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 <edumazet@google.com>
Suggested-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/verifier/ctx_skb.c b/tools/testing/selftests/bpf/verifier/ctx_skb.c
index b0fda2877119..d438193804b2 100644
--- a/tools/testing/selftests/bpf/verifier/ctx_skb.c
+++ b/tools/testing/selftests/bpf/verifier/ctx_skb.c
@@ -975,6 +975,17 @@
         .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 = {
         BPF_MOV64_IMM(BPF_REG_0, 0),