wifi: cfg80211: wext: fix IGTK key ID off-by-one

[ Upstream commit c8d7f21 ]

The IGTK key ID must be 4 or 5, but the code checks against
key ID + 1, so must check against 5/6 rather than 4/5. Fix
that.

Reported-by: Jouni Malinen <j@w1.fi>
Fixes: 0864512 ("cfg80211: implement wext key handling")
Link: https://patch.msgid.link/20260209181220.362205-2-johannes@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: jmberg-intel

net/wireless/wext-compat.c

@@ -684,7 +684,7 @@ static int cfg80211_wext_siwencodeext(struct net_device *dev,
 
 	idx = erq->flags & IW_ENCODE_INDEX;
 	if (cipher == WLAN_CIPHER_SUITE_AES_CMAC) {
-		if (idx < 4 || idx > 5) {
+		if (idx < 5 || idx > 6) {
 			idx = wdev->wext.default_mgmt_key;
 			if (idx < 0)
 				return -EINVAL;