[PATCH 4.4 18/78] perf probe: Avoid calling freeing routine multiple times for same pointer

Greg Kroah-Hartman
2019-08-22T17:22:21Z

[ Upstream commit d95daf5accf4a72005daa13fbb1d1bd8709f2861 ]

When perf_add_probe_events() we call cleanup_perf_probe_events() for the
pev pointer it receives, then, as part of handling this failure the main
'perf probe' goes on and calls cleanup_params() and that will again call
cleanup_perf_probe_events()for the same pointer, so just set nevents to
zero when handling the failure of perf_add_probe_events() to avoid the
double free.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-x8qgma4g813z96dvtw9w219q@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/builtin-probe.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 9d4ac90ca87e4..66fb1d53d0f08 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -613,6 +613,16 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)

ret = perf_add_probe_events(params.events, params.nevents);
if (ret < 0) {
+
+ /*
+ * When perf_add_probe_events() fails it calls
+ * cleanup_perf_probe_events(pevs, npevs), i.e.
+ * cleanup_perf_probe_events(params.events, params.nevents), which
+ * will call clear_perf_probe_event(), so set nevents to zero
+ * to avoid cleanup_params() to call clear_perf_probe_event() again
+ * on the same pevs.
+ */
+ params.nevents = 0;
pr_err_with_code(" Error: Failed to add events.", ret);
return ret;
}
--
2.20.1