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From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>,
	Ingo Molnar <mingo@redhat.com>, Shuah Khan <shuah@kernel.org>,
	Hiraku Toyooka <hiraku.toyooka@cybertrust.co.jp>,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH 1/3] [BUGFIX] tracing: Fix double free of event_trigger_data
Date: Tue, 24 Jul 2018 22:41:49 -0400
Message-ID: <20180724224149.0767fd13@gandalf.local.home> (raw)
In-Reply-To: <20180725101653.09e095092a4bb77e6fc558df@kernel.org>

On Wed, 25 Jul 2018 10:16:53 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> Hm, as far as I can see, when register_trigger() returns >= 0, it already
> calls ->init the trigger_data. This means its refcount++, and in that
> case, below patch will miss to free the trigger_data.
> How about below for tentative fix?
> 
> 	if (!ret) {
> 		ret = -ENOENT;
> 		/* We have to forcibly free the trigger_data */
> 		goto out_free;
> 	} else if (ret > 0)
> 		ret = 0;

Or better yet, match it properly:

out_reg:
	/* Up the trigger_data count to make sure reg doesn't free it on failure */
	event_trigger_init(trigger_ops, trigger_data);
	ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
	/*
	 * The above returns on success the # of functions enabled,
	 * but if it didn't find any functions it returns zero.
	 * Consider no functions a failure too.
	 */
	if (!ret) {
		cmd_ops->unreg(glob, trigger_ops, trigger_data, file);
		ret = -ENOENT;
	} else if (ret > 0)
		ret = 0;

	/* Down the counter of trigger_data or free it if not used anymore */
	event_trigger_free(trigger_ops, trigger_data);
 out:
	return ret;

-- Steve

  reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-13 16:27 [PATCH 0/3] tracing: Fix bugs on snapshot feature Masami Hiramatsu
2018-07-13 16:27 ` [PATCH 1/3] [BUGFIX] tracing: Fix double free of event_trigger_data Masami Hiramatsu
2018-07-24  2:10   ` Steven Rostedt
2018-07-24 15:09     ` Masami Hiramatsu
2018-07-24 20:49       ` Steven Rostedt
2018-07-24 21:30         ` Steven Rostedt
2018-07-24 23:13           ` Steven Rostedt
2018-07-25  1:16             ` Masami Hiramatsu
2018-07-25  2:41               ` Steven Rostedt [this message]
2018-07-25 14:14                 ` Masami Hiramatsu
2018-07-25 16:01           ` Tom Zanussi
2018-07-25 16:09             ` Steven Rostedt
2018-07-25  1:05         ` Masami Hiramatsu
2018-07-13 16:28 ` [PATCH 2/3] [BUGFIX] ring_buffer: tracing: Inherit the tracing setting to next ring buffer Masami Hiramatsu
2018-07-24  2:25   ` Steven Rostedt
2018-07-24 14:30     ` Masami Hiramatsu
2018-07-13 16:28 ` [PATCH 3/3] selftests/ftrace: Add snapshot and tracing_on test case Masami Hiramatsu

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