diff options
| -rw-r--r-- | src/atomic_ops_malloc.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/src/atomic_ops_malloc.c b/src/atomic_ops_malloc.c index 124c87c..3753016 100644 --- a/src/atomic_ops_malloc.c +++ b/src/atomic_ops_malloc.c @@ -135,6 +135,10 @@ static char *get_mmaped(size_t sz) return result; } +/* Saturated addition of size_t values. Used to avoid value wrap */ +/* around on overflow. The arguments should have no side effects. */ +#define SIZET_SAT_ADD(a, b) ((a) < ~(size_t)(b) ? (a) + (b) : ~(size_t)0) + /* Allocate an object of size (incl. header) of size > CHUNK_SIZE. */ /* sz includes space for an AO_t-sized header. */ static char * @@ -142,9 +146,8 @@ AO_malloc_large(size_t sz) { char * result; /* The header will force us to waste ALIGNMENT bytes, incl. header. */ - sz += ALIGNMENT; - /* Round to multiple of CHUNK_SIZE. */ - sz = (sz + CHUNK_SIZE - 1) & ~(CHUNK_SIZE - 1); + /* Round to multiple of CHUNK_SIZE. */ + sz = SIZET_SAT_ADD(sz, ALIGNMENT + CHUNK_SIZE - 1) & ~(CHUNK_SIZE - 1); result = get_mmaped(sz); if (result == 0) return 0; result += ALIGNMENT; |