selftests/bpf: Fix misaligned accesses in xdp and xdp_bpf2bpf tests

Similar to previous patch, just copy over necessary struct into local
stack variable before checking its fields.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-14-andrii@kernel.org

Author: anakryiko

tools/testing/selftests/bpf/prog_tests/xdp.c

@@ -11,8 +11,8 @@ void test_xdp(void)
 	const char *file = "./test_xdp.o";
 	struct bpf_object *obj;
 	char buf[128];
-	struct ipv6hdr *iph6 = (void *)buf + sizeof(struct ethhdr);
-	struct iphdr *iph = (void *)buf + sizeof(struct ethhdr);
+	struct ipv6hdr iph6;
+	struct iphdr iph;
 	__u32 duration, retval, size;
 	int err, prog_fd, map_fd;
 
@@ -28,16 +28,17 @@ void test_xdp(void)
 
 	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
 				buf, &size, &retval, &duration);
-
+	memcpy(&iph, buf + sizeof(struct ethhdr), sizeof(iph));
 	CHECK(err || retval != XDP_TX || size != 74 ||
-	      iph->protocol != IPPROTO_IPIP, "ipv4",
+	      iph.protocol != IPPROTO_IPIP, "ipv4",
 	      "err %d errno %d retval %d size %d\n",
 	      err, errno, retval, size);
 
 	err = bpf_prog_test_run(prog_fd, 1, &pkt_v6, sizeof(pkt_v6),
 				buf, &size, &retval, &duration);
+	memcpy(&iph6, buf + sizeof(struct ethhdr), sizeof(iph6));
 	CHECK(err || retval != XDP_TX || size != 114 ||
-	      iph6->nexthdr != IPPROTO_IPV6, "ipv6",
+	      iph6.nexthdr != IPPROTO_IPV6, "ipv6",
 	      "err %d errno %d retval %d size %d\n",
 	      err, errno, retval, size);
 out:

tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c

@@ -42,7 +42,7 @@ void test_xdp_bpf2bpf(void)
 	char buf[128];
 	int err, pkt_fd, map_fd;
 	bool passed = false;
-	struct iphdr *iph = (void *)buf + sizeof(struct ethhdr);
+	struct iphdr iph;
 	struct iptnl_info value4 = {.family = AF_INET};
 	struct test_xdp *pkt_skel = NULL;
 	struct test_xdp_bpf2bpf *ftrace_skel = NULL;
@@ -93,9 +93,9 @@ void test_xdp_bpf2bpf(void)
 	/* Run test program */
 	err = bpf_prog_test_run(pkt_fd, 1, &pkt_v4, sizeof(pkt_v4),
 				buf, &size, &retval, &duration);
-
+	memcpy(&iph, buf + sizeof(struct ethhdr), sizeof(iph));
 	if (CHECK(err || retval != XDP_TX || size != 74 ||
-		  iph->protocol != IPPROTO_IPIP, "ipv4",
+		  iph.protocol != IPPROTO_IPIP, "ipv4",
 		  "err %d errno %d retval %d size %d\n",
 		  err, errno, retval, size))
 		goto out;