qcacmn: Possible OOB read in process_fw_diag_event_data

API "fw_diag_data_event_handler" is the handler of an event
WMI_DIAG_DATA_CONTAINER_EVENTID comes from FW. Arguments of
this handler function come from FW.

If num_data may be less than size of(struct wlan_diag_data),
possible OOB while extracting event data.

Fix is to add a sanity check for num_data to avoid the OOB
read.

Change-Id: Ia2eb62dbaa154936bdb4ea34065657d441f12810
CRs-Fixed: 3001178

utils/fwlog/dbglog_host.c

@@ -1694,7 +1694,7 @@ process_fw_diag_event_data(uint8_t *datap, uint32_t num_data)
 	uint32_t diag_data_len; /* each fw diag payload */
 	struct wlan_diag_data *diag_data;
 
-	while (num_data > 0) {
+	while (num_data >= sizeof(struct wlan_diag_data)) {
 		diag_data = (struct wlan_diag_data *)datap;
 		diag_type = WLAN_DIAG_0_TYPE_GET(diag_data->word0);
 		diag_data_len = WLAN_DIAG_0_LEN_GET(diag_data->word0);