linux-kernel - Re: [PATCH v2] ftrace: Fix use-after-free for dynamic ftrace

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

Message-ID: <20221102232334.0c1ae93b@rorschach.local.home>
Date:   Wed, 2 Nov 2022 23:23:34 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Li Huafei <lihuafei1@...wei.com>
Cc:     <mhiramat@...nel.org>, <mark.rutland@....com>,
        <linux-kernel@...r.kernel.org>,
        <linux-trace-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] ftrace: Fix use-after-free for dynamic ftrace_ops

On Thu, 3 Nov 2022 11:10:10 +0800
Li Huafei <lihuafei1@...wei.com> wrote:

> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -3028,18 +3028,8 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command)
>  		command |= FTRACE_UPDATE_TRACE_FUNC;
>  	}
>  
> -	if (!command || !ftrace_enabled) {
> -		/*
> -		 * If these are dynamic or per_cpu ops, they still
> -		 * need their data freed. Since, function tracing is
> -		 * not currently active, we can just free them
> -		 * without synchronizing all CPUs.
> -		 */
> -		if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
> -			goto free_ops;
> -
> -		return 0;
> -	}
> +	if (!command || !ftrace_enabled)
> +		goto out;
>  

Hi Li,

I think you misunderstood me. What I was suggesting was to get rid of
the ftrace_enabled check. The DYNAMIC part is most definitely needed.

	if (!command) {
		if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
			goto out;
		return 0;
	}

-- Steve