linux-kernel - Re: kernel/trace/trace_events_hist.c:6174 event_hist_trigger_parse() error: we previously assumed 'glob' could be null (see line 6166)

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Message-ID: <20220126102702.6b896353@gandalf.local.home>
Date:   Wed, 26 Jan 2022 10:27:02 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     kbuild@...ts.01.org, Tom Zanussi <zanussi@...nel.org>,
        lkp@...el.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: Re: kernel/trace/trace_events_hist.c:6174
 event_hist_trigger_parse() error: we previously assumed 'glob' could be
 null (see line 6166)

On Wed, 26 Jan 2022 17:50:20 +0300
Dan Carpenter <dan.carpenter@...cle.com> wrote:

> > I just reviewed the code, and it looks like the logic should keep glob from
> > ever being NULL.  
> 
> Smatch can also figure that out, and does not warn, if you have the
> cross function DB.  Unfortunately, that's not feasible for the zero day
> bot because it takes too long to build the DB.
> 
> I was puzzled why this warning showed up now when the code is from 2018.

Well it is called from trigger_process_regex() that gets buf passed in, and
that gets called by trace_boot_init_histograms(),
trace_boot_init_one_event() and event_trigger_regex_write(). All of which
pass in something for that glob parameter.

But I can see it being difficult to catch all that.

I have no problem adding the WARN_ON(), just to make it cleaner.

-- Steve