[PATCH v2] perf sched: Fix memory leaks in __cmd_record

Ian Rogers
2022-08-24T14:57:49Z

An array of strings is passed to cmd_record but not freed. As
cmd_record modifies the array, add another array as a copy that can be
mutated allowing the original array contents to all be freed.

Detected with -fsanitize=address.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/builtin-sched.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 2f6cd1b8b662..a5cf243c337f 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -3355,7 +3355,8 @@ static bool schedstat_events_exposed(void)
static int __cmd_record(int argc, const char **argv)
{
unsigned int rec_argc, i, j;
- const char **rec_argv;
+ char **rec_argv;
+ const char **rec_argv_copy;
const char * const record_args[] = {
"record",
"-a",
@@ -3384,6 +3385,7 @@ static int __cmd_record(int argc, const char **argv)
ARRAY_SIZE(schedstat_args) : 0;

struct tep_event *waking_event;
+ int ret;

/*
* +2 for either "-e", "sched:sched_wakeup" or
@@ -3391,14 +3393,18 @@ static int __cmd_record(int argc, const char **argv)
*/
rec_argc = ARRAY_SIZE(record_args) + 2 + schedstat_argc + argc - 1;
rec_argv = calloc(rec_argc + 1, sizeof(char *));
-
if (rec_argv == NULL)
return -ENOMEM;
+ rec_argv_copy = calloc(rec_argc + 1, sizeof(char *));
+ if (rec_argv_copy == NULL) {
+ free(rec_argv);
+ return -ENOMEM;
+ }

for (i = 0; i < ARRAY_SIZE(record_args); i++)
rec_argv[i] = strdup(record_args[i]);

- rec_argv[i++] = "-e";
+ rec_argv[i++] = strdup("-e");
waking_event = trace_event__tp_format("sched", "sched_waking");
if (!IS_ERR(waking_event))
rec_argv[i++] = strdup("sched:sched_waking");
@@ -3409,11 +3415,19 @@ static int __cmd_record(int argc, const char **argv)
rec_argv[i++] = strdup(schedstat_args[j]);

for (j = 1; j < (unsigned int)argc; j++, i++)
- rec_argv[i] = argv[j];
+ rec_argv[i] = strdup(argv[j]);

BUG_ON(i != rec_argc);

- return cmd_record(i, rec_argv);
+ memcpy(rec_argv_copy, rec_argv, sizeof(char *) * rec_argc);
+ ret = cmd_record(rec_argc, rec_argv_copy);
+
+ for (i = 0; i < rec_argc; i++)
+ free(rec_argv[i]);
+ free(rec_argv);
+ free(rec_argv_copy);
+
+ return ret;
}

int cmd_sched(int argc, const char **argv)
--
2.37.2.609.g9ff673ca1a-goog