tty: ipwireless: Fix potential NULL pointer dereference

There is a potential NULL pointer dereference in case
alloc_ctrl_packet() fails and returns NULL.

Fixes: 099dc4fb ("ipwireless: driver for PC Card 3G/UMTS modem")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/ipwireless/hardware.c

@@ -1516,6 +1516,8 @@ static void ipw_send_setup_packet(struct ipw_hardware *hw)
 			sizeof(struct ipw_setup_get_version_query_packet),
 			ADDR_SETUP_PROT, TL_PROTOCOLID_SETUP,
 			TL_SETUP_SIGNO_GET_VERSION_QRY);
+	if (!ver_packet)
+		return;
 	ver_packet->header.length = sizeof(struct tl_setup_get_version_qry);
 
 	/*