From nobody Mon Oct 6 17:04:11 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3EC0F221550; Sat, 19 Jul 2025 17:57:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752947874; cv=none; b=r6veibJNUxowvlK9ksMuLTLupVmkzDz16LTG4qp310JdSdIEak+ysi7ajmD/bzXnyTDL5He5IbtVImvw9w0b6wWnHoY8Chy/i2S5TNgSDwAaAtTfAFeWvqEawdg7z8vle4CEMQAfTYabmHDVqZzdBiLq2jEWGYYyKCB71IYh4oU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752947874; c=relaxed/simple; bh=SgO5r3HKnNBU0sLniQLn4+H/1Vma8XHldf0X3/vnXwc=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=mxDTThmPiEfJ6hHg0zB8rrgnUtO0QTCJKiPQkQMiiPWwV8ncNaOFQooKmQEhnYthYN539c/YlWyKJSB2EyTHBRhi9kxRL0IIbOxAruHDLq1r9jrbss1yhRt7vVUOV7Tdcyjo8Yf4EBXmQxG9avP6ccgBsJ4DlV17GgeV36/egdw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U7A9GgoL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="U7A9GgoL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C8795C4CEF5; Sat, 19 Jul 2025 17:57:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752947873; bh=SgO5r3HKnNBU0sLniQLn4+H/1Vma8XHldf0X3/vnXwc=; h=Date:From:To:Cc:Subject:References:From; b=U7A9GgoLDs99xBBf3ewA2NCTsfRjYQxUwpS3gO5dd5ps0CBIdfD3YsbwKagrmtm7G YC3JXQtrGxpkStp7XaleCXWMjbj6vKV5hlf235AwWvQwUtLbSp9dHxq79hzOgJODTA 8JBYU3jVg4jE7GXN1c8iUSkOrHQsG/VwOkDLEw0JRoBWadmJT6+RWP5jHxR6YvH6lk 7ndL+IBC1quvU8LtgVhpzjlpkQz7iCQuB7mONoVAaLPiF+tF0Tj9k5tyZ1NSXiJP2M 36JpuT+CMWKDpDyVJ7zTP0PP1olrK/RgYgcWB23EIRFxsQltd4T7lOGCbI8Xm2dKgE WdAMTtMubzHXg== Received: from rostedt by gandalf with local (Exim 4.98.2) (envelope-from ) id 1udBpE-000000085Ht-00DT; Sat, 19 Jul 2025 13:58:20 -0400 Message-ID: <20250719175819.850873535@kernel.org> User-Agent: quilt/0.68 Date: Sat, 19 Jul 2025 13:57:56 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, =?UTF-8?q?Fusheng=20Huang(=E9=BB=84=E5=AF=8C=E7=94=9F)?= Subject: [for-linus][PATCH 2/2] tracing: Add down_write(trace_event_sem) when adding trace event References: <20250719175754.996594784@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Steven Rostedt When a module is loaded, it adds trace events defined by the module. It may also need to modify the modules trace printk formats to replace enum names with their values. If two modules are loaded at the same time, the adding of the event to the ftrace_events list can corrupt the walking of the list in the code that is modifying the printk format strings and crash the kernel. The addition of the event should take the trace_event_sem for write while it adds the new event. Also add a lockdep_assert_held() on that semaphore in __trace_add_event_dirs() as it iterates the list. Cc: stable@vger.kernel.org Cc: Mathieu Desnoyers Acked-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/20250718223158.799bfc0c@batman.local.home Reported-by: Fusheng Huang(=E9=BB=84=E5=AF=8C=E7=94=9F) Closes: https://lore.kernel.org/all/20250717105007.46ccd18f@batman.local.ho= me/ Fixes: 110bf2b764eb6 ("tracing: add protection around module events unload") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 120531268abf..d01e5c910ce1 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -3136,7 +3136,10 @@ __register_event(struct trace_event_call *call, stru= ct module *mod) if (ret < 0) return ret; =20 + down_write(&trace_event_sem); list_add(&call->list, &ftrace_events); + up_write(&trace_event_sem); + if (call->flags & TRACE_EVENT_FL_DYNAMIC) atomic_set(&call->refcnt, 0); else @@ -3750,6 +3753,8 @@ __trace_add_event_dirs(struct trace_array *tr) struct trace_event_call *call; int ret; =20 + lockdep_assert_held(&trace_event_sem); + list_for_each_entry(call, &ftrace_events, list) { ret =3D __trace_add_new_event(call, tr); if (ret < 0) --=20 2.47.2