linux-kernel - [PATCH bpf-next] bpf: Disable migrate when kprobe_multi attach to access bpf_prog

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250804121615.1843956-1-chen.dylane@linux.dev>
Date: Mon,  4 Aug 2025 20:16:15 +0800
From: Tao Chen <chen.dylane@...ux.dev>
To: ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	martin.lau@...ux.dev,
	eddyz87@...il.com,
	song@...nel.org,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	jolsa@...nel.org,
	mattbobrowski@...gle.com,
	rostedt@...dmis.org,
	mhiramat@...nel.org,
	mathieu.desnoyers@...icios.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] bpf: Disable migrate when kprobe_multi attach to access bpf_prog_active

The syscall link_create not protected by bpf_disable_instrumentation,
accessing percpu data bpf_prog_active should use cpu local_lock when
kprobe_multi program attach.

Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
Signed-off-by: Tao Chen <chen.dylane@...ux.dev>
---
 kernel/trace/bpf_trace.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3ae52978cae..f6762552e8e 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2728,23 +2728,23 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
 	struct pt_regs *regs;
 	int err;
 
+	migrate_disable();
 	if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
 		bpf_prog_inc_misses_counter(link->link.prog);
 		err = 1;
 		goto out;
 	}
 
-	migrate_disable();
 	rcu_read_lock();
 	regs = ftrace_partial_regs(fregs, bpf_kprobe_multi_pt_regs_ptr());
 	old_run_ctx = bpf_set_run_ctx(&run_ctx.session_ctx.run_ctx);
 	err = bpf_prog_run(link->link.prog, regs);
 	bpf_reset_run_ctx(old_run_ctx);
 	rcu_read_unlock();
-	migrate_enable();
 
  out:
 	__this_cpu_dec(bpf_prog_active);
+	migrate_enable();
 	return err;
 }
 
-- 
2.48.1