linux-kernel - [PATCH AUTOSEL 5.10 08/18] selftests/bpf: Add verifier test for release

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Date:   Fri, 18 Nov 2022 21:14:49 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Youlin Li <liulin063@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <sashal@...nel.org>, andrii@...nel.org,
        ast@...nel.org, shuah@...nel.org, memxor@...il.com,
        roberto.sassu@...wei.com, mykolal@...com, bpf@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Subject: [PATCH AUTOSEL 5.10 08/18] selftests/bpf: Add verifier test for release_reference()

From: Youlin Li <liulin063@...il.com>

[ Upstream commit 475244f5e06beeda7b557d9dde46a5f439bf3379 ]

Add a test case to ensure that released pointer registers will not be
leaked into the map.

Before fix:

  ./test_verifier 984
    984/u reference tracking: try to leak released ptr reg FAIL
    Unexpected success to load!
    verification time 67 usec
    stack depth 4
    processed 23 insns (limit 1000000) max_states_per_insn 0 total_states 2
    peak_states 2 mark_read 1
    984/p reference tracking: try to leak released ptr reg OK
    Summary: 1 PASSED, 0 SKIPPED, 1 FAILED

After fix:

  ./test_verifier 984
    984/u reference tracking: try to leak released ptr reg OK
    984/p reference tracking: try to leak released ptr reg OK
    Summary: 2 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Youlin Li <liulin063@...il.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Link: https://lore.kernel.org/bpf/20221103093440.3161-2-liulin063@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../selftests/bpf/verifier/ref_tracking.c     | 36 +++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/tools/testing/selftests/bpf/verifier/ref_tracking.c b/tools/testing/selftests/bpf/verifier/ref_tracking.c
index 006b5bd99c08..525d810b10b8 100644
--- a/tools/testing/selftests/bpf/verifier/ref_tracking.c
+++ b/tools/testing/selftests/bpf/verifier/ref_tracking.c
@@ -901,3 +901,39 @@
 	.result_unpriv = REJECT,
 	.errstr_unpriv = "unknown func",
 },
+{
+	"reference tracking: try to leak released ptr reg",
+	.insns = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4),
+		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),
+		BPF_LD_MAP_FD(BPF_REG_1, 0),
+		BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+		BPF_EXIT_INSN(),
+		BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
+
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_LD_MAP_FD(BPF_REG_1, 0),
+		BPF_MOV64_IMM(BPF_REG_2, 8),
+		BPF_MOV64_IMM(BPF_REG_3, 0),
+		BPF_EMIT_CALL(BPF_FUNC_ringbuf_reserve),
+		BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1),
+		BPF_EXIT_INSN(),
+		BPF_MOV64_REG(BPF_REG_8, BPF_REG_0),
+
+		BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),
+		BPF_MOV64_IMM(BPF_REG_2, 0),
+		BPF_EMIT_CALL(BPF_FUNC_ringbuf_discard),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+
+		BPF_STX_MEM(BPF_DW, BPF_REG_9, BPF_REG_8, 0),
+		BPF_EXIT_INSN()
+	},
+	.fixup_map_array_48b = { 4 },
+	.fixup_map_ringbuf = { 11 },
+	.result = ACCEPT,
+	.result_unpriv = REJECT,
+	.errstr_unpriv = "R8 !read_ok"
+},
-- 
2.35.1