps.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/ps.c b/drivers/net/wireless/realtek/rtlwifi/ps.c
index 70f04c2f5b17..3b79c25bc376 100644
--- a/drivers/net/wireless/realtek/rtlwifi/ps.c
+++ b/drivers/net/wireless/realtek/rtlwifi/ps.c
@@ -753,7 +753,8 @@ static void rtl_p2p_noa_ie(struct ieee80211_hw *hw, void *data,
 					 noa_len);
 				return;
 			} else {
-				noa_num = (noa_len - 2) / 13;
+				noa_num = min((noa_len - 2) / 13,
+					      P2P_MAX_NOA_NUM);
 			}
 			noa_index = ie[3];
 			if (rtlpriv->psc.p2p_ps_info.p2p_ps_mode ==
@@ -847,7 +848,8 @@ static void rtl_p2p_action_ie(struct ieee80211_hw *hw, void *data,
 					 noa_len);
 				return;
 			} else {
-				noa_num = (noa_len - 2) / 13;
+				noa_num = min((noa_len - 2) / 13,
+					      P2P_MAX_NOA_NUM);
 			}
 			noa_index = ie[3];
 			if (rtlpriv->psc.p2p_ps_info.p2p_ps_mode ==
-- 
2.17.1