From 34d37fa2048f3bd65d017bf4f295b3b5b97ae98e Mon Sep 17 00:00:00 2001 From: Daan Date: Mon, 18 Mar 2024 03:47:54 -0700 Subject: [PATCH] nicer organisation of free.c --- src/free.c | 431 +++++++++++++++++++++++++++-------------------------- 1 file changed, 222 insertions(+), 209 deletions(-) diff --git a/src/free.c b/src/free.c index 6cdac123..e7547aa3 100644 --- a/src/free.c +++ b/src/free.c @@ -8,214 +8,12 @@ terms of the MIT license. A copy of the license can be found in the file #error "this file should be included from 'alloc.c' (so aliases can work from alloc-override)" #endif -// ------------------------------------------------------ -// Check for double free in secure and debug mode -// This is somewhat expensive so only enabled for secure mode 4 -// ------------------------------------------------------ +// forward declarations +static void mi_check_padding(const mi_page_t* page, const mi_block_t* block); +static bool mi_check_is_double_free(const mi_page_t* page, const mi_block_t* block); +static size_t mi_page_usable_size_of(const mi_page_t* page, const mi_block_t* block); +static void mi_stat_free(const mi_page_t* page, const mi_block_t* block); -#if (MI_ENCODE_FREELIST && (MI_SECURE>=4 || MI_DEBUG!=0)) -// linear check if the free list contains a specific element -static bool mi_list_contains(const mi_page_t* page, const mi_block_t* list, const mi_block_t* elem) { - while (list != NULL) { - if (elem==list) return true; - list = mi_block_next(page, list); - } - return false; -} - -static mi_decl_noinline bool mi_check_is_double_freex(const mi_page_t* page, const mi_block_t* block) { - // The decoded value is in the same page (or NULL). - // Walk the free lists to verify positively if it is already freed - if (mi_list_contains(page, page->free, block) || - mi_list_contains(page, page->local_free, block) || - mi_list_contains(page, mi_page_thread_free(page), block)) - { - _mi_error_message(EAGAIN, "double free detected of block %p with size %zu\n", block, mi_page_block_size(page)); - return true; - } - return false; -} - -#define mi_track_page(page,access) { size_t psize; void* pstart = _mi_page_start(_mi_page_segment(page),page,&psize); mi_track_mem_##access( pstart, psize); } - -static inline bool mi_check_is_double_free(const mi_page_t* page, const mi_block_t* block) { - bool is_double_free = false; - mi_block_t* n = mi_block_nextx(page, block, page->keys); // pretend it is freed, and get the decoded first field - if (((uintptr_t)n & (MI_INTPTR_SIZE-1))==0 && // quick check: aligned pointer? - (n==NULL || mi_is_in_same_page(block, n))) // quick check: in same page or NULL? - { - // Suspicous: decoded value a in block is in the same page (or NULL) -- maybe a double free? - // (continue in separate function to improve code generation) - is_double_free = mi_check_is_double_freex(page, block); - } - return is_double_free; -} -#else -static inline bool mi_check_is_double_free(const mi_page_t* page, const mi_block_t* block) { - MI_UNUSED(page); - MI_UNUSED(block); - return false; -} -#endif - -// --------------------------------------------------------------------------- -// Check for heap block overflow by setting up padding at the end of the block -// --------------------------------------------------------------------------- - -#if MI_PADDING // && !MI_TRACK_ENABLED -static bool mi_page_decode_padding(const mi_page_t* page, const mi_block_t* block, size_t* delta, size_t* bsize) { - *bsize = mi_page_usable_block_size(page); - const mi_padding_t* const padding = (mi_padding_t*)((uint8_t*)block + *bsize); - mi_track_mem_defined(padding,sizeof(mi_padding_t)); - *delta = padding->delta; - uint32_t canary = padding->canary; - uintptr_t keys[2]; - keys[0] = page->keys[0]; - keys[1] = page->keys[1]; - bool ok = ((uint32_t)mi_ptr_encode(page,block,keys) == canary && *delta <= *bsize); - mi_track_mem_noaccess(padding,sizeof(mi_padding_t)); - return ok; -} - -// Return the exact usable size of a block. -static size_t mi_page_usable_size_of(const mi_page_t* page, const mi_block_t* block) { - size_t bsize; - size_t delta; - bool ok = mi_page_decode_padding(page, block, &delta, &bsize); - mi_assert_internal(ok); mi_assert_internal(delta <= bsize); - return (ok ? bsize - delta : 0); -} - -// When a non-thread-local block is freed, it becomes part of the thread delayed free -// list that is freed later by the owning heap. If the exact usable size is too small to -// contain the pointer for the delayed list, then shrink the padding (by decreasing delta) -// so it will later not trigger an overflow error in `mi_free_block`. -void _mi_padding_shrink(const mi_page_t* page, const mi_block_t* block, const size_t min_size) { - size_t bsize; - size_t delta; - bool ok = mi_page_decode_padding(page, block, &delta, &bsize); - mi_assert_internal(ok); - if (!ok || (bsize - delta) >= min_size) return; // usually already enough space - mi_assert_internal(bsize >= min_size); - if (bsize < min_size) return; // should never happen - size_t new_delta = (bsize - min_size); - mi_assert_internal(new_delta < bsize); - mi_padding_t* padding = (mi_padding_t*)((uint8_t*)block + bsize); - mi_track_mem_defined(padding,sizeof(mi_padding_t)); - padding->delta = (uint32_t)new_delta; - mi_track_mem_noaccess(padding,sizeof(mi_padding_t)); -} -#else -static size_t mi_page_usable_size_of(const mi_page_t* page, const mi_block_t* block) { - MI_UNUSED(block); - return mi_page_usable_block_size(page); -} - -void _mi_padding_shrink(const mi_page_t* page, const mi_block_t* block, const size_t min_size) { - MI_UNUSED(page); - MI_UNUSED(block); - MI_UNUSED(min_size); -} -#endif - -#if MI_PADDING && MI_PADDING_CHECK - -static bool mi_verify_padding(const mi_page_t* page, const mi_block_t* block, size_t* size, size_t* wrong) { - size_t bsize; - size_t delta; - bool ok = mi_page_decode_padding(page, block, &delta, &bsize); - *size = *wrong = bsize; - if (!ok) return false; - mi_assert_internal(bsize >= delta); - *size = bsize - delta; - if (!mi_page_is_huge(page)) { - uint8_t* fill = (uint8_t*)block + bsize - delta; - const size_t maxpad = (delta > MI_MAX_ALIGN_SIZE ? MI_MAX_ALIGN_SIZE : delta); // check at most the first N padding bytes - mi_track_mem_defined(fill, maxpad); - for (size_t i = 0; i < maxpad; i++) { - if (fill[i] != MI_DEBUG_PADDING) { - *wrong = bsize - delta + i; - ok = false; - break; - } - } - mi_track_mem_noaccess(fill, maxpad); - } - return ok; -} - -static void mi_check_padding(const mi_page_t* page, const mi_block_t* block) { - size_t size; - size_t wrong; - if (!mi_verify_padding(page,block,&size,&wrong)) { - _mi_error_message(EFAULT, "buffer overflow in heap block %p of size %zu: write after %zu bytes\n", block, size, wrong ); - } -} - -#else - -static void mi_check_padding(const mi_page_t* page, const mi_block_t* block) { - MI_UNUSED(page); - MI_UNUSED(block); -} - -#endif - -// only maintain stats for smaller objects if requested -#if (MI_STAT>0) -static void mi_stat_free(const mi_page_t* page, const mi_block_t* block) { -#if (MI_STAT < 2) - MI_UNUSED(block); -#endif - mi_heap_t* const heap = mi_heap_get_default(); - const size_t bsize = mi_page_usable_block_size(page); -#if (MI_STAT>1) - const size_t usize = mi_page_usable_size_of(page, block); - mi_heap_stat_decrease(heap, malloc, usize); -#endif - if (bsize <= MI_LARGE_OBJ_SIZE_MAX) { - mi_heap_stat_decrease(heap, normal, bsize); -#if (MI_STAT > 1) - mi_heap_stat_decrease(heap, normal_bins[_mi_bin(bsize)], 1); -#endif - } -#if !MI_HUGE_PAGE_ABANDON - else { - const size_t bpsize = mi_page_block_size(page); - if (bpsize <= MI_HUGE_OBJ_SIZE_MAX) { - mi_heap_stat_decrease(heap, huge, bpsize); - } - else { - mi_heap_stat_decrease(heap, giant, bpsize); - } - } -#endif -} -#else -static void mi_stat_free(const mi_page_t* page, const mi_block_t* block) { - MI_UNUSED(page); MI_UNUSED(block); -} -#endif - -#if MI_HUGE_PAGE_ABANDON -#if (MI_STAT>0) -// maintain stats for huge objects -static void mi_stat_huge_free(const mi_page_t* page) { - mi_heap_t* const heap = mi_heap_get_default(); - const size_t bsize = mi_page_block_size(page); // to match stats in `page.c:mi_page_huge_alloc` - if (bsize <= MI_HUGE_OBJ_SIZE_MAX) { - mi_heap_stat_decrease(heap, huge, bsize); - } - else { - mi_heap_stat_decrease(heap, giant, bsize); - } -} -#else -static void mi_stat_huge_free(const mi_page_t* page) { - MI_UNUSED(page); -} -#endif -#endif // ------------------------------------------------------ // Free @@ -417,8 +215,12 @@ static void mi_decl_noinline mi_free_block_delayed_mt( mi_page_t* page, mi_block } } +#if MI_HUGE_PAGE_ABANDON +static void mi_stat_huge_free(const mi_page_t* page); +#endif + // Multi-threaded free (`_mt`) (or free in huge block if compiled with MI_HUGE_PAGE_ABANDON) -static mi_decl_noinline void mi_free_block_mt(mi_segment_t* segment, mi_page_t* page, mi_block_t* block) +static void mi_decl_noinline mi_free_block_mt(mi_segment_t* segment, mi_page_t* page, mi_block_t* block) { // first see if the segment was abandoned and if we can reclaim it into our thread if (mi_option_is_enabled(mi_option_abandoned_reclaim_on_free) && @@ -504,7 +306,7 @@ mi_decl_nodiscard size_t mi_usable_size(const void* p) mi_attr_noexcept { // ------------------------------------------------------ -// Allocation extensions +// Free variants // ------------------------------------------------------ void mi_free_size(void* p, size_t size) mi_attr_noexcept { @@ -524,3 +326,214 @@ void mi_free_aligned(void* p, size_t alignment) mi_attr_noexcept { mi_assert(((uintptr_t)p % alignment) == 0); mi_free(p); } + + +// ------------------------------------------------------ +// Check for double free in secure and debug mode +// This is somewhat expensive so only enabled for secure mode 4 +// ------------------------------------------------------ + +#if (MI_ENCODE_FREELIST && (MI_SECURE>=4 || MI_DEBUG!=0)) +// linear check if the free list contains a specific element +static bool mi_list_contains(const mi_page_t* page, const mi_block_t* list, const mi_block_t* elem) { + while (list != NULL) { + if (elem==list) return true; + list = mi_block_next(page, list); + } + return false; +} + +static mi_decl_noinline bool mi_check_is_double_freex(const mi_page_t* page, const mi_block_t* block) { + // The decoded value is in the same page (or NULL). + // Walk the free lists to verify positively if it is already freed + if (mi_list_contains(page, page->free, block) || + mi_list_contains(page, page->local_free, block) || + mi_list_contains(page, mi_page_thread_free(page), block)) + { + _mi_error_message(EAGAIN, "double free detected of block %p with size %zu\n", block, mi_page_block_size(page)); + return true; + } + return false; +} + +#define mi_track_page(page,access) { size_t psize; void* pstart = _mi_page_start(_mi_page_segment(page),page,&psize); mi_track_mem_##access( pstart, psize); } + +static inline bool mi_check_is_double_free(const mi_page_t* page, const mi_block_t* block) { + bool is_double_free = false; + mi_block_t* n = mi_block_nextx(page, block, page->keys); // pretend it is freed, and get the decoded first field + if (((uintptr_t)n & (MI_INTPTR_SIZE-1))==0 && // quick check: aligned pointer? + (n==NULL || mi_is_in_same_page(block, n))) // quick check: in same page or NULL? + { + // Suspicous: decoded value a in block is in the same page (or NULL) -- maybe a double free? + // (continue in separate function to improve code generation) + is_double_free = mi_check_is_double_freex(page, block); + } + return is_double_free; +} +#else +static inline bool mi_check_is_double_free(const mi_page_t* page, const mi_block_t* block) { + MI_UNUSED(page); + MI_UNUSED(block); + return false; +} +#endif + + +// --------------------------------------------------------------------------- +// Check for heap block overflow by setting up padding at the end of the block +// --------------------------------------------------------------------------- + +#if MI_PADDING // && !MI_TRACK_ENABLED +static bool mi_page_decode_padding(const mi_page_t* page, const mi_block_t* block, size_t* delta, size_t* bsize) { + *bsize = mi_page_usable_block_size(page); + const mi_padding_t* const padding = (mi_padding_t*)((uint8_t*)block + *bsize); + mi_track_mem_defined(padding,sizeof(mi_padding_t)); + *delta = padding->delta; + uint32_t canary = padding->canary; + uintptr_t keys[2]; + keys[0] = page->keys[0]; + keys[1] = page->keys[1]; + bool ok = ((uint32_t)mi_ptr_encode(page,block,keys) == canary && *delta <= *bsize); + mi_track_mem_noaccess(padding,sizeof(mi_padding_t)); + return ok; +} + +// Return the exact usable size of a block. +static size_t mi_page_usable_size_of(const mi_page_t* page, const mi_block_t* block) { + size_t bsize; + size_t delta; + bool ok = mi_page_decode_padding(page, block, &delta, &bsize); + mi_assert_internal(ok); mi_assert_internal(delta <= bsize); + return (ok ? bsize - delta : 0); +} + +// When a non-thread-local block is freed, it becomes part of the thread delayed free +// list that is freed later by the owning heap. If the exact usable size is too small to +// contain the pointer for the delayed list, then shrink the padding (by decreasing delta) +// so it will later not trigger an overflow error in `mi_free_block`. +void _mi_padding_shrink(const mi_page_t* page, const mi_block_t* block, const size_t min_size) { + size_t bsize; + size_t delta; + bool ok = mi_page_decode_padding(page, block, &delta, &bsize); + mi_assert_internal(ok); + if (!ok || (bsize - delta) >= min_size) return; // usually already enough space + mi_assert_internal(bsize >= min_size); + if (bsize < min_size) return; // should never happen + size_t new_delta = (bsize - min_size); + mi_assert_internal(new_delta < bsize); + mi_padding_t* padding = (mi_padding_t*)((uint8_t*)block + bsize); + mi_track_mem_defined(padding,sizeof(mi_padding_t)); + padding->delta = (uint32_t)new_delta; + mi_track_mem_noaccess(padding,sizeof(mi_padding_t)); +} +#else +static size_t mi_page_usable_size_of(const mi_page_t* page, const mi_block_t* block) { + MI_UNUSED(block); + return mi_page_usable_block_size(page); +} + +void _mi_padding_shrink(const mi_page_t* page, const mi_block_t* block, const size_t min_size) { + MI_UNUSED(page); + MI_UNUSED(block); + MI_UNUSED(min_size); +} +#endif + +#if MI_PADDING && MI_PADDING_CHECK + +static bool mi_verify_padding(const mi_page_t* page, const mi_block_t* block, size_t* size, size_t* wrong) { + size_t bsize; + size_t delta; + bool ok = mi_page_decode_padding(page, block, &delta, &bsize); + *size = *wrong = bsize; + if (!ok) return false; + mi_assert_internal(bsize >= delta); + *size = bsize - delta; + if (!mi_page_is_huge(page)) { + uint8_t* fill = (uint8_t*)block + bsize - delta; + const size_t maxpad = (delta > MI_MAX_ALIGN_SIZE ? MI_MAX_ALIGN_SIZE : delta); // check at most the first N padding bytes + mi_track_mem_defined(fill, maxpad); + for (size_t i = 0; i < maxpad; i++) { + if (fill[i] != MI_DEBUG_PADDING) { + *wrong = bsize - delta + i; + ok = false; + break; + } + } + mi_track_mem_noaccess(fill, maxpad); + } + return ok; +} + +static void mi_check_padding(const mi_page_t* page, const mi_block_t* block) { + size_t size; + size_t wrong; + if (!mi_verify_padding(page,block,&size,&wrong)) { + _mi_error_message(EFAULT, "buffer overflow in heap block %p of size %zu: write after %zu bytes\n", block, size, wrong ); + } +} + +#else + +static void mi_check_padding(const mi_page_t* page, const mi_block_t* block) { + MI_UNUSED(page); + MI_UNUSED(block); +} + +#endif + +// only maintain stats for smaller objects if requested +#if (MI_STAT>0) +static void mi_stat_free(const mi_page_t* page, const mi_block_t* block) { +#if (MI_STAT < 2) + MI_UNUSED(block); +#endif + mi_heap_t* const heap = mi_heap_get_default(); + const size_t bsize = mi_page_usable_block_size(page); +#if (MI_STAT>1) + const size_t usize = mi_page_usable_size_of(page, block); + mi_heap_stat_decrease(heap, malloc, usize); +#endif + if (bsize <= MI_LARGE_OBJ_SIZE_MAX) { + mi_heap_stat_decrease(heap, normal, bsize); +#if (MI_STAT > 1) + mi_heap_stat_decrease(heap, normal_bins[_mi_bin(bsize)], 1); +#endif + } +#if !MI_HUGE_PAGE_ABANDON + else { + const size_t bpsize = mi_page_block_size(page); + if (bpsize <= MI_HUGE_OBJ_SIZE_MAX) { + mi_heap_stat_decrease(heap, huge, bpsize); + } + else { + mi_heap_stat_decrease(heap, giant, bpsize); + } + } +#endif +} +#else +static void mi_stat_free(const mi_page_t* page, const mi_block_t* block) { + MI_UNUSED(page); MI_UNUSED(block); +} +#endif + +#if MI_HUGE_PAGE_ABANDON +#if (MI_STAT>0) +// maintain stats for huge objects +static void mi_stat_huge_free(const mi_page_t* page) { + mi_heap_t* const heap = mi_heap_get_default(); + const size_t bsize = mi_page_block_size(page); // to match stats in `page.c:mi_page_huge_alloc` + if (bsize <= MI_HUGE_OBJ_SIZE_MAX) { + mi_heap_stat_decrease(heap, huge, bsize); + } + else { + mi_heap_stat_decrease(heap, giant, bsize); + } +} +#else +static void mi_stat_huge_free(const mi_page_t* page) { + MI_UNUSED(page); +} +#endif +#endif