selftests/resctrl: Don't leak buffer in fill_cache()

The error path in fill_cache() does return before the allocated buffer
is freed leaking the buffer.

The leak was introduced when fill_cache_read() started to return errors
in commit c7b607fa ("selftests/resctrl: Fix null pointer
dereference on open failed"), before that both fill functions always
returned 0.

Move free() earlier to prevent the mem leak.

Fixes: c7b607fa ("selftests/resctrl: Fix null pointer dereference on open failed")
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan (Fujitsu) <tan.shaopeng@fujitsu.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/resctrl/fill_buf.c

@@ -177,12 +177,13 @@ fill_cache(unsigned long long buf_size, int malloc_and_init, int memflush,
 	else
 		ret = fill_cache_write(start_ptr, end_ptr, resctrl_val);
 
+	free(startptr);
+
 	if (ret) {
 		printf("\n Error in fill cache read/write...\n");
 		return -1;
 	}
 
-	free(startptr);
 
 	return 0;
 }