From: Matteo Croce <technoboy85@gmail.com>
To: Andrii Nakryiko <andrii@kernel.org>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
Matteo Croce <teknoraver@meta.com>
Subject: [PATCH bpf] bpf: fix argument type in bpf_loop documentation
Date: Wed, 9 Oct 2024 19:05:00 +0100 [thread overview]
Message-ID: <20241009180500.87367-1-technoboy85@gmail.com> (raw)
From: Matteo Croce <teknoraver@meta.com>
The `index` argument to bpf_loop() is threaded as an u64.
This lead in a subtle verifier denial where clang cloned the argument
in another register[1].
[1] https://github.com/systemd/systemd/pull/34650#issuecomment-2401092895
Signed-off-by: Matteo Croce <teknoraver@meta.com>
---
include/uapi/linux/bpf.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 8ab4d8184b9d..874af0186fe8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5371,7 +5371,7 @@ union bpf_attr {
* Currently, the **flags** must be 0. Currently, nr_loops is
* limited to 1 << 23 (~8 million) loops.
*
- * long (\*callback_fn)(u32 index, void \*ctx);
+ * long (\*callback_fn)(u64 index, void \*ctx);
*
* where **index** is the current index in the loop. The index
* is zero-indexed.
--
2.46.0
next reply other threads:[~2024-10-09 18:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-09 18:05 Matteo Croce [this message]
2024-10-09 18:27 ` [PATCH bpf] bpf: fix argument type in bpf_loop documentation Alexei Starovoitov
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