On Sat, 20 Dec 2025 19:16:43 +0800 Li Wang liwang@redhat.com 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
Can we fix that typo while we're in there? "reservation".
... # Writing to this path: /mnt/huge/test # Writing this size: -1610612736 <--------
Switch size to size_t and parse -s using strtoull() with proper validation. Also print the size using %zu.
This makes the test utility more robust and avoids undefined/incorrect behavior with large or invalid -s values.
...
--- 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 +86,20 @@ int main(int argc, char **argv) while ((c = getopt(argc, argv, "s:p:m:owlrn")) != -1) { switch (c) { case 's':
size = atoi(optarg);
errno = 0;char *end = NULL;unsigned long long tmp = strtoull(optarg, &end, 10);
Coding-style nits: we do accept c99-style definitions nowadays but I do think our eyes prefer the less surprising "definitions come before code" style. So the above could be
char *end = NULL; unsigned long long tmp = strtoull(optarg, &end, 10);
errno = 0;
Also, `errno' belongs to libc. It seems wrong to be altering it from within our client code.
if (errno || end == optarg || *end != '\0') {errno = EINVAL;perror("Invalid -s size");exit_usage();}if (tmp == 0) {errno = EINVAL;perror("size not found");exit_usage();}size = (size_t)tmp; break;
I'm not really clear on what problems we're trying to solve here, but this all seems like a lot of fuss. Can we just do
if (sscanf(optarg, "%zu", &size) != 1)
?
case 'p': strncpy(path, optarg, sizeof(path) - 1);@@ -131,7 +144,7 @@ int main(int argc, char **argv) } if (size != 0) {
printf("Writing this size: %d\n", size);
printf("Writing this size: %zu\n", size);