From 90a80eb076429978e720e11fb17a3cbb96de3454 Mon Sep 17 00:00:00 2001 From: Peter Zhu Date: Thu, 29 Dec 2022 20:27:09 -0500 Subject: Fix integer underflow when using HEAP_INIT_SLOTS There is an integer underflow when the environment variable RUBY_GC_HEAP_INIT_SLOTS is less than the number of slots currently in the Ruby heap. [Bug #19284] --- gc.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) (limited to 'gc.c') diff --git a/gc.c b/gc.c index feeda21f44..88efedc7df 100644 --- a/gc.c +++ b/gc.c @@ -11719,24 +11719,25 @@ get_envparam_double(const char *name, double *default_value, double lower_bound, } static void -gc_set_initial_pages(void) +gc_set_initial_pages(rb_objspace_t *objspace) { - size_t min_pages; - rb_objspace_t *objspace = &rb_objspace; - gc_rest(objspace); - min_pages = gc_params.heap_init_slots / HEAP_PAGE_OBJ_LIMIT; - - size_t pages_per_class = (min_pages - heap_eden_total_pages(objspace)) / SIZE_POOL_COUNT; - for (int i = 0; i < SIZE_POOL_COUNT; i++) { rb_size_pool_t *size_pool = &size_pools[i]; - heap_add_pages(objspace, size_pool, SIZE_POOL_EDEN_HEAP(size_pool), pages_per_class); + if (gc_params.heap_init_slots > size_pool->eden_heap.total_slots) { + size_t slots = gc_params.heap_init_slots - size_pool->eden_heap.total_slots; + int multiple = size_pool->slot_size / BASE_SLOT_SIZE; + size_pool->allocatable_pages = slots * multiple / HEAP_PAGE_OBJ_LIMIT; + } + else { + /* We already have more slots than heap_init_slots allows, so + * prevent creating more pages. */ + size_pool->allocatable_pages = 0; + } } - - heap_add_pages(objspace, &size_pools[0], SIZE_POOL_EDEN_HEAP(&size_pools[0]), min_pages - heap_eden_total_pages(objspace)); + heap_pages_expand_sorted(objspace); } /* @@ -11792,7 +11793,7 @@ ruby_gc_set_params(void) /* RUBY_GC_HEAP_INIT_SLOTS */ if (get_envparam_size("RUBY_GC_HEAP_INIT_SLOTS", &gc_params.heap_init_slots, 0)) { - gc_set_initial_pages(); + gc_set_initial_pages(objspace); } get_envparam_double("RUBY_GC_HEAP_GROWTH_FACTOR", &gc_params.growth_factor, 1.0, 0.0, FALSE); -- cgit v1.2.3