[bug report] mctp: Add route input to socket tests

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

Hello Jeremy Kerr,

Commit 8892c0490779 ("mctp: Add route input to socket tests") from
Oct 3, 2021 (linux-next), leads to the following Smatch static
checker warning:

	net/mctp/test/route-test.c:369 mctp_test_route_input_sk()
	warn: 'skb' was already freed. (line 365)

net/mctp/test/route-test.c
    344 static void mctp_test_route_input_sk(struct kunit *test)
    345 {
    346         const struct mctp_route_input_sk_test *params;
    347         struct sk_buff *skb, *skb2;
    348         struct mctp_test_route *rt;
    349         struct mctp_test_dev *dev;
    350         struct socket *sock;
    351         int rc;
    352 
    353         params = test->param_value;
    354 
    355         __mctp_route_test_init(test, &dev, &rt, &sock, MCTP_NET_ANY);
    356 
    357         skb = mctp_test_create_skb_data(&params->hdr, &params->type);
    358         KUNIT_ASSERT_NOT_ERR_OR_NULL(test, skb);
    359 
    360         mctp_test_skb_set_dev(skb, dev);
    361 
    362         rc = mctp_route_input(&rt->rt, skb);
                                               ^^^
skb freed here

    363 
    364         if (params->deliver) {
    365                 KUNIT_EXPECT_EQ(test, rc, 0);
    366 
    367                 skb2 = skb_recv_datagram(sock->sk, MSG_DONTWAIT, &rc);
    368                 KUNIT_EXPECT_NOT_ERR_OR_NULL(test, skb2);
--> 369                 KUNIT_EXPECT_EQ(test, skb->len, 1);
                                              ^^^^^^^^
I wonder if this was intended to be skb2->len?

    370 
    371                 skb_free_datagram(sock->sk, skb2);
    372 
    373         } else {
    374                 KUNIT_EXPECT_NE(test, rc, 0);
    375                 skb2 = skb_recv_datagram(sock->sk, MSG_DONTWAIT, &rc);
    376                 KUNIT_EXPECT_NULL(test, skb2);
    377         }
    378 
    379         __mctp_route_test_fini(test, dev, rt, sock);
    380 }

regards,
dan carpenter