[bpf-next PATCH v2 2/4] bpf: selftests, verifier case for non null pointer check branch taken

[John Fastabend]

When we have pointer type that is known to be non-null and comparing
against zero we only follow the non-null branch. This adds tests to
cover this case for reference tracking. Also add the other case when
comparison against a non-zero value and ensure we still fail with
unreleased reference.

Signed-off-by: John Fastabend <john.fastab...@gmail.com>
---
 .../testing/selftests/bpf/verifier/ref_tracking.c  |   33 ++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/ref_tracking.c 
b/tools/testing/selftests/bpf/verifier/ref_tracking.c
index 604b461..056e027 100644
--- a/tools/testing/selftests/bpf/verifier/ref_tracking.c
+++ b/tools/testing/selftests/bpf/verifier/ref_tracking.c
@@ -821,3 +821,36 @@
        .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,
+},
+{
+       "reference tracking: branch tracking valid pointer value 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_JEQ, BPF_REG_6, 0, 4),
+       BPF_MOV64_IMM(BPF_REG_3, 0),
+       BPF_JMP_IMM(BPF_JEQ, BPF_REG_6, 1234, 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,
+       .errstr = "Unreleased reference",
+       .result = REJECT,
+},