From 687f07156b0c99205c21aa4e2986564046d342fe Mon Sep 17 00:00:00 2001
From: Alexei Starovoitov <ast@plumgrid.com>
Date: Tue, 8 Sep 2015 13:40:01 -0700
Subject: bpf: fix out of bounds access in verifier log
when the verifier log is enabled the print_bpf_insn() is doing
bpf_alu_string[BPF_OP(insn->code) >> 4]
and
bpf_jmp_string[BPF_OP(insn->code) >> 4]
where BPF_OP is a 4-bit instruction opcode.
Malformed insns can cause out of bounds access.
Fix it by sizing arrays appropriately.
The bug was found by clang address sanitizer with libfuzzer.
Reported-by: Yonghong Song <yhs@plumgrid.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
kernel/bpf/verifier.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
(limited to 'kernel')
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index ed12e385fb75..b074b23000d6 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -283,7 +283,7 @@ static const char *const bpf_class_string[] = {
[BPF_ALU64] = "alu64",
};
-static const char *const bpf_alu_string[] = {
+static const char *const bpf_alu_string[16] = {
[BPF_ADD >> 4] = "+=",
[BPF_SUB >> 4] = "-=",
[BPF_MUL >> 4] = "*=",
@@ -307,7 +307,7 @@ static const char *const bpf_ldst_string[] = {
[BPF_DW >> 3] = "u64",
};
-static const char *const bpf_jmp_string[] = {
+static const char *const bpf_jmp_string[16] = {
[BPF_JA >> 4] = "jmp",
[BPF_JEQ >> 4] = "==",
[BPF_JGT >> 4] = ">",
--
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