[PATCH] mm: transhuge-stress: fix potential memory leak on realloc failure

[Haofeng Li <920484857@qq.com>]

From: Haofeng Li <lihaofeng@kylinos.cn>

When realloc() fails in transhuge-stress test, the original code
exits immediately without freeing the previously allocated memory,
causing a memory leak. This patch introduces a temporary pointer
to hold the realloc result, ensuring proper cleanup by freeing
the original map before exiting on allocation failure.

Signed-off-by: Haofeng Li <lihaofeng@kylinos.cn>
---
 tools/testing/selftests/mm/transhuge-stress.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/transhuge-stress.c b/tools/testing/selftests/mm/transhuge-stress.c
index 68201192e37c..cbe86c5b8de0 100644
--- a/tools/testing/selftests/mm/transhuge-stress.c
+++ b/tools/testing/selftests/mm/transhuge-stress.c
@@ -30,7 +30,7 @@ int main(int argc, char **argv)
 	int i = 0;
 	char *name = NULL;
 	double s;
-	uint8_t *map;
+	uint8_t *map, *map_tmp;
 	size_t map_len;
 	int pagemap_fd;
 	int duration = 0;
@@ -107,9 +107,12 @@ int main(int argc, char **argv)
 
 				nr_succeed++;
 				if (idx >= map_len) {
-					map = realloc(map, idx + 1);
-					if (!map)
+					map_tmp = realloc(map, idx + 1);
+					if (!map_tmp) {
+						free(map);
 						ksft_exit_fail_msg("map realloc\n");
+					}
+					map = map_tmp;
 					memset(map + map_len, 0, idx + 1 - map_len);
 					map_len = idx + 1;
 				}
-- 
2.25.1