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always use non-flat map in secure mode and validate pointers passed to free

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daanx 2025-05-21 16:32:06 -07:00
parent 09c2b7fdcf
commit 8a66ae818a
5 changed files with 13 additions and 3 deletions
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6
include/mimalloc/bits.h
View file

@ -123,13 +123,17 @@ typedef int32_t mi_ssize_t;
// use a flat page-map (or a 2-level one)
#ifndef MI_PAGE_MAP_FLAT
#if MI_MAX_VABITS <= 40 && !defined(__APPLE__)
#if MI_MAX_VABITS <= 40 && !MI_SECURE && !defined(__APPLE__)
#define MI_PAGE_MAP_FLAT 1
#else
#define MI_PAGE_MAP_FLAT 0
#endif
#endif
#if MI_PAGE_MAP_FLAT && MI_SECURE
#error should not use MI_PAGE_MAP_FLAT with a secure build
#endif
/* --------------------------------------------------------------------------------
Builtin's

2
include/mimalloc/internal.h
View file

@ -589,7 +589,7 @@ static inline mi_page_t* _mi_checked_ptr_page(const void* p) {
static inline mi_page_t* _mi_ptr_page(const void* p) {
mi_assert_internal(p==NULL || mi_is_in_heap_region(p));
#if MI_DEBUG || defined(__APPLE__)
#if MI_DEBUG || MI_SECURE || defined(__APPLE__)
return _mi_checked_ptr_page(p);
#else
return _mi_unchecked_ptr_page(p);

2
include/mimalloc/types.h
View file

@ -50,7 +50,7 @@ terms of the MIT license. A copy of the license can be found in the file
// Define MI_SECURE to enable security mitigations. Level 1 has minimal performance impact,
// but protects most metadata with guard pages:
// #define MI_SECURE 1 // guard page around metadata
// #define MI_SECURE 1 // guard page around metadata; check pointer validity on free
//
// Level 2 has more performance impact but protect well against various buffer overflows
// by surrounding all mimalloc pages with guard pages:

4
src/page-map.c
View file

@ -202,8 +202,12 @@ bool _mi_page_map_init(void) {
const size_t page_map_size = _mi_align_up( mi_page_map_count * sizeof(mi_page_t**), os_page_size);
const size_t submap_size = MI_PAGE_MAP_SUB_SIZE;
const size_t reserve_size = page_map_size + submap_size;
#if MI_SECURE
const bool commit = true; // the whole page map is valid and we can reliably check any pointer
#else
const bool commit = page_map_size <= 64*MI_KiB ||
mi_option_is_enabled(mi_option_pagemap_commit) || _mi_os_has_overcommit();
#endif
_mi_page_map = (_Atomic(mi_page_t**)*)_mi_os_alloc_aligned(reserve_size, 1, commit, true /* allow large */, &mi_page_map_memid);
if (_mi_page_map==NULL) {
_mi_error_message(ENOMEM, "unable to reserve virtual memory for the page map (%zu KiB)\n", page_map_size / MI_KiB);

2
test/test-api.c
View file

@ -89,9 +89,11 @@ int main(void) {
CHECK_BODY("malloc-free-null") {
mi_free(NULL);
};
#if MI_INTPTR_BITS >= 64
CHECK_BODY("malloc-free-invalid-low") {
mi_free((void*)(MI_ZU(0x0000000003990080))); // issue #1087
};
#endif
CHECK_BODY("calloc-overflow") {
// use (size_t)&mi_calloc to get some number without triggering compiler warnings
result = (mi_calloc((size_t)&mi_calloc,SIZE_MAX/1000) == NULL);