netdev - [bpf-next PATCH 2/4] bpf: selftests, verifier case for non null pointer check branch taken

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Date:   Mon, 18 May 2020 13:02:52 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     ast@...nel.org, daniel@...earbox.net
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        john.fastabend@...il.com
Subject: [bpf-next PATCH 2/4] bpf: selftests,
 verifier case for non null pointer check branch taken

When we have pointer type that is known to be non-null we only follow
the non-null branch. This adds tests to cover this case for reference
tracking.

Signed-off-by: John Fastabend <john.fastabend@...il.com>
---
 .../testing/selftests/bpf/verifier/ref_tracking.c  |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/ref_tracking.c b/tools/testing/selftests/bpf/verifier/ref_tracking.c
index 604b461..d8f7c04 100644
--- a/tools/testing/selftests/bpf/verifier/ref_tracking.c
+++ b/tools/testing/selftests/bpf/verifier/ref_tracking.c
@@ -821,3 +821,19 @@
 	.result = REJECT,
 	.errstr = "invalid mem access",
 },
+{
+	"reference tracking: branch tracking valid pointer null comparison",
+	.insns = {
+	BPF_SK_LOOKUP(sk_lookup_tcp),
+	BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+	BPF_MOV64_IMM(BPF_REG_3, 1),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_6, 0, 1),
+	BPF_MOV64_IMM(BPF_REG_3, 0),
+	BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 0, 2),
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+	BPF_EMIT_CALL(BPF_FUNC_sk_release),
+	BPF_EXIT_INSN(),
+	},
+	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
+	.result = ACCEPT,
+},