selftests/bpf: add another gso_segs access

Use BPF_REG_1 for source and destination of gso_segs read,
to exercise "bpf: fix access to skb_shared_info->gso_segs" fix.

Signed-off-by: Eric Dumazet <[email protected]>
Suggested-by: Stanislav Fomichev <[email protected]>
Signed-off-by: Alexei Starovoitov <[email protected]>

diff --git a/tools/testing/selftests/bpf/verifier/ctx_skb.c b/tools/testing/selftests/bpf/verifier/ctx_skb.c
index b0fda2877119c4af08277bd0f329f238c193313c..d438193804b212ffa80c94be47e8c1aca392181e 100644 (file)
--- a/tools/testing/selftests/bpf/verifier/ctx_skb.c
+++ b/tools/testing/selftests/bpf/verifier/ctx_skb.c
@@ -974,6 +974,17 @@
        .result = ACCEPT,
        .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
 },
+{
+       "read gso_segs from CGROUP_SKB",
+       .insns = {
+       BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_1,
+                   offsetof(struct __sk_buff, gso_segs)),
+       BPF_MOV64_IMM(BPF_REG_0, 0),
+       BPF_EXIT_INSN(),
+       },
+       .result = ACCEPT,
+       .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+},
 {
        "write gso_segs from CGROUP_SKB",
        .insns = {