wifi: wilc1000: validate length of IEEE80211_P2P_ATTR_OPER_CHANNEL attribute

Validate that the IEEE80211_P2P_ATTR_OPER_CHANNEL attribute contains
enough space for a 'struct struct wilc_attr_oper_ch'. If the attribute is
too small then it triggers an out-of-bounds write later in the function.
Signed-off-by: Phil Turnbull <philipturnbull@github.com>
Tested-by: Ajay Kathat <ajay.kathat@microchip.com>
Acked-by: Ajay Kathat <ajay.kathat@microchip.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20221123153543.8568-3-philipturnbull@github.com

drivers/net/wireless/microchip/wilc1000/cfg80211.c

@@ -959,14 +959,24 @@ static inline void wilc_wfi_cfg_parse_ch_attr(u8 *buf, u32 len, u8 sta_ch)
 		return;
 
 	while (index + sizeof(*e) <= len) {
+		u16 attr_size;
+
 		e = (struct wilc_attr_entry *)&buf[index];
+		attr_size = le16_to_cpu(e->attr_len);
+
+		if (index + sizeof(*e) + attr_size > len)
+			return;
+
 		if (e->attr_type == IEEE80211_P2P_ATTR_CHANNEL_LIST)
 			ch_list_idx = index;
-		else if (e->attr_type == IEEE80211_P2P_ATTR_OPER_CHANNEL)
+		else if (e->attr_type == IEEE80211_P2P_ATTR_OPER_CHANNEL &&
+			 attr_size == (sizeof(struct wilc_attr_oper_ch) - sizeof(*e)))
 			op_ch_idx = index;
+
 		if (ch_list_idx && op_ch_idx)
 			break;
-		index += le16_to_cpu(e->attr_len) + sizeof(*e);
+
+		index += sizeof(*e) + attr_size;
 	}
 
 	if (ch_list_idx) {