linux-kernel - Re: [PATCH 3/4] perf-probe: Fix memory leakage when the probe point is not found

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Message-ID: <20200710111626.GM874@linux.vnet.ibm.com>
Date:   Fri, 10 Jul 2020 16:46:26 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Oleg Nesterov <oleg@...hat.com>, linux-kernel@...r.kernel.org,
        Andi Kleen <andi@...stfloor.org>,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 3/4] perf-probe: Fix memory leakage when the probe point
 is not found

* Masami Hiramatsu <mhiramat@...nel.org> [2020-07-09 17:07:22]:

> Fix the memory leakage in debuginfo__find_trace_events() when the probe
> point is not found in the debuginfo. If there is no probe point found in
> the debuginfo, debuginfo__find_probes() will NOT return -ENOENT, but 0.
> Thus the caller of debuginfo__find_probes() must check the tf.ntevs and
> release the allocated memory for the array of struct probe_trace_event.
> 
> The current code releases the memory only if the debuginfo__find_probes()
> hits an error but not checks tf.ntevs. In the result, the memory allocated
> on *tevs are not released if tf.ntevs == 0.
> 
> This fixes the memory leakage by checking tf.ntevs == 0 in addition to
> ret < 0.
> 
> Fixes: ff741783506c ("perf probe: Introduce debuginfo to encapsulate dwarf information")
> Cc: stable@...r.kernel.org
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>


Looks good to me.

Reviewed-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

> ---
>  tools/perf/util/probe-finder.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 9963e4e8ea20..659024342e9a 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -1467,7 +1467,7 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
>  	if (ret >= 0 && tf.pf.skip_empty_arg)
>  		ret = fill_empty_trace_arg(pev, tf.tevs, tf.ntevs);
> 
> -	if (ret < 0) {
> +	if (ret < 0 || tf.ntevs == 0) {
>  		for (i = 0; i < tf.ntevs; i++)
>  			clear_probe_trace_event(&tf.tevs[i]);
>  		zfree(tevs);
> 

-- 
Thanks and Regards
Srikar Dronamraju