perf probe: Fix memory leakage when the probe point is not found

[ Upstream commit 12d572e ]

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: ff74178 ("perf probe: Introduce debuginfo to encapsulate dwarf information")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/159438668346.62703.10887420400718492503.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: mhiramat

tools/perf/util/probe-finder.c

@@ -1351,7 +1351,7 @@ int debuginfo__find_trace_events(struct debuginfo *dbg,
 	tf.ntevs = 0;
 
 	ret = debuginfo__find_probes(dbg, &tf.pf);
-	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);