perf record: Fix possible incorrect free in record__switch_output()

perf_data__switch() may not assign a legal value to 'new_filename'.
In this case, 'new_filename' uses the on-stack value, which may cause a
incorrect free and unexpected result.

Fixes: 03724b2e ("perf record: Allow to limit number of reported perf.data files")
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20240119040304.3708522-2-yangjihong1@huawei.comSigned-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/builtin-record.c

@@ -1830,8 +1830,8 @@ static int
 record__switch_output(struct record *rec, bool at_exit)
 {
 	struct perf_data *data = &rec->data;
+	char *new_filename = NULL;
 	int fd, err;
-	char *new_filename;
 
 	/* Same Size:      "2015122520103046"*/
 	char timestamp[] = "InvalidTimestamp";