wifi: cw1200: Avoid processing an invalid TIM IE

While converting struct ieee80211_tim_ie::virtual_map to be a flexible
array it was observed that the TIM IE processing in cw1200_rx_cb()
could potentially process a malformed IE in a manner that could result
in a buffer over-read. Add logic to verify that the TIM IE length is
large enough to hold a valid TIM payload before processing it.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230831-ieee80211_tim_ie-v3-1-e10ff584ab5d@quicinc.com

drivers/net/wireless/st/cw1200/txrx.c

@@ -1166,7 +1166,7 @@ void cw1200_rx_cb(struct cw1200_common *priv,
 		size_t ies_len = skb->len - (ies - (u8 *)(skb->data));
 
 		tim_ie = cfg80211_find_ie(WLAN_EID_TIM, ies, ies_len);
-		if (tim_ie) {
+		if (tim_ie && tim_ie[1] >= sizeof(struct ieee80211_tim_ie)) {
 			struct ieee80211_tim_ie *tim =
 				(struct ieee80211_tim_ie *)&tim_ie[2];