From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [PATCH 1/1] tracing/latency_hist Fix memory leak
Date: Fri, 14 Feb 2014 20:59:37 +0100
Message-ID: <52FE75A9.6050305@linutronix.de>
References: <20140214172617.382025623@osadl.org> <20140214172751.776971499@osadl.org>
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Cc: Nicholas Mc Guire <der.herr@hofr.at>,
	Thomas Gleixner <tglx@linutronix.de>,
	RT-users <linux-rt-users@vger.kernel.org>
To: Carsten Emde <C.Emde@osadl.org>
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On 02/14/2014 06:26 PM, Carsten Emde wrote:
> The index_ptr memory that is allocated when printout is started
> currently is only returned when the printout is stopped
> prematurely. It is not returned when the printout regularly
> finishes. Fix this memory leak.
> 
> Signed-off-by: Carsten Emde <C.Emde@osadl.org>
> 
> Index: linux-3.12.10-rt15-somedebug/kernel/trace/latency_hist.c
> ===================================================================
> --- linux-3.12.10-rt15-somedebug.orig/kernel/trace/latency_hist.c
> +++ linux-3.12.10-rt15-somedebug/kernel/trace/latency_hist.c
> @@ -313,6 +313,7 @@ static void *l_next(struct seq_file *m, 
>  
>  	if (++*pos >= MAX_ENTRY_NUM) {
>  		atomic_inc(&my_hist->hist_mode);
> +		kfree(p);
>  		return NULL;
>  	}
>  	*index_ptr = *pos;

Sure on that? If I look at seq_read() I see that there is that ->stop()
is always called after ->start() / ->next() before returning to caller.
Based on this I would say that this patach will introduce a double free
of p.

> 
Sebastian