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| author | Paul Eggert <eggert@cs.ucla.edu> | 2026-05-17 22:49:44 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2026-05-18 23:10:42 -0700 |
| commit | 07fe0b297bc7b9c4e344eedd8244a73edda95c77 (patch) | |
| tree | a444012254289167cc0ea12e3ca5654876dd8fa2 /src/fns.c | |
| parent | 7587bb2654a6c22f8c9709cefd3ad8d45938b199 (diff) | |
Fix undefined behavior in maybe_resize_hash_table
Problem discovered with GCC 16.1.1 -fsanitize=undefined.
* src/fns.c (maybe_resize_hash_table): Avoid undefined
behavior when h->key_and_value or h->hash are null pointers,
in which case we call memcpy (destination, NULL, 0)
which has undefined behavior in C89 through C23.
Diffstat (limited to 'src/fns.c')
| -rw-r--r-- | src/fns.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/src/fns.c b/src/fns.c index 1158f100ea0..a2312ffa1b9 100644 --- a/src/fns.c +++ b/src/fns.c @@ -4975,13 +4975,15 @@ maybe_resize_hash_table (struct Lisp_Hash_Table *h) Lisp_Object *key_and_value = hash_table_alloc_bytes (2 * new_size * sizeof *key_and_value); - memcpy (key_and_value, h->key_and_value, - 2 * old_size * sizeof *key_and_value); + if (old_size) + memcpy (key_and_value, h->key_and_value, + 2 * old_size * sizeof *key_and_value); for (ptrdiff_t i = 2 * old_size; i < 2 * new_size; i++) key_and_value[i] = HASH_UNUSED_ENTRY_KEY; hash_hash_t *hash = hash_table_alloc_bytes (new_size * sizeof *hash); - memcpy (hash, h->hash, old_size * sizeof *hash); + if (old_size) + memcpy (hash, h->hash, old_size * sizeof *hash); ptrdiff_t old_index_size = hash_table_index_size (h); ptrdiff_t index_bits = compute_hash_index_bits (new_size); |