brcmfmac: add length checks in scheduled scan result handler

commit 4835f37e upstream.

Assure the event data buffer is long enough to hold the array
of netinfo items and that SSID length does not exceed the maximum
of 32 characters as per 802.11 spec.
Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
[bwh: Backported to 4.9:
 - Move the assignment to "data" along with the assignment to "netinfo_start"
   that depends on it
 - Adjust context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c

@@ -3220,6 +3220,7 @@ brcmf_notify_sched_scan_results(struct brcmf_if *ifp,
 	struct brcmf_pno_scanresults_le *pfn_result;
 	u32 result_count;
 	u32 status;
+	u32 datalen;
 
 	brcmf_dbg(SCAN, "Enter\n");
 
@@ -3245,6 +3246,14 @@ brcmf_notify_sched_scan_results(struct brcmf_if *ifp,
 	if (result_count > 0) {
 		int i;
 
+		data += sizeof(struct brcmf_pno_scanresults_le);
+		netinfo_start = (struct brcmf_pno_net_info_le *)data;
+		datalen = e->datalen - ((void *)netinfo_start - (void *)pfn_result);
+		if (datalen < result_count * sizeof(*netinfo)) {
+			brcmf_err("insufficient event data\n");
+			goto out_err;
+		}
+
 		request = kzalloc(sizeof(*request), GFP_KERNEL);
 		ssid = kcalloc(result_count, sizeof(*ssid), GFP_KERNEL);
 		channel = kcalloc(result_count, sizeof(*channel), GFP_KERNEL);
@@ -3254,9 +3263,6 @@ brcmf_notify_sched_scan_results(struct brcmf_if *ifp,
 		}
 
 		request->wiphy = wiphy;
-		data += sizeof(struct brcmf_pno_scanresults_le);
-		netinfo_start = (struct brcmf_pno_net_info_le *)data;
-
 		for (i = 0; i < result_count; i++) {
 			netinfo = &netinfo_start[i];
 			if (!netinfo) {
@@ -3266,6 +3272,8 @@ brcmf_notify_sched_scan_results(struct brcmf_if *ifp,
 				goto out_err;
 			}
 
+			if (netinfo->SSID_len > IEEE80211_MAX_SSID_LEN)
+				netinfo->SSID_len = IEEE80211_MAX_SSID_LEN;
 			brcmf_dbg(SCAN, "SSID:%s Channel:%d\n",
 				  netinfo->SSID, netinfo->channel);
 			memcpy(ssid[i].ssid, netinfo->SSID, netinfo->SSID_len);