[PATCH AUTOSEL 5.2 035/123] selftests/bpf: add another gso_segs access

[Sasha Levin]

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit be69483bf4f3abaaca5d5ba460dbb50239463552 ]

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@xxxxxxxxxx>
Suggested-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/verifier/ctx_skb.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/ctx_skb.c b/tools/testing/selftests/bpf/verifier/ctx_skb.c
index b0fda2877119c..d438193804b21 100644
--- 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 = {
-- 
2.20.1