linux-kernel - Re: [PATCH 2/2] tracing: Fix kmemleak in set_trigger

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Date:   Wed, 23 Aug 2017 10:41:55 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Chunyu Hu <chuhu@...hat.com>
Cc:     mingo@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] tracing: Fix kmemleak in set_trigger_filter

On Wed, 23 Aug 2017 10:38:36 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> > +++ b/kernel/trace/trace_events_trigger.c
> > @@ -739,7 +739,7 @@ int set_trigger_filter(char *filter_str,
> >  	/* The filter is for the 'trigger' event, not the triggered event */
> >  	ret = create_event_filter(file->event_call, filter_str, false, &filter);  
> 
> The filter is allocated by create_event_filter. If that returns a
> failure, then that should be the one to free it. It is bad taste to
> require the calling function to require it.

I take that back. I just read the comment above create_event_filter():

 * On success, returns 0 and *@...terp points to the new filter.  On
 * failure, returns -errno and *@...terp may point to %NULL or to a new
 * filter.  In the latter case, the returned filter contains error
 * information if @set_str is %true and the caller is responsible for
 * freeing it.

So filter contains an error string when it fails. It seems that we
should somehow propagate that up the chain to display. I'll look more
into this.

-- Steve