[PROBLEM] selftests/bpf/progs/test_tunnel_kern.c: 678: 41-47: ERROR: application of sizeof to pointer

[PROBLEM] selftests/bpf/progs/test_tunnel_kern.c: 678: 41-47: ERROR: application of sizeof to pointer

[Mirsad Todorovac]

Hi, all!

In the linux-next tree, next-20241108, coccinelle found an error.

In the line 617, ret = bpf_skb_set_tunnel_opt(skb, gopt, sizeof(local_gopt));
In the line 678, ret = bpf_skb_set_tunnel_opt(skb, gopt, sizeof(gopt));

when

 592         struct local_geneve_opt local_gopt;
 593         struct geneve_opt *gopt = (struct geneve_opt *) &local_gopt;

and

 652         struct local_geneve_opt local_gopt;
 653         struct geneve_opt *gopt = (struct geneve_opt *) &local_gopt;

So, in all other call to bpf_skb_set_tunnel_opt(), the third parameter is the size of
the  struct, not the size of the pointer:

./tools/testing/selftests/bpf/progs/test_tunnel_kern.c:193:	ret = bpf_skb_set_tunnel_opt(skb, &md, sizeof(md));
./tools/testing/selftests/bpf/progs/test_tunnel_kern.c:273:	ret = bpf_skb_set_tunnel_opt(skb, &md, sizeof(md));
./tools/testing/selftests/bpf/progs/test_tunnel_kern.c:349:	ret = bpf_skb_set_tunnel_opt(skb, &md, sizeof(md));
./tools/testing/selftests/bpf/progs/test_tunnel_kern.c:388:	ret = bpf_skb_set_tunnel_opt(skb, &md, sizeof(md));
./tools/testing/selftests/bpf/progs/test_tunnel_kern.c:617:	ret = bpf_skb_set_tunnel_opt(skb, gopt, sizeof(local_gopt));
./tools/testing/selftests/bpf/progs/test_tunnel_kern.c:678:	ret = bpf_skb_set_tunnel_opt(skb, gopt, sizeof(gopt));



===========================================

 587 SEC("tc")
 588 int geneve_set_tunnel(struct __sk_buff *skb)
 589 {
 590         int ret;
 591         struct bpf_tunnel_key key;
 592         struct local_geneve_opt local_gopt;
 593         struct geneve_opt *gopt = (struct geneve_opt *) &local_gopt;
 594 
 595         __builtin_memset(&key, 0x0, sizeof(key));
 596         key.remote_ipv4 = 0xac100164; /* 172.16.1.100 */
 597         key.tunnel_id = 2;
 598         key.tunnel_tos = 0;
 599         key.tunnel_ttl = 64;
 600 
 601         __builtin_memset(gopt, 0x0, sizeof(local_gopt));
 602         gopt->opt_class = bpf_htons(0x102); /* Open Virtual Networking (OVN) */
 603         gopt->type = 0x08;
 604         gopt->r1 = 0;
 605         gopt->r2 = 0;
 606         gopt->r3 = 0;
 607         gopt->length = 2; /* 4-byte multiple */
 608         *(int *) &gopt->opt_data = bpf_htonl(0xdeadbeef);
 609 
 610         ret = bpf_skb_set_tunnel_key(skb, &key, sizeof(key),
 611                                      BPF_F_ZERO_CSUM_TX);
 612         if (ret < 0) {
 613                 log_err(ret);
 614                 return TC_ACT_SHOT;
 615         }
 616 
 617 →       ret = bpf_skb_set_tunnel_opt(skb, gopt, sizeof(local_gopt));
 618         if (ret < 0) {
 619                 log_err(ret);
 620                 return TC_ACT_SHOT;
 621         }
 622 
 623         return TC_ACT_OK;
 624 }

 648 SEC("tc")
 649 int ip6geneve_set_tunnel(struct __sk_buff *skb)
 650 {
 651         struct bpf_tunnel_key key;
 652         struct local_geneve_opt local_gopt;
 653         struct geneve_opt *gopt = (struct geneve_opt *) &local_gopt;
 654         int ret;
 655 
 656         __builtin_memset(&key, 0x0, sizeof(key));
 657         key.remote_ipv6[3] = bpf_htonl(0x11); /* ::11 */
 658         key.tunnel_id = 22;
 659         key.tunnel_tos = 0;
 660         key.tunnel_ttl = 64;
 661 
 662         ret = bpf_skb_set_tunnel_key(skb, &key, sizeof(key),
 663                                      BPF_F_TUNINFO_IPV6);
 664         if (ret < 0) {
 665                 log_err(ret);
 666                 return TC_ACT_SHOT;
 667         }
 668 
 669         __builtin_memset(gopt, 0x0, sizeof(local_gopt));
 670         gopt->opt_class = bpf_htons(0x102); /* Open Virtual Networking (OVN) */
 671         gopt->type = 0x08;
 672         gopt->r1 = 0;
 673         gopt->r2 = 0;
 674         gopt->r3 = 0;
 675         gopt->length = 2; /* 4-byte multiple */
 676         *(int *) &gopt->opt_data = bpf_htonl(0xfeedbeef);
 677 
 678  →      ret = bpf_skb_set_tunnel_opt(skb, gopt, sizeof(gopt));
 679         if (ret < 0) {
 680                 log_err(ret);
 681                 return TC_ACT_SHOT;
 682         }
 683 
 684         return TC_ACT_OK;
 685 }

SOLUTION:

Fixes: 5ddafcc377f98 ("selftests/bpf: Fix a few tests for GCC related warnings.")

------------------
diff --git a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
index 32127f1cd687..b53d367451b2 100644
--- a/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_tunnel_kern.c
@@ -675,7 +675,7 @@ int ip6geneve_set_tunnel(struct __sk_buff *skb)
        gopt->length = 2; /* 4-byte multiple */
        *(int *) &gopt->opt_data = bpf_htonl(0xfeedbeef);
 
-       ret = bpf_skb_set_tunnel_opt(skb, gopt, sizeof(gopt));
+       ret = bpf_skb_set_tunnel_opt(skb, gopt, sizeof(local_gopt));
        if (ret < 0) {
                log_err(ret);
                return TC_ACT_SHOT;
--

Best regards,
MT