staging: wilc1000: potential corruption in wilc_parse_join_bss_param()

The "rates_len" value needs to be capped so that the memcpy() doesn't
copy beyond the end of the array.

Fixes: c5c77ba1 ("staging: wilc1000: Add SDIO/SPI 802.11 driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Adham Abozaeid <adham.abozaeid@microchip.com>
Link: https://lore.kernel.org/r/20191017091832.GB31278@mwandaSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/wilc_hif.c

@@ -479,6 +479,8 @@ void *wilc_parse_join_bss_param(struct cfg80211_bss *bss,
 	rates_ie = cfg80211_find_ie(WLAN_EID_SUPP_RATES, ies->data, ies->len);
 	if (rates_ie) {
 		rates_len = rates_ie[1];
+		if (rates_len > WILC_MAX_RATES_SUPPORTED)
+			rates_len = WILC_MAX_RATES_SUPPORTED;
 		param->supp_rates[0] = rates_len;
 		memcpy(&param->supp_rates[1], rates_ie + 2, rates_len);
 	}