Re: [PATCH v3 1/3] selftests/mm/write_to_hugetlbfs: parse -s as size_t

On 12/21/25 7:26 AM, Li Wang wrote:

write_to_hugetlbfs currently parses the -s size argument with atoi() into an int. This silently accepts malformed input, cannot report overflow, and can truncate large sizes.

--- Error log --- # uname -r 6.12.0-xxx.el10.aarch64+64k

# ls /sys/kernel/mm/hugepages/hugepages-* hugepages-16777216kB/ hugepages-2048kB/ hugepages-524288kB/

#./charge_reserved_hugetlb.sh -cgroup-v2 # ----------------------------------------- ... # nr hugepages = 10 # writing cgroup limit: 5368709120 # writing reseravation limit: 5368709120 ... # Writing to this path: /mnt/huge/test # Writing this size: -1610612736 <--------

Switch the size variable to size_t and parse -s with sscanf("%zu", ...). Also print the size using %zu.

This avoids incorrect behavior with large -s values and makes the utility more robust.

Signed-off-by: Li Wang liwang@redhat.com Cc: David Hildenbrand david@kernel.org Cc: Mark Brown broonie@kernel.org Cc: Shuah Khan shuah@kernel.org Cc: Waiman Long longman@redhat.com Acked-by: David Hildenbrand (Red Hat) david@kernel.org

---

tools/testing/selftests/mm/write_to_hugetlbfs.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/write_to_hugetlbfs.c b/tools/testing/selftests/mm/write_to_hugetlbfs.c index 34c91f7e6128..ecb5f7619960 100644 --- a/tools/testing/selftests/mm/write_to_hugetlbfs.c +++ b/tools/testing/selftests/mm/write_to_hugetlbfs.c @@ -68,7 +68,7 @@ int main(int argc, char **argv) int key = 0; int *ptr = NULL; int c = 0;

• int size = 0;

• size_t size = 0; char path[256] = ""; enum method method = MAX_METHOD; int want_sleep = 0, private = 0;

@@ -86,7 +86,10 @@ int main(int argc, char **argv) while ((c = getopt(argc, argv, "s:p:m:owlrn")) != -1) { switch (c) { case 's':

• 	size = atoi(optarg);
  

• 	if (sscanf(optarg, "%zu", &size) != 1) {
  

• 		perror("Invalid -s.");
  

• 		exit_usage();
  

• 	}
  break;
  

  case 'p': strncpy(path, optarg, sizeof(path) - 1);

@@ -131,7 +134,7 @@ int main(int argc, char **argv) } if (size != 0) {

• printf("Writing this size: %d\n", size);
  

• printf("Writing this size: %zu\n", size);
  

  } else { errno = EINVAL; perror("size not found");

LGTM

Acked-by: Waiman Long longman@redhat.com