linux-kernel - [PATCH 5.1 054/138] bpf: fix div64 overflow tests to properly detect errors

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Message-Id: <20190712121630.742274478@linuxfoundation.org>
Date:   Fri, 12 Jul 2019 14:18:38 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.1 054/138] bpf: fix div64 overflow tests to properly detect errors

[ Upstream commit 3e0682695199bad51dd898fe064d1564637ff77a ]

If the result of the division is LLONG_MIN, current tests do not detect
the error since the return value is truncated to a 32-bit value and ends
up being 0.

Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 .../testing/selftests/bpf/verifier/div_overflow.c  | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/bpf/verifier/div_overflow.c b/tools/testing/selftests/bpf/verifier/div_overflow.c
index bd3f38dbe796..acab4f00819f 100644
--- a/tools/testing/selftests/bpf/verifier/div_overflow.c
+++ b/tools/testing/selftests/bpf/verifier/div_overflow.c
@@ -29,8 +29,11 @@
 	"DIV64 overflow, check 1",
 	.insns = {
 	BPF_MOV64_IMM(BPF_REG_1, -1),
-	BPF_LD_IMM64(BPF_REG_0, LLONG_MIN),
-	BPF_ALU64_REG(BPF_DIV, BPF_REG_0, BPF_REG_1),
+	BPF_LD_IMM64(BPF_REG_2, LLONG_MIN),
+	BPF_ALU64_REG(BPF_DIV, BPF_REG_2, BPF_REG_1),
+	BPF_MOV32_IMM(BPF_REG_0, 0),
+	BPF_JMP_REG(BPF_JEQ, BPF_REG_0, BPF_REG_2, 1),
+	BPF_MOV32_IMM(BPF_REG_0, 1),
 	BPF_EXIT_INSN(),
 	},
 	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
@@ -40,8 +43,11 @@
 {
 	"DIV64 overflow, check 2",
 	.insns = {
-	BPF_LD_IMM64(BPF_REG_0, LLONG_MIN),
-	BPF_ALU64_IMM(BPF_DIV, BPF_REG_0, -1),
+	BPF_LD_IMM64(BPF_REG_1, LLONG_MIN),
+	BPF_ALU64_IMM(BPF_DIV, BPF_REG_1, -1),
+	BPF_MOV32_IMM(BPF_REG_0, 0),
+	BPF_JMP_REG(BPF_JEQ, BPF_REG_0, BPF_REG_1, 1),
+	BPF_MOV32_IMM(BPF_REG_0, 1),
 	BPF_EXIT_INSN(),
 	},
 	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
-- 
2.20.1