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fix guarded sample rate of 1 (issue #1085)

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daanx 2025-05-13 15:58:45 -07:00
parent a6ecb5c299
commit 72f05e2f07
3 changed files with 9 additions and 11 deletions
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1
include/mimalloc/types.h
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@ -512,7 +512,6 @@ struct mi_heap_s {
size_t guarded_size_min; // minimal size for guarded objects
size_t guarded_size_max; // maximal size for guarded objects
size_t guarded_sample_rate; // sample rate (set to 0 to disable guarded pages)
size_t guarded_sample_seed; // starting sample count
size_t guarded_sample_count; // current sample count (counting down to 0)
#endif
mi_page_t* pages_free_direct[MI_PAGES_DIRECT]; // optimize: array where every entry points a page with possibly free blocks in the corresponding queue for that size.

17
src/init.c
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@ -110,7 +110,7 @@ mi_decl_cache_align const mi_heap_t _mi_heap_empty = {
false, // can reclaim
0, // tag
#if MI_GUARDED
0, 0, 0, 0, 1, // count is 1 so we never write to it (see `internal.h:mi_heap_malloc_use_guarded`)
0, 0, 0, 1, // count is 1 so we never write to it (see `internal.h:mi_heap_malloc_use_guarded`)
#endif
MI_SMALL_PAGES_EMPTY,
MI_PAGE_QUEUES_EMPTY
@ -153,7 +153,7 @@ mi_decl_cache_align mi_heap_t _mi_heap_main = {
false, // can reclaim
0, // tag
#if MI_GUARDED
0, 0, 0, 0, 0,
0, 0, 0, 0,
#endif
MI_SMALL_PAGES_EMPTY,
MI_PAGE_QUEUES_EMPTY
@ -165,15 +165,14 @@ mi_stats_t _mi_stats_main = { MI_STAT_VERSION, MI_STATS_NULL };
#if MI_GUARDED
mi_decl_export void mi_heap_guarded_set_sample_rate(mi_heap_t* heap, size_t sample_rate, size_t seed) {
heap->guarded_sample_seed = seed;
if (heap->guarded_sample_seed == 0) {
heap->guarded_sample_seed = _mi_heap_random_next(heap);
}
heap->guarded_sample_rate = sample_rate;
if (heap->guarded_sample_rate >= 1) {
heap->guarded_sample_seed = heap->guarded_sample_seed % heap->guarded_sample_rate;
heap->guarded_sample_count = sample_rate; // count down samples
if (heap->guarded_sample_rate > 1) {
if (seed == 0) {
seed = _mi_heap_random_next(heap);
}
heap->guarded_sample_count = (seed % heap->guarded_sample_rate) + 1; // start at random count between 1 and `sample_rate`
}
heap->guarded_sample_count = heap->guarded_sample_seed; // count down samples
}
mi_decl_export void mi_heap_guarded_set_size_bound(mi_heap_t* heap, size_t min, size_t max) {

2
test/main-override-static.c
View file

@ -43,7 +43,7 @@ int main() {
// corrupt_free();
// block_overflow1();
// block_overflow2();
// test_canary_leak();
test_canary_leak();
// test_aslr();
// invalid_free();
// test_reserved();