From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tom.zanussi@linux.intel.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
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: Wed, 25 Jul 2018 10:16:53 +0900 [thread overview]
Message-ID: <20180725101653.09e095092a4bb77e6fc558df@kernel.org> (raw)
In-Reply-To: <20180724191331.738eb819@gandalf.local.home>
On Tue, 24 Jul 2018 19:13:31 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> On Tue, 24 Jul 2018 17:30:08 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > I don't see where ->reg() would return anything but 1 on success. Maybe
> > I'm missing something. I'll look some more, but I'm thinking of changing
> > ->reg() to return zero on all success, and negative on all errors and
> > just check those results.
>
> Yeah, I'm going to make these changes. That is, all struct
> event_command .reg functions will return negative on error, and
> zero or positive on everything else. All the checks are going to be
> only for the negative value.
>
> But for the bug fix itself, I believe this should do it. Masami, what
> do you think?
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;
Thank you,
>
> -- Steve
>
> diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
> index d18249683682..8771a27ca60f 100644
> --- a/kernel/trace/trace_events_trigger.c
> +++ b/kernel/trace/trace_events_trigger.c
> @@ -679,6 +679,8 @@ event_trigger_callback(struct event_command *cmd_ops,
> goto out_free;
>
> 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,
> @@ -687,10 +689,11 @@ event_trigger_callback(struct event_command *cmd_ops,
> */
> if (!ret) {
> ret = -ENOENT;
> - goto out_free;
> - } else if (ret < 0)
> - goto out_free;
> - ret = 0;
> + } 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;
>
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2018-07-25 1:16 UTC|newest]
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 [this message]
2018-07-25 2:41 ` Steven Rostedt
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180725101653.09e095092a4bb77e6fc558df@kernel.org \
--to=mhiramat@kernel.org \
--cc=hiraku.toyooka@cybertrust.co.jp \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=rostedt@goodmis.org \
--cc=shuah@kernel.org \
--cc=stable@vger.kernel.org \
--cc=tom.zanussi@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).