From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH bpf-next 8/8] bpf: ensure that r0 is marked scratched after any function call
Date: Wed, 1 Mar 2023 21:32:16 -0800 [thread overview]
Message-ID: <20230302053216.1426015-9-andrii@kernel.org> (raw)
In-Reply-To: <20230302053216.1426015-1-andrii@kernel.org>
r0 is important (unless called function is void-returning, but that's
taken care of by print_verifier_state() anyways) in verifier logs.
Currently for helpers we seem to print it in verifier log, but for
kfuncs we don't.
Instead of figuring out where in the maze of code we accidentally set r0
as scratched for helpers and why we don't do that for kfuncs, just
enforce that after any function call r0 is marked as scratched.
Also, perhaps, we should reconsider "scratched" terminology, as it's
mightily confusing. "Touched" would seem more appropriate. But I left
that for follow ups for now.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
kernel/bpf/verifier.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 666e416dc8a2..0004c9f3737f 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -15001,6 +15001,8 @@ static int do_check(struct bpf_verifier_env *env)
err = check_helper_call(env, insn, &env->insn_idx);
if (err)
return err;
+
+ mark_reg_scratched(env, BPF_REG_0);
} else if (opcode == BPF_JA) {
if (BPF_SRC(insn->code) != BPF_K ||
insn->imm != 0 ||
--
2.30.2
prev parent reply other threads:[~2023-03-02 5:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-02 5:32 [PATCH bpf-next 0/8] Misc fixes and preliminaries for iterators Andrii Nakryiko
2023-03-02 5:32 ` [PATCH bpf-next 1/8] bpf: improve stack slot state printing Andrii Nakryiko
2023-03-02 5:32 ` [PATCH bpf-next 2/8] bpf: improve regsafe() checks for PTR_TO_{MEM,BUF,TP_BUFFER} Andrii Nakryiko
2023-03-02 5:32 ` [PATCH bpf-next 3/8] selftests/bpf: enhance align selftest's expected log matching Andrii Nakryiko
2023-03-02 5:32 ` [PATCH bpf-next 4/8] bpf: honor env->test_state_freq flag in is_state_visited() Andrii Nakryiko
2023-03-02 5:32 ` [PATCH bpf-next 5/8] selftests/bpf: adjust log_fixup's buffer size for proper truncation Andrii Nakryiko
2023-03-02 5:32 ` [PATCH bpf-next 6/8] bpf: clean up visit_insn()'s instruction processing Andrii Nakryiko
2023-03-02 5:32 ` [PATCH bpf-next 7/8] bpf: fix visit_insn()'s detection of BPF_FUNC_timer_set_callback helper Andrii Nakryiko
2023-03-02 5:32 ` Andrii Nakryiko [this message]
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