linux-kernel - [RFC PATCH net-next 1/5] selftests/bpf: add test for mixed signed and unsigned bounds checks

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Message-ID: <37417674-8be8-bdcb-07e3-303083076452@solarflare.com>
Date:   Wed, 7 Jun 2017 15:58:14 +0100
From:   Edward Cree <ecree@...arflare.com>
To:     <davem@...emloft.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>
CC:     <netdev@...r.kernel.org>,
        iovisor-dev <iovisor-dev@...ts.iovisor.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH net-next 1/5] selftests/bpf: add test for mixed signed and
 unsigned bounds checks

Currently fails due to bug in verifier bounds handling.

Signed-off-by: Edward Cree <ecree@...arflare.com>
---
 tools/testing/selftests/bpf/test_verifier.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index cabb19b..5074cfa 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -5169,6 +5169,32 @@ static struct bpf_test tests[] = {
 		},
 		.result = ACCEPT,
 	},
+	{
+		"bounds checks mixing signed and unsigned",
+		.insns = {
+			BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+			BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+			BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+			BPF_LD_MAP_FD(BPF_REG_1, 0),
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_map_lookup_elem),
+			BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 7),
+			BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, -8),
+			BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_10, -16),
+			BPF_MOV64_IMM(BPF_REG_2, -1),
+			BPF_JMP_REG(BPF_JGT, BPF_REG_1, BPF_REG_2, 3),
+			BPF_JMP_IMM(BPF_JSGT, BPF_REG_1, 1, 2),
+			BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1),
+			BPF_ST_MEM(BPF_B, BPF_REG_0, 0, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.fixup_map1 = { 3 },
+		.errstr_unpriv = "R0 pointer arithmetic prohibited",
+		.errstr = "R0 min value is negative, either use unsigned index or do a if (index >=0) check.",
+		.result = REJECT,
+		.result_unpriv = REJECT,
+	},
 };
 
 static int probe_filter_length(const struct bpf_insn *fp)