linux-kernel - [PATCH v2 3/4] perf-probe: Fix memory leakage when the probe point is not found

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Date:   Fri, 10 Jul 2020 22:11:23 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Cc:     Oleg Nesterov <oleg@...hat.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, mhiramat@...nel.org,
        Andi Kleen <andi@...stfloor.org>,
        Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH v2 3/4] perf-probe: Fix memory leakage when the probe point is not found

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>
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);