linux-kernel - [PATCH bpf-next v2 2/2] bpf: Check link_create parameter for multi

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Message-Id: <20250407035752.1108927-2-chen.dylane@linux.dev>
Date: Mon,  7 Apr 2025 11:57:52 +0800
From: Tao Chen <chen.dylane@...ux.dev>
To: song@...nel.org,
	jolsa@...nel.org,
	ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	rostedt@...dmis.org,
	mhiramat@...nel.org,
	mathieu.desnoyers@...icios.com,
	laoar.shao@...il.com
Cc: bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	Tao Chen <chen.dylane@...ux.dev>
Subject: [PATCH bpf-next v2 2/2] bpf: Check link_create parameter for multi_uprobe

The flags in link_create no used in multi_uprobe, return -EINVAL if
they assigned, keep it same as other link attach apis. And the target_fd
sometimes will be initialized -1 such as probe_uprobe_multi_link in libbpf,
so do not check it at the current stage suggested by jiri.

Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link")
Signed-off-by: Tao Chen <chen.dylane@...ux.dev>
---
 kernel/trace/bpf_trace.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 5cd0af80f..0f4085e8d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3387,6 +3387,13 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
 	/* no support for 32bit archs yet */
 	if (sizeof(u64) != sizeof(void *))
 		return -EOPNOTSUPP;
+	/*
+	 * The target_fd sometimes will be initialized -1 such as
+	 * probe_uprobe_multi_link in libbpf, so do not check it at the
+	 * current stage suggested by jiri.
+	 */
+	if (attr->link_create.flags)
+		return -EINVAL;
 
 	if (!is_uprobe_multi(prog))
 		return -EINVAL;
-- 
2.43.0