From: Andrii Nakryiko <andriin@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>, <ast@fb.com>,
<daniel@iogearbox.net>
Cc: <andrii.nakryiko@gmail.com>, <kernel-team@fb.com>,
Andrii Nakryiko <andriin@fb.com>, Yonghong Song <yhs@fb.com>
Subject: [PATCH bpf-next 1/4] libbpf: fix detection of BPF helper call instruction
Date: Wed, 19 Aug 2020 23:14:08 -0700 [thread overview]
Message-ID: <20200820061411.1755905-1-andriin@fb.com> (raw)
BPF_CALL | BPF_JMP32 is explicitly not allowed by verifier for BPF helper
calls, so don't detect it as a valid call. Also drop the check on func_id
pointer, as it's currently always non-null.
Reported-by: Yonghong Song <yhs@fb.com>
Fixes: 109cea5a594f ("libbpf: Sanitize BPF program code for bpf_probe_read_{kernel, user}[_str]")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
tools/lib/bpf/libbpf.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 77d420c02094..92ca4eb6ba2d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5844,14 +5844,12 @@ static int bpf_object__collect_reloc(struct bpf_object *obj)
static bool insn_is_helper_call(struct bpf_insn *insn, enum bpf_func_id *func_id)
{
- __u8 class = BPF_CLASS(insn->code);
-
- if ((class == BPF_JMP || class == BPF_JMP32) &&
+ if (BPF_CLASS(insn->code) == BPF_JMP &&
BPF_OP(insn->code) == BPF_CALL &&
BPF_SRC(insn->code) == BPF_K &&
- insn->src_reg == 0 && insn->dst_reg == 0) {
- if (func_id)
- *func_id = insn->imm;
+ insn->src_reg == 0 &&
+ insn->dst_reg == 0) {
+ *func_id = insn->imm;
return true;
}
return false;
--
2.24.1
next reply other threads:[~2020-08-20 6:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-20 6:14 Andrii Nakryiko [this message]
2020-08-20 6:14 ` [PATCH bpf-next 2/4] libbpf: fix libbpf build on compilers missing __builtin_mul_overflow Andrii Nakryiko
2020-08-20 14:21 ` Yonghong Song
2020-08-20 6:14 ` [PATCH bpf-next 3/4] selftests/bpf: fix two minor compilation warnings reported by GCC 4.9 Andrii Nakryiko
2020-08-20 14:21 ` Yonghong Song
2020-08-20 6:14 ` [PATCH bpf-next 4/4] selftests/bpf: list newest Clang built-ins needed for some CO-RE selftests Andrii Nakryiko
2020-08-20 14:22 ` Yonghong Song
2020-08-20 14:17 ` [PATCH bpf-next 1/4] libbpf: fix detection of BPF helper call instruction Yonghong Song
2020-08-20 15:16 ` Daniel Borkmann
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