netdev - [PATCH] net: wireless: nl80211: fix out-of-bounds access in nl80211_del

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Date:   Wed,  7 Oct 2020 09:24:01 +0530
From:   Anant Thazhemadam <anant.thazhemadam@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        Anant Thazhemadam <anant.thazhemadam@...il.com>,
        syzbot+b1bb342d1d097516cbda@...kaller.appspotmail.com,
        Johannes Berg <johannes@...solutions.net>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] net: wireless: nl80211: fix out-of-bounds access in nl80211_del_key()

In nl80211_parse_key(), key.idx is first initialized as -1. 
If this value of key.idx remains unmodified and gets returned, and
nl80211_key_allowed() also returns 0, then rdev_del_key() gets called 
with key.idx = -1.
This causes an out-of-bounds array access.

Handle this issue by checking if the value of key.idx after
nl80211_parse_key() is called and return -EINVAL if key.idx < 0.

Reported-by: syzbot+b1bb342d1d097516cbda@...kaller.appspotmail.com
Tested-by: syzbot+b1bb342d1d097516cbda@...kaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@...il.com>
---
 net/wireless/nl80211.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 2c9e9a2d1688..7fd45f6ddb05 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -4172,6 +4172,9 @@ static int nl80211_del_key(struct sk_buff *skb, struct genl_info *info)
 	if (err)
 		return err;
 
+	if (key.idx < 0)
+		return -EINVAL;
+
 	if (info->attrs[NL80211_ATTR_MAC])
 		mac_addr = nla_data(info->attrs[NL80211_ATTR_MAC]);
 
-- 
2.25.1