wifi: mac80211: Fix HE capabilities element check

The element data length check did not account for the extra
octet used for the extension ID. Fix it.

Signed-off-by: Ilan Peer <[email protected]>
Signed-off-by: Miri Korenblit <[email protected]>
Link: https://patch.msgid.link/20250907115109.8da0012e2286.I8c0c69a0011f7153c13b365b14dfef48cfe7c3e3@changeid
Signed-off-by: Johannes Berg <[email protected]>

Author: ilanpeer2

net/mac80211/mlme.c

@@ -5725,7 +5725,7 @@ static u8 ieee80211_max_rx_chains(struct ieee80211_link_data *link,
 	he_cap_elem = cfg80211_find_ext_elem(WLAN_EID_EXT_HE_CAPABILITY,
 					     ies->data, ies->len);
 
-	if (!he_cap_elem || he_cap_elem->datalen < sizeof(*he_cap))
+	if (!he_cap_elem || he_cap_elem->datalen < sizeof(*he_cap) + 1)
 		return chains;
 
 	/* skip one byte ext_tag_id */