qcacmn: Fix Uninitialized byte sent to FW in wmi_unified_cmd_send

In wmi_unified_cmd_send, the skb head is pushed by size of WMI_CMD_HDR
and then the commandId is initialized in the header. However 1 byte of
reserved memory in the WMI_CMD_HDR is not initialized and is sent to
the FW as it is and this might lead to exposure of 1 byte of kernel
memory to FW.

Initialize the WMI_CMD_HDR to zero once the skb head is pushed and
then set the commandId in the header.

Change-Id: I89fd5401105cd9c61674a63aac5aa88fb20cc41a
CRs-Fixed: 2257688

wmi/src/wmi_unified.c

@@ -1387,6 +1387,7 @@ QDF_STATUS wmi_unified_cmd_send(wmi_unified_t wmi_handle, wmi_buf_t buf,
 		return QDF_STATUS_E_NOMEM;
 	}
 
+	qdf_mem_zero(qdf_nbuf_data(buf), sizeof(WMI_CMD_HDR));
 	WMI_SET_FIELD(qdf_nbuf_data(buf), WMI_CMD_HDR, COMMANDID, cmd_id);
 
 	qdf_atomic_inc(&wmi_handle->pending_cmds);