linux-kernel - [PATCH bpf-next 2/2] selftests/bpf: check null propagation only neither reg is PTR_TO_BTF

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Date:   Mon, 12 Dec 2022 12:15:47 +0800
From:   Hao Sun <sunhao.th@...il.com>
To:     bpf@...r.kernel.org
Cc:     ast@...nel.org, daniel@...earbox.net, john.fastabend@...il.com,
        andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org,
        yhs@...com, kpsingh@...nel.org, sdf@...gle.com, haoluo@...gle.com,
        jolsa@...nel.org, davem@...emloft.net,
        linux-kernel@...r.kernel.org, Hao Sun <sunhao.th@...il.com>
Subject: [PATCH bpf-next 2/2] selftests/bpf: check null propagation only neither reg is PTR_TO_BTF_ID

Verify that nullness information is not porpagated in the branches
of register to register JEQ and JNE operations if one of them is
PTR_TO_BTF_ID.

Signed-off-by: Hao Sun <sunhao.th@...il.com>
---
 .../bpf/verifier/jeq_infer_not_null.c         | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c b/tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c
index 67a1c07ead34..b2b215227d97 100644
--- a/tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c
+++ b/tools/testing/selftests/bpf/verifier/jeq_infer_not_null.c
@@ -172,3 +172,25 @@
 	.prog_type = BPF_PROG_TYPE_XDP,
 	.result = ACCEPT,
 },
+{
+	"jne/jeq infer not null, PTR_TO_MAP_OR_NULL unchanged with PTR_TO_BTF_ID reg",
+	.insns = {
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_ST_MEM(BPF_DW, BPF_REG_2, 0, 0),
+	BPF_LD_MAP_FD(BPF_REG_1, 0),
+	/* r6 = bpf_map->inner_map_meta; */
+	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 8),
+	/* r0 = map_lookup_elem(r1, r2); */
+	BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+	/* if (r0 == r6) read *r0; */
+	BPF_JMP_REG(BPF_JEQ, BPF_REG_6, BPF_REG_0, 1),
+	BPF_EXIT_INSN(),
+	BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.fixup_map_hash_8b = { 3 },
+	.prog_type = BPF_PROG_TYPE_XDP,
+	.result = REJECT,
+	.errstr = "R0 invalid mem access 'map_value_or_null'",
+},
-- 
2.38.1