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Date:   Wed, 11 Aug 2021 10:35:22 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     LKML <linux-kernel@vger.kernel.org>
Cc:     Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Tom Zanussi <zanussi@kernel.org>,
        Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH] tracing / histogram: Fix NULL pointer dereference on
 strcmp() on NULL event name
Message-ID: <20210811103522.0cac5f1a@oasis.local.home>
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On Sun, 8 Aug 2021 00:30:11 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index 949ef09dc537..a48aa2a2875b 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -3430,6 +3430,8 @@ trace_action_create_field_var(struct hist_trigger_data *hist_data,
>  			event = data->match_data.event;
>  		}
>  
> +		if (!event)
> +			goto free;
>  		/*
>  		 * At this point, we're looking at a field on another
>  		 * event.  Because we can't modify a hist trigger on
> -- 

Tom,

Is this OK? I'm going to start running this through my tests and when
it's done, I'm going to send it off to Linus.

-- Steve