[PATCH 4.4 21/39] net: wireless: nl80211: fix out-of-bounds access in nl80211_del_key()

[Greg Kroah-Hartman]

From: Anant Thazhemadam <anant.thazhemadam@xxxxxxxxx>

commit 3dc289f8f139997f4e9d3cfccf8738f20d23e47b upstream.

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.

Cc: stable@xxxxxxxxxxxxxxx
Reported-by: syzbot+b1bb342d1d097516cbda@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: syzbot+b1bb342d1d097516cbda@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@xxxxxxxxx>
Link: https://lore.kernel.org/r/20201007035401.9522-1-anant.thazhemadam@xxxxxxxxx
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/wireless/nl80211.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3101,6 +3101,9 @@ static int nl80211_del_key(struct sk_buf
 	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]);