wifi: wilc1000: validate length of IEEE80211_P2P_ATTR_CHANNEL_LIST attribute

Validate that the IEEE80211_P2P_ATTR_CHANNEL_LIST attribute contains
enough space for a 'struct wilc_attr_oper_ch'. If the attribute is too
small then it can trigger an out-of-bounds write later in the function.

'struct wilc_attr_oper_ch' is variable sized so also check 'attr_len'
does not extend beyond the end of 'buf'.
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/20221123153543.8568-4-philipturnbull@github.com

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

@@ -967,7 +967,8 @@ static inline void wilc_wfi_cfg_parse_ch_attr(u8 *buf, u32 len, u8 sta_ch)
 		if (index + sizeof(*e) + attr_size > len)
 			return;
 
-		if (e->attr_type == IEEE80211_P2P_ATTR_CHANNEL_LIST)
+		if (e->attr_type == IEEE80211_P2P_ATTR_CHANNEL_LIST &&
+		    attr_size >= (sizeof(struct wilc_attr_ch_list) - sizeof(*e)))
 			ch_list_idx = index;
 		else if (e->attr_type == IEEE80211_P2P_ATTR_OPER_CHANNEL &&
 			 attr_size == (sizeof(struct wilc_attr_oper_ch) - sizeof(*e)))