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--- /dev/null
+++ libmalloc/libmalloc-409.81.2/src/pgm_malloc.c
@@ -0,0 +1,1695 @@
+/*
+ * Copyright (c) 2020 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include "pgm_malloc.h"
+
+#include <TargetConditionals.h>
+#if !TARGET_OS_DRIVERKIT
+# include <dlfcn.h> // dladdr()
+#endif
+#include <mach/mach_time.h> // mach_absolute_time()
+#include <sys/codesign.h> // csops()
+
+#include "internal.h"
+
+
+#pragma mark -
+#pragma mark Types and Structures
+
+static const char * const slot_state_labels[] = {
+ "unused", "allocated", "freed"
+};
+
+typedef enum {
+ ss_unused,
+ ss_allocated,
+ ss_freed
+} slot_state_t;
+
+MALLOC_STATIC_ASSERT(ss_unused == 0, "unused encoded with 0");
+MALLOC_STATIC_ASSERT(ss_freed < (1 << 2), "enum encodable with 2 bits");
+
+typedef struct {
+ slot_state_t state : 2;
+ uint32_t metadata : 30; // metadata << slots, so borrowing 2 bits here is okay.
+ uint16_t size;
+ uint16_t offset;
+} slot_t;
+
+MALLOC_STATIC_ASSERT(PAGE_MAX_SIZE <= UINT16_MAX, "16 bits for page offsets");
+MALLOC_STATIC_ASSERT(sizeof(slot_t) == 8, "slot_t size");
+
+typedef struct MALLOC_PACKED {
+ uint64_t thread_id;
+ uint64_t time;
+ uint16_t trace_size;
+} alloc_info_t;
+
+MALLOC_STATIC_ASSERT(sizeof(alloc_info_t) == 18, "alloc_info_t size (packed)");
+
+typedef struct {
+ uint32_t slot;
+ alloc_info_t alloc;
+ alloc_info_t dealloc;
+ uint8_t trace_buffer[216]; // ~62 frames (~3.5 bytes per 8-byte pointer)
+} metadata_t;
+
+MALLOC_STATIC_ASSERT(sizeof(((metadata_t *)NULL)->trace_buffer) <= UINT16_MAX,
+ "16 bits for trace buffer size");
+MALLOC_STATIC_ASSERT(sizeof(metadata_t) == 256, "metadata_t size");
+
+typedef struct {
+ // Malloc zone
+ malloc_zone_t malloc_zone;
+ malloc_zone_t *wrapped_zone;
+
+ // Configuration
+ uint32_t num_slots;
+ uint32_t max_allocations;
+ uint32_t max_metadata;
+ uint32_t sample_counter_range;
+ uint32_t min_alignment;
+ bool signal_handler;
+ bool debug;
+ uint64_t debug_log_throttle_ms;
+
+ // Quarantine
+ size_t size;
+ vm_address_t begin;
+ vm_address_t end;
+ size_t region_size;
+ vm_address_t region_begin;
+
+ // Metadata
+ slot_t *slots;
+ metadata_t *metadata;
+ uint8_t padding[PAGE_MAX_SIZE];
+
+ // Mutable state
+ _malloc_lock_s lock;
+ uint32_t num_allocations;
+ uint32_t num_metadata;
+ uint32_t rr_slot_index;
+
+ // Statistics
+ size_t size_in_use;
+ size_t max_size_in_use;
+ uint64_t last_log_time;
+} pgm_zone_t;
+
+MALLOC_STATIC_ASSERT(__offsetof(pgm_zone_t, malloc_zone) == 0,
+ "pgm_zone_t instances must be usable as regular zones");
+MALLOC_STATIC_ASSERT(__offsetof(pgm_zone_t, padding) < PAGE_MAX_SIZE,
+ "First page is mapped read-only");
+MALLOC_STATIC_ASSERT(__offsetof(pgm_zone_t, lock) >= PAGE_MAX_SIZE,
+ "Mutable state is on separate page");
+MALLOC_STATIC_ASSERT(sizeof(pgm_zone_t) < (2 * PAGE_MAX_SIZE),
+ "Zone fits on 2 pages");
+
+
+#pragma mark -
+#pragma mark Thread Local Sample Counter
+
+MALLOC_STATIC_ASSERT(sizeof(void *) >= sizeof(uint32_t), "Pointer is used as 32bit counter");
+
+#define TSD_GET_COUNTER() ((uint32_t)_pthread_getspecific_direct(__TSD_MALLOC_PROB_GUARD_SAMPLE_COUNTER))
+#define TSD_SET_COUNTER(val) _pthread_setspecific_direct(__TSD_MALLOC_PROB_GUARD_SAMPLE_COUNTER, (void *)(uintptr_t)val)
+
+static const uint32_t k_no_sample = UINT32_MAX;
+
+void
+pgm_disable_for_current_thread(void)
+{
+ malloc_thread_options_t opts = {.DisableExpensiveDebuggingOptions = true};
+ malloc_set_thread_options(opts);
+}
+
+void
+pgm_thread_set_disabled(bool disabled)
+{
+ if (disabled) {
+ TSD_SET_COUNTER(k_no_sample);
+ } else {
+ TSD_SET_COUNTER(0);
+ }
+}
+
+
+#pragma mark -
+#pragma mark Decider Functions
+
+// The "decider" functions are performance critical. They should be inlinable and must not lock.
+
+MALLOC_ALWAYS_INLINE
+static inline boolean_t
+is_full(const pgm_zone_t *zone)
+{
+ return zone->num_allocations == zone->max_allocations;
+}
+
+static uint32_t rand_uniform(uint32_t upper_bound);
+
+#ifndef PGM_MOCK_SHOULD_SAMPLE_COUNTER
+MALLOC_ALWAYS_INLINE
+static inline boolean_t
+should_sample_counter(uint32_t counter_range)
+{
+ uint32_t counter = TSD_GET_COUNTER();
+ if (counter == k_no_sample) {
+ return false;
+ }
+ // 0 -> regenerate counter; 1 -> sample allocation
+ if (counter == 0) {
+ counter = rand_uniform(counter_range);
+ } else {
+ counter--;
+ }
+ TSD_SET_COUNTER(counter);
+ return counter == 0;
+}
+#endif
+
+MALLOC_ALWAYS_INLINE
+static inline boolean_t
+should_sample(pgm_zone_t *zone, size_t size)
+{
+ boolean_t good_size = (size <= PAGE_SIZE);
+ boolean_t not_full = !is_full(zone); // Optimization: racy check; we check again in allocate() for correctness.
+ return good_size && not_full && should_sample_counter(zone->sample_counter_range);
+}
+
+MALLOC_ALWAYS_INLINE
+static inline boolean_t
+is_guarded(const pgm_zone_t *zone, vm_address_t addr)
+{
+ return zone->begin <= addr && addr < zone->end;
+}
+
+
+#pragma mark -
+#pragma mark Slot <-> Address Mapping
+
+// Prevent overflows on 32 bit platforms (sizeof(size_t) == sizeof(uint32_t)).
+static const uint32_t k_max_slots = (MALLOC_TARGET_64BIT) ?
+ UINT32_MAX :
+ (UINT32_MAX / PAGE_MAX_SIZE - 1) / 2; // reverse of quarantine_size()
+
+static size_t
+quarantine_size(uint32_t num_slots)
+{
+ MALLOC_ASSERT(num_slots <= k_max_slots);
+ return (2 * num_slots + 1) * PAGE_SIZE;
+}
+
+static vm_address_t
+page_addr(const pgm_zone_t *zone, uint32_t slot)
+{
+ MALLOC_ASSERT(slot < zone->num_slots);
+ uint32_t page = 1 + 2 * slot;
+ vm_offset_t offset = page * PAGE_SIZE;
+ return zone->begin + offset;
+}
+
+static vm_address_t
+block_addr(const pgm_zone_t *zone, uint32_t slot) {
+ vm_address_t page = page_addr(zone, slot);
+ uint16_t offset = zone->slots[slot].offset;
+ return page + offset;
+}
+
+static uint32_t
+page_idx(const pgm_zone_t *zone, vm_address_t addr)
+{
+ MALLOC_ASSERT(is_guarded(zone, addr));
+ vm_offset_t offset = addr - zone->begin;
+ return (uint32_t)(offset / PAGE_SIZE);
+}
+
+static boolean_t
+is_guard_page(const pgm_zone_t *zone, vm_address_t addr)
+{
+ return page_idx(zone, addr) % 2 == 0;
+}
+
+
+#pragma mark -
+#pragma mark Slot Lookup
+
+static uint32_t
+nearest_slot(const pgm_zone_t *zone, vm_address_t addr)
+{
+ if (addr < (zone->begin + PAGE_SIZE)) {
+ return 0;
+ }
+ if (addr >= (zone->end - PAGE_SIZE)) {
+ return zone->num_slots - 1;
+ }
+
+ uint32_t page = page_idx(zone, addr);
+ uint32_t slot = (page - 1) / 2;
+ boolean_t guard_page = is_guard_page(zone, addr);
+ boolean_t right_half = ((addr % PAGE_SIZE) >= (PAGE_SIZE / 2));
+
+ if (guard_page && right_half) {
+ slot++; // Round up.
+ }
+ return slot;
+}
+
+typedef enum {
+ b_block_addr, // Canonical block address.
+ b_valid, // Address within block.
+ b_oob_slot, // Outside block, but within slot.
+ b_oob_guard_page // Guard page.
+} bounds_status_t;
+
+typedef struct {
+ uint32_t slot;
+ bounds_status_t bounds : 31;
+ boolean_t live_block_addr : 1; // Canonical block address for live allocation.
+} slot_lookup_t;
+
+MALLOC_STATIC_ASSERT(sizeof(slot_lookup_t) == 8, "slot_lookup_t size");
+
+static slot_lookup_t
+lookup_slot(const pgm_zone_t *zone, vm_address_t addr)
+{
+ MALLOC_ASSERT(is_guarded(zone, addr));
+ MALLOC_ASSERT(zone->begin % PAGE_SIZE == 0);
+
+ uint32_t slot = nearest_slot(zone, addr);
+ uint16_t offset = (addr % PAGE_SIZE);
+ uint16_t begin = zone->slots[slot].offset;
+ uint16_t end = begin + zone->slots[slot].size;
+
+ bounds_status_t bounds;
+ if (is_guard_page(zone, addr)) {
+ bounds = b_oob_guard_page;
+ } else if (offset == begin) {
+ bounds = b_block_addr;
+ } else if (begin < offset && offset < end) {
+ bounds = b_valid;
+ } else {
+ bounds = b_oob_slot;
+ }
+
+ boolean_t live_slot = (zone->slots[slot].state == ss_allocated);
+ return (slot_lookup_t){
+ .slot = slot,
+ .bounds = bounds,
+ .live_block_addr = (live_slot && bounds == b_block_addr)
+ };
+}
+
+
+#pragma mark -
+#pragma mark Allocator Helpers
+
+static bool
+is_power_of_2(size_t n) {
+ return __builtin_popcountl(n) == 1;
+}
+
+static size_t
+block_size(size_t size, size_t min_alignment)
+{
+ MALLOC_ASSERT(is_power_of_2(min_alignment));
+ if (size == 0) {
+ return min_alignment;
+ }
+ const size_t mask = (min_alignment - 1);
+ return (size + mask) & ~mask;
+}
+
+// Current implementation: round-robin; delays reuse until at least (num_slots - max_allocations).
+// Possible alternatives: LRU, random.
+static uint32_t
+choose_available_slot(pgm_zone_t *zone)
+{
+ uint32_t slot = zone->rr_slot_index;
+ while (zone->slots[slot].state == ss_allocated) {
+ slot = (slot + 1) % zone->num_slots;
+ }
+ // Delay reuse if immediately freed.
+ zone->rr_slot_index = (slot + 1) % zone->num_slots;
+ return slot;
+}
+
+static uint32_t
+choose_metadata(pgm_zone_t *zone, uint32_t slot)
+{
+ if (zone->num_metadata < zone->max_metadata) {
+ return zone->num_metadata++;
+ }
+
+ uint32_t old_index = zone->slots[slot].metadata;
+ if (zone->metadata[old_index].slot == slot) {
+ return old_index;
+ }
+
+ while (true) {
+ uint32_t index = rand_uniform(zone->max_metadata);
+ uint32_t s = zone->metadata[index].slot;
+ if (zone->slots[s].state == ss_freed) {
+ return index;
+ }
+ }
+}
+
+static uint16_t
+choose_offset_on_page(size_t size, size_t alignment, uint16_t page_size) {
+ MALLOC_ASSERT(size <= page_size);
+ MALLOC_ASSERT(alignment <= page_size && is_power_of_2(alignment));
+ MALLOC_ASSERT(is_power_of_2(page_size));
+ boolean_t left_align = rand_uniform(2);
+ if (left_align) {
+ return 0;
+ }
+ size_t mask = ~(alignment - 1);
+ return (page_size - size) & mask;
+}
+
+MALLOC_ALWAYS_INLINE
+static inline size_t my_trace_collect(uint8_t *buffer, size_t size);
+
+MALLOC_ALWAYS_INLINE
+static inline void capture_trace(metadata_t *metadata, bool alloc)
+{
+ alloc_info_t *info = alloc ? &metadata->alloc : &metadata->dealloc;
+ info->thread_id = _pthread_threadid_self_np_direct();
+ info->time = mach_absolute_time();
+
+ size_t offset;
+ if (alloc) {
+ offset = 0;
+ metadata->dealloc = (alloc_info_t){};
+ } else {
+ offset = MIN(metadata->alloc.trace_size, sizeof(metadata->trace_buffer) / 2);
+ metadata->alloc.trace_size = offset;
+ }
+ uint8_t *buffer = &metadata->trace_buffer[offset];
+ size_t size = sizeof(metadata->trace_buffer) - offset;
+ info->trace_size = my_trace_collect(buffer, size);
+}
+
+
+#pragma mark -
+#pragma mark Allocator Functions
+
+static void mark_inaccessible(vm_address_t page);
+static void mark_read_write(vm_address_t page);
+static void debug_zone(pgm_zone_t *zone, const char *label, vm_address_t addr);
+
+// Note: the functions below require locking.
+
+static size_t
+lookup_size(pgm_zone_t *zone, vm_address_t addr)
+{
+ slot_lookup_t res = lookup_slot(zone, addr);
+ if (!res.live_block_addr) {
+ return 0;
+ }
+ return zone->slots[res.slot].size;
+}
+
+static vm_address_t
+allocate(pgm_zone_t *zone, size_t size, size_t alignment)
+{
+ MALLOC_ASSERT(size <= PAGE_SIZE);
+ MALLOC_ASSERT(zone->min_alignment <= alignment && alignment <= PAGE_SIZE);
+ MALLOC_ASSERT(is_power_of_2(alignment));
+
+ if (is_full(zone)) {
+ return (vm_address_t)NULL;
+ }
+
+ size = block_size(size, zone->min_alignment);
+ uint32_t slot = choose_available_slot(zone);
+ uint32_t metadata = choose_metadata(zone, slot);
+ uint16_t offset = choose_offset_on_page(size, alignment, PAGE_SIZE);
+
+ // Mark page writable before updating metadata. Ensures metadata is correct
+ // whenever a fault could be triggered.
+ vm_address_t page = page_addr(zone, slot);
+ mark_read_write(page);
+
+ zone->slots[slot] = (slot_t){
+ .state = ss_allocated,
+ .metadata = metadata,
+ .size = size,
+ .offset = offset
+ };
+ zone->metadata[metadata].slot = slot;
+ capture_trace(&zone->metadata[metadata], /*alloc=*/true);
+
+ zone->num_allocations++;
+ zone->size_in_use += size;
+ zone->max_size_in_use = MAX(zone->size_in_use, zone->max_size_in_use);
+
+ vm_address_t addr = page + offset;
+ debug_zone(zone, "allocated", addr);
+
+ return addr;
+}
+
+static void
+deallocate(pgm_zone_t *zone, vm_address_t addr)
+{
+ slot_lookup_t res = lookup_slot(zone, addr);
+ if (!res.live_block_addr) {
+ // TODO(yln): error report; TODO(yln): distinguish between most likely cause
+ // corrupted pointer (unused, *) or (*, !block_ptr) and double free (freed, block_ptr)
+ MALLOC_REPORT_FATAL_ERROR(addr, "ProbGuard: invalid pointer passed to free");
+ }
+
+ uint32_t slot = res.slot;
+ uint32_t metadata = zone->slots[slot].metadata;
+
+ zone->slots[slot].state = ss_freed;
+ capture_trace(&zone->metadata[metadata], /*alloc=*/false);
+
+ zone->num_allocations--;
+ zone->size_in_use -= zone->slots[slot].size;
+
+ // Mark page inaccessible after updating metadata. Ensures metadata is
+ // correct whenever a fault could be triggered.
+ vm_address_t page = page_addr(zone, slot);
+ mark_inaccessible(page);
+
+ debug_zone(zone, "freed", addr);
+}
+
+#define DELEGATE(function, args...) \
+ zone->wrapped_zone->function(zone->wrapped_zone, args)
+
+static vm_address_t
+reallocate(pgm_zone_t *zone, vm_address_t addr, size_t new_size, boolean_t sample)
+{
+ boolean_t guarded = is_guarded(zone, addr);
+ // Note: should_sample() is stateful.
+ MALLOC_ASSERT(guarded || sample);
+
+ size_t size;
+ if (guarded) {
+ size = lookup_size(zone, addr);
+ } else {
+ size = DELEGATE(size, (void *)addr);
+ }
+ if (!size) {
+ // TODO(yln): error report
+ MALLOC_REPORT_FATAL_ERROR(addr, "ProbGuard: invalid pointer passed to realloc");
+ }
+
+ vm_address_t new_addr;
+ if (sample && !is_full(zone)) {
+ new_addr = allocate(zone, new_size, zone->min_alignment);
+ MALLOC_ASSERT(new_addr);
+ } else {
+ new_addr = (vm_address_t)DELEGATE(malloc, new_size);
+ if (!new_addr) {
+ return (vm_address_t)NULL;
+ }
+ }
+ memcpy((void *)new_addr, (void *)addr, MIN(size, new_size));
+
+ if (guarded) {
+ deallocate(zone, addr);
+ } else {
+ DELEGATE(free, (void *)addr);
+ }
+ return new_addr;
+}
+
+
+#pragma mark -
+#pragma mark Lock Helpers
+
+static void init_lock(pgm_zone_t *zone) { _malloc_lock_init(&zone->lock); }
+static void lock(pgm_zone_t *zone) { _malloc_lock_lock(&zone->lock); }
+static void unlock(pgm_zone_t *zone) { _malloc_lock_unlock(&zone->lock); }
+static boolean_t trylock(pgm_zone_t *zone) { return _malloc_lock_trylock(&zone->lock); }
+
+
+#pragma mark -
+#pragma mark Zone Functions
+
+#define DELEGATE_UNSAMPLED(size, function, args...) \
+ if (os_likely(!should_sample(zone, size))) \
+ return DELEGATE(function, args)
+
+#define DELEGATE_UNGUARDED(ptr, function, args...) \
+ if (os_likely(!is_guarded(zone, (vm_address_t)ptr))) \
+ return DELEGATE(function, args)
+
+#define SAMPLED_ALLOCATE(size, alignment, function, args...) \
+ DELEGATE_UNSAMPLED(size, function, args); \
+ lock(zone); \
+ void *ptr = (void *)allocate(zone, size, alignment); \
+ unlock(zone); \
+ if (!ptr) return DELEGATE(function, args)
+
+#define GUARDED_DEALLOCATE(ptr, function, args...) \
+ DELEGATE_UNGUARDED(ptr, function, args); \
+ lock(zone); \
+ deallocate(zone, (vm_address_t)ptr); \
+ unlock(zone)
+
+
+static size_t
+pgm_size(pgm_zone_t *zone, const void *ptr)
+{
+ DELEGATE_UNGUARDED(ptr, size, ptr);
+ lock(zone);
+ size_t size = lookup_size(zone, (vm_address_t)ptr);
+ unlock(zone);
+ return size;
+}
+
+static void *
+pgm_malloc(pgm_zone_t *zone, size_t size)
+{
+ SAMPLED_ALLOCATE(size, zone->min_alignment, malloc, size);
+ return ptr;
+}
+
+static void *
+pgm_calloc(pgm_zone_t *zone, size_t num_items, size_t size)
+{
+ size_t total_size;
+ if (os_unlikely(os_mul_overflow(num_items, size, &total_size))) {
+ return DELEGATE(calloc, num_items, size);
+ }
+ SAMPLED_ALLOCATE(total_size, zone->min_alignment, calloc, num_items, size);
+ memset(ptr, 0, total_size);
+ return ptr;
+}
+
+static void *
+pgm_valloc(pgm_zone_t *zone, size_t size)
+{
+ SAMPLED_ALLOCATE(size, /*alignment=*/PAGE_SIZE, valloc, size);
+ return ptr;
+}
+
+static void
+pgm_free(pgm_zone_t *zone, void *ptr)
+{
+ GUARDED_DEALLOCATE(ptr, free, ptr);
+}
+
+static void *
+pgm_realloc(pgm_zone_t *zone, void *ptr, size_t new_size)
+{
+ if (os_unlikely(!ptr)) {
+ return pgm_malloc(zone, new_size);
+ }
+ boolean_t sample = should_sample(zone, new_size);
+ if (os_likely(!sample)) {
+ DELEGATE_UNGUARDED(ptr, realloc, ptr, new_size);
+ }
+ lock(zone);
+ void *new_ptr = (void *)reallocate(zone, (vm_address_t)ptr, new_size, sample);
+ unlock(zone);
+ return new_ptr;
+}
+
+static void my_vm_deallocate(vm_address_t addr, size_t size);
+static void
+pgm_destroy(pgm_zone_t *zone)
+{
+ malloc_destroy_zone(zone->wrapped_zone); // frees slots and metadata
+ my_vm_deallocate(zone->region_begin, zone->region_size);
+ my_vm_deallocate((vm_address_t)zone, sizeof(pgm_zone_t));
+}
+
+static unsigned
+pgm_batch_malloc(pgm_zone_t *zone, size_t size, void **results, unsigned count)
+{
+ if (os_unlikely(count == 0)) {
+ return 0;
+ }
+ DELEGATE_UNSAMPLED(size, batch_malloc, size, results, count);
+
+ uint32_t sample_count = 1; // Sample at least one allocation.
+ for (uint32_t i = 1; i < count; i++) {
+ if (should_sample_counter(zone->sample_counter_range)) {
+ sample_count++;
+ }
+ }
+ // TODO(yln): Express the above with only one call to rand_uniform(). "n choose k"?
+
+ for (uint32_t i = 0; i < sample_count; i++) {
+ lock(zone);
+ void *ptr = (void *)allocate(zone, size, zone->min_alignment);
+ unlock(zone);
+ if (!ptr) {
+ sample_count = i;
+ break; // Zone full.
+ }
+ results[i] = ptr;
+ }
+
+ void **remaining_results = results + sample_count;
+ uint32_t remaining_count = count - sample_count;
+ remaining_count = DELEGATE(batch_malloc, size, remaining_results, remaining_count) ;
+
+ // TODO(yln): sampled allocations will always be in the beginning of the results
+ // array. We could shuffle it: https://en.wikipedia.org/wiki/Fisher–Yates_shuffle
+ return sample_count + remaining_count;
+}
+
+static void
+pgm_batch_free(pgm_zone_t *zone, void **to_be_freed, unsigned count)
+{
+ for (uint32_t i = 0; i < count; i++) {
+ vm_address_t addr = (vm_address_t)to_be_freed[i];
+ if (os_unlikely(is_guarded(zone, addr))) {
+ lock(zone);
+ deallocate(zone, addr);
+ unlock(zone);
+ to_be_freed[i] = NULL;
+ }
+ }
+ return DELEGATE(batch_free, to_be_freed, count);
+}
+
+static void *
+pgm_memalign(pgm_zone_t *zone, size_t alignment, size_t size)
+{
+ // Delegate for (alignment > page size) and invalid alignment sizes.
+ if (alignment > PAGE_SIZE || !is_power_of_2(alignment) || alignment < sizeof(void *)) {
+ return DELEGATE(memalign, alignment, size);
+ }
+ size_t adj_alignment = MAX(alignment, zone->min_alignment);
+ SAMPLED_ALLOCATE(size, adj_alignment, memalign, alignment, size);
+ return ptr;
+}
+
+static void
+pgm_free_definite_size(pgm_zone_t *zone, void *ptr, size_t size)
+{
+ GUARDED_DEALLOCATE(ptr, free_definite_size, ptr, size);
+}
+
+static boolean_t
+pgm_claimed_address(pgm_zone_t *zone, void *ptr)
+{
+ return is_guarded(zone, (vm_address_t)ptr);
+}
+
+
+#pragma mark -
+#pragma mark Integrity Checks
+
+static const size_t k_zone_spacer = 32 * 1024 * 1024; // 32 MB
+
+static bool
+check_configuration(const pgm_zone_t *zone)
+{
+ // 0 < max_allocations << max_metadata <= num_slots <= k_max_slots
+ return (0 < zone->max_allocations) &&
+ (zone->max_allocations <= zone->max_metadata / 2) && // choose_metadata() relies on max_allocations << max_metadata
+ (zone->max_metadata <= zone->num_slots) &&
+ (zone->num_slots <= k_max_slots) &&
+ (zone->sample_counter_range > 0) &&
+ (zone->min_alignment == 1 || zone->min_alignment == 16); // strict alignment || Darwin ABI alignment
+}
+
+static bool
+check_zone(const pgm_zone_t *zone)
+{
+ return check_configuration(zone) &&
+ // Quarantine
+ (zone->size == quarantine_size(zone->num_slots)) &&
+ (zone->begin + zone->size == zone->end) &&
+ (zone->begin < zone->end) &&
+ (zone->region_size == 2 * k_zone_spacer + zone->size) &&
+ (zone->region_begin == zone->begin - k_zone_spacer) &&
+ (zone->region_begin < zone->begin) &&
+ // Mutable state
+ (zone->num_allocations <= zone->max_allocations) &&
+ (zone->num_metadata <= zone->max_metadata) &&
+ (zone->num_allocations <= zone->num_metadata) &&
+ (zone->rr_slot_index < zone->num_slots) &&
+ // Metadata
+ (zone->slots && zone->metadata) &&
+ // Statistics
+ (zone->size_in_use <= zone->max_size_in_use);
+}
+
+static bool
+check_slot(const pgm_zone_t *zone, const slot_t *slot)
+{
+ if (slot->state == ss_unused) {
+ return true;
+ }
+ return (slot->state <= ss_freed) &&
+ (slot->metadata < zone->num_metadata) &&
+ (slot->size <= PAGE_SIZE) &&
+ (slot->size == block_size(slot->size, zone->min_alignment)) &&
+ (slot->offset <= PAGE_SIZE) &&
+ (slot->offset % zone->min_alignment == 0) &&
+ ((size_t)slot->offset + slot->size <= PAGE_SIZE);
+}
+
+static bool
+check_slots(const pgm_zone_t *zone)
+{
+ uint32_t num_allocations = 0;
+ size_t size_in_use = 0;
+
+ for (uint32_t i = 0; i < zone->num_slots; i++) {
+ slot_t *slot = &zone->slots[i];
+ if (!check_slot(zone, slot)) {
+ return false;
+ }
+ if (slot->state == ss_allocated) {
+ num_allocations++;
+ size_in_use += zone->slots[i].size;
+ }
+ }
+
+ return (num_allocations == zone->num_allocations) &&
+ (size_in_use == zone->size_in_use);
+}
+
+static bool
+check_md(const pgm_zone_t *zone, const metadata_t *md)
+{
+ ptrdiff_t index = md - zone->metadata;
+ return (md->slot < zone->num_slots) &&
+ (zone->slots[md->slot].metadata == index) &&
+ ((size_t)md->alloc.trace_size + md->dealloc.trace_size <= sizeof(md->trace_buffer));
+}
+
+static bool
+check_metadata(const pgm_zone_t *zone)
+{
+ for (uint32_t i = 0; i < zone->num_metadata; i++) {
+ metadata_t *metadata = &zone->metadata[i];
+ if (!check_md(zone, metadata)) {
+ return false;
+ }
+ }
+ return true;
+}
+
+
+#pragma mark -
+#pragma mark Introspection Functions
+
+typedef enum { rt_zone_only, rt_slots, rt_slots_and_metadata } read_type_t;
+
+#define READ(remote_address, size, local_memory, checker, zone) \
+{ \
+ kern_return_t kr = reader(task, (vm_address_t)remote_address, size, (void **)local_memory); \
+ if (kr != KERN_SUCCESS) return kr; \
+ if (!checker(zone)) return KERN_FAILURE; \
+}
+
+static kern_return_t
+read_zone(task_t task, vm_address_t zone_address, memory_reader_t reader, pgm_zone_t *zone, read_type_t read_type)
+{
+ if (!reader && task == mach_task_self()) {
+ reader = _malloc_default_reader;
+ }
+
+ pgm_zone_t *zone_ptr;
+ READ(zone_address, sizeof(pgm_zone_t), &zone_ptr, check_zone, zone_ptr);
+ *zone = *zone_ptr; // Copy to writable memory
+
+ if (read_type >= rt_slots) {
+ READ(zone->slots, zone->num_slots * sizeof(slot_t), &zone->slots, check_slots, zone);
+ }
+ if (read_type >= rt_slots_and_metadata) {
+ READ(zone->metadata, zone->max_metadata * sizeof(metadata_t), &zone->metadata, check_metadata, zone);
+ }
+ return KERN_SUCCESS;
+}
+
+#define READ_ZONE(zone, read_type) \
+ pgm_zone_t zone_copy; \
+ { \
+ kern_return_t kr = read_zone(task, zone_address, reader, &zone_copy, read_type); \
+ if (kr != KERN_SUCCESS) return kr; \
+ } \
+ pgm_zone_t *zone = &zone_copy;
+
+#define RECORD(remote_address, size_, type) \
+{ \
+ vm_range_t range = { .address = remote_address, .size = size_ }; \
+ recorder(task, context, type, &range, /*count=*/1); \
+}
+
+static kern_return_t
+pgm_enumerator(task_t task, void *context, unsigned type_mask,
+ vm_address_t zone_address, memory_reader_t reader,
+ vm_range_recorder_t recorder)
+{
+ boolean_t record_allocs = (type_mask & MALLOC_PTR_IN_USE_RANGE_TYPE);
+ boolean_t record_regions = (type_mask & MALLOC_PTR_REGION_RANGE_TYPE);
+ if (!record_allocs && !record_regions) {
+ return KERN_SUCCESS;
+ }
+
+ READ_ZONE(zone, rt_slots);
+
+ for (uint32_t i = 0; i < zone->num_slots; i++) {
+ if (zone->slots[i].state != ss_allocated) {
+ continue;
+ }
+ // TODO(yln): we could do these in bulk. Currently, it shouldn't matter
+ // since the number of active slots (bounded by max_allocations) is small.
+ // If we optimize our allocator (to prevent wasting a page per allocation)
+ // and this allows us to significantly grow the number of allocations, then
+ // we should change the code here to record in chunks.
+ if (record_regions) {
+ vm_address_t page = page_addr(zone, i);
+ RECORD(page, PAGE_SIZE, MALLOC_PTR_REGION_RANGE_TYPE);
+ }
+ if (record_allocs) {
+ vm_address_t alloc = block_addr(zone, i);
+ RECORD(alloc, zone->slots[i].size, MALLOC_PTR_IN_USE_RANGE_TYPE);
+ }
+ }
+ return KERN_SUCCESS;
+}
+
+static void
+pgm_statistics(pgm_zone_t *zone, malloc_statistics_t *stats)
+{
+ *stats = (malloc_statistics_t){
+ .blocks_in_use = zone->num_allocations,
+ .size_in_use = zone->size_in_use,
+ .max_size_in_use = zone->max_size_in_use,
+ .size_allocated = zone->num_allocations * PAGE_SIZE
+ };
+}
+
+static kern_return_t
+pgm_statistics_task(task_t task, vm_address_t zone_address, memory_reader_t reader, malloc_statistics_t *stats)
+{
+ READ_ZONE(zone, rt_zone_only);
+ pgm_statistics(zone, stats);
+ return KERN_SUCCESS;
+}
+
+static void
+print_zone(pgm_zone_t *zone, boolean_t verbose, print_task_printer_t printer) {
+ malloc_statistics_t stats;
+ pgm_statistics(zone, &stats);
+ printer("ProbGuard zone: slots: %u, slots in use: %u, size in use: %llu, max size in use: %llu, allocated size: %llu\n",
+ zone->num_slots, stats.blocks_in_use, stats.size_in_use, stats.max_size_in_use, stats.size_allocated);
+ printer("Quarantine: size: %llu, address range: [%p - %p)\n", zone->size, zone->begin, zone->end);
+
+ printer("Slots (#, state, offset, size, block address):\n");
+ for (uint32_t i = 0; i < zone->num_slots; i++) {
+ slot_state_t state = zone->slots[i].state;
+ if (state != ss_allocated && !verbose) {
+ continue;
+ }
+ const char *label = slot_state_labels[state];
+ uint16_t offset = zone->slots[i].offset;
+ uint16_t size = zone->slots[i].size;
+ vm_address_t block = block_addr(zone, i);
+ printer("%4u, %9s, %4u, %4u, %p\n", i, label, offset, size, block);
+ }
+}
+
+
+static void
+pgm_print(pgm_zone_t *zone, boolean_t verbose)
+{
+ print_zone(zone, verbose, malloc_report_simple);
+}
+
+static void
+pgm_print_task(task_t task, unsigned level, vm_address_t zone_address, memory_reader_t reader, print_task_printer_t printer)
+{
+ pgm_zone_t zone;
+ kern_return_t kr = read_zone(task, zone_address, reader, &zone, rt_slots);
+ if (kr != KERN_SUCCESS) {
+ printer("Failed to read ProbGuard zone at %p\n", zone_address);
+ return;
+ }
+
+ boolean_t verbose = (level >= MALLOC_VERBOSE_PRINT_LEVEL);
+ print_zone(&zone, verbose, printer);
+}
+
+static void
+pgm_log(pgm_zone_t *zone, void *address)
+{
+ // Unsupported.
+}
+
+static size_t
+pgm_good_size(pgm_zone_t *zone, size_t size)
+{
+ return DELEGATE(introspect->good_size, size);
+}
+
+static boolean_t
+pgm_check(pgm_zone_t *zone)
+{
+ return check_zone(zone) && check_slots(zone) && check_metadata(zone);
+}
+
+static void
+pgm_force_lock(pgm_zone_t *zone)
+{
+ lock(zone);
+}
+
+static void
+pgm_force_unlock(pgm_zone_t *zone)
+{
+ unlock(zone);
+}
+
+static void
+pgm_reinit_lock(pgm_zone_t *zone)
+{
+ init_lock(zone);
+}
+
+static boolean_t
+pgm_zone_locked(pgm_zone_t *zone)
+{
+ boolean_t lock_taken = trylock(zone);
+ if (lock_taken) {
+ unlock(zone);
+ }
+ return !lock_taken;
+}
+
+
+#pragma mark -
+#pragma mark Zone Templates
+
+// Suppress warning: incompatible function pointer types
+#define FN_PTR(fn) (void *)(&fn)
+
+static const malloc_introspection_t introspection_template = {
+ // Block and region enumeration
+ .enumerator = FN_PTR(pgm_enumerator),
+
+ // Statistics
+ .statistics = FN_PTR(pgm_statistics),
+ .task_statistics = FN_PTR(pgm_statistics_task),
+
+ // Logging
+ .print = FN_PTR(pgm_print),
+ .print_task = FN_PTR(pgm_print_task),
+ .log = FN_PTR(pgm_log),
+
+ // Queries
+ .good_size = FN_PTR(pgm_good_size),
+ .check = FN_PTR(pgm_check),
+
+ // Locking
+ .force_lock = FN_PTR(pgm_force_lock),
+ .force_unlock = FN_PTR(pgm_force_unlock),
+ .reinit_lock = FN_PTR(pgm_reinit_lock),
+ .zone_locked = FN_PTR(pgm_zone_locked),
+
+ // Discharge checking
+ .enable_discharge_checking = NULL,
+ .disable_discharge_checking = NULL,
+ .discharge = NULL,
+#ifdef __BLOCKS__
+ .enumerate_discharged_pointers = NULL,
+#else
+ .enumerate_unavailable_without_blocks = NULL,
+#endif
+};
+
+static const malloc_zone_t malloc_zone_template = {
+ // Reserved for CFAllocator
+ .reserved1 = NULL,
+ .reserved2 = NULL,
+
+ // Standard operations
+ .size = FN_PTR(pgm_size),
+ .malloc = FN_PTR(pgm_malloc),
+ .calloc = FN_PTR(pgm_calloc),
+ .valloc = FN_PTR(pgm_valloc),
+ .free = FN_PTR(pgm_free),
+ .realloc = FN_PTR(pgm_realloc),
+ .destroy = FN_PTR(pgm_destroy),
+
+ // Batch operations
+ .batch_malloc = FN_PTR(pgm_batch_malloc),
+ .batch_free = FN_PTR(pgm_batch_free),
+
+ // Introspection
+ .zone_name = "ProbGuardMallocZone",
+ .version = 12,
+ .introspect = (malloc_introspection_t *)&introspection_template, // Effectively const.
+
+ // Specialized operations
+ .memalign = FN_PTR(pgm_memalign),
+ .free_definite_size = FN_PTR(pgm_free_definite_size),
+ .pressure_relief = NULL,
+ .claimed_address = FN_PTR(pgm_claimed_address)
+};
+
+
+#pragma mark -
+#pragma mark Configuration Options
+
+static const char *
+env_var(const char *name)
+{
+ const char **env = (const char **)*_NSGetEnviron();
+ return _simple_getenv(env, name);
+}
+
+static uint32_t
+env_uint(const char *name, uint32_t default_value) {
+ const char *value = env_var(name);
+ if (!value) return default_value;
+ return (uint32_t)strtoul(value, NULL, 0);
+}
+
+static boolean_t
+env_bool(const char *name) {
+ const char *value = env_var(name);
+ if (!value) return FALSE;
+ return value[0] == '1';
+}
+
+#if CONFIG_FEATUREFLAGS_SIMPLE
+# define FEATURE_FLAG(feature, default) os_feature_enabled_simple(libmalloc, feature, default)
+#else
+# define FEATURE_FLAG(feature, default) (default)
+#endif
+
+
+#pragma mark -
+#pragma mark Zone Configuration
+
+static bool
+is_platform_binary(void)
+{
+ uint32_t flags = 0;
+ int err = csops(getpid(), CS_OPS_STATUS, &flags, sizeof(flags));
+ if (err) {
+ return false;
+ }
+ return (flags & CS_PLATFORM_BINARY);
+}
+
+extern bool main_image_has_section(const char* segname, const char *sectname);
+static bool
+should_activate(bool internal_build)
+{
+ if (!internal_build && !is_platform_binary()) {
+ return false;
+ }
+#if TARGET_OS_OSX
+ uint32_t activation_rate = (internal_build ? 250 : 1000);
+ if (rand_uniform(activation_rate) != 0) {
+ return false;
+ }
+#else
+ if (!env_bool("MallocProbGuardViaLaunchd")) {
+ return false;
+ }
+#endif
+ if (main_image_has_section("__DATA", "__pgm_opt_out")) {
+ return false;
+ }
+ return true;
+}
+
+#if TARGET_OS_WATCH || TARGET_OS_TV
+static bool
+is_high_memory_device(void)
+{
+ uint64_t high_memory = 1.2 * 1024 * 1024 * 1024; // 1.2 GB
+ return platform_hw_memsize() > high_memory;
+}
+#endif
+
+bool
+pgm_should_enable(bool internal_build)
+{
+ if (env_var("MallocProbGuard")) {
+ return env_bool("MallocProbGuard");
+ }
+ if (FEATURE_FLAG(ProbGuard, true) && should_activate(internal_build)) {
+#if TARGET_OS_OSX || TARGET_OS_IOS
+ return true;
+#elif TARGET_OS_WATCH || TARGET_OS_TV
+ if (is_high_memory_device()) {
+ return true;
+ }
+#elif TARGET_OS_DRIVERKIT
+ // Never enable for DriverKit
+#else
+ if (internal_build) {
+ return true;
+ }
+#endif
+ }
+ if (FEATURE_FLAG(ProbGuardAllProcesses, false)) {
+ return true;
+ }
+ return false;
+}
+
+static uint32_t
+choose_memory_budget_in_kb(void)
+{
+ return (TARGET_OS_OSX ? 8 : 2) * 1024;
+}
+
+static uint32_t
+choose_sample_rate(void)
+{
+ uint32_t min = 500, max = 5000;
+ return rand_uniform(max - min) + min;
+}
+
+static const double k_slot_multiplier = 10.0;
+static const double k_metadata_multiplier = 3.0;
+static uint32_t
+compute_max_allocations(size_t memory_budget_in_kb)
+{
+ size_t memory_budget = memory_budget_in_kb * 1024;
+ size_t fixed_overhead = round_page(sizeof(pgm_zone_t));
+ size_t vm_map_entry_size = 80; // struct vm_map_entry in <vm/vm_map.h>
+ size_t per_allocation_overhead =
+ PAGE_SIZE +
+ k_slot_multiplier * 2 * vm_map_entry_size + // TODO(yln): Implement mark_inaccessible to fill holes so we can drop the k_slot_multiplier here. +27% more protected allocations!
+ // 2 * vm_map_entry_size + // Allocations split the VM region
+ k_slot_multiplier * sizeof(slot_t) +
+ k_metadata_multiplier * sizeof(metadata_t);
+
+ uint32_t max_allocations = (uint32_t)((memory_budget - fixed_overhead) / per_allocation_overhead);
+ if (memory_budget < fixed_overhead || max_allocations == 0) {
+ MALLOC_REPORT_FATAL_ERROR(0, "ProbGuard: memory budget too small");
+ }
+ return max_allocations;
+}
+
+static void
+configure_zone(pgm_zone_t *zone)
+{
+ uint32_t memory_budget_in_kb = env_uint("MallocProbGuardMemoryBudgetInKB", choose_memory_budget_in_kb());
+ zone->max_allocations = env_uint("MallocProbGuardAllocations", compute_max_allocations(memory_budget_in_kb));
+ zone->num_slots = env_uint("MallocProbGuardSlots", k_slot_multiplier * zone->max_allocations);
+ zone->max_metadata = env_uint("MallocProbGuardMetadata", k_metadata_multiplier * zone->max_allocations);
+ uint32_t sample_rate = env_uint("MallocProbGuardSampleRate", choose_sample_rate());
+ // Approximate a (1 / sample_rate) chance for sampling; 1 means "always sample".
+ zone->sample_counter_range = (sample_rate != 1) ? (2 * sample_rate) : 1;
+ bool strict_alignment = env_var("MallocProbGuardStrictAlignment") ? env_bool("MallocProbGuardStrictAlignment") : FEATURE_FLAG(ProbGuardStrictAlignment, false);
+ zone->min_alignment = (strict_alignment && MALLOC_TARGET_64BIT) ? 1 : 16; // Darwin ABI requires 16 byte alignment.
+ zone->signal_handler = env_bool("MallocProbGuardSignalHandler");
+ zone->debug = env_bool("MallocProbGuardDebug");
+ zone->debug_log_throttle_ms = env_uint("MallocProbGuardDebugLogThrottleInMillis", 1000);
+
+ if (zone->debug) {
+ malloc_report(ASL_LEVEL_INFO,
+ "ProbGuard configuration: %u kB budget, 1/%u sample rate, %u/%u/%u allocations/metadata/slots, strict alignment: %d\n",
+ memory_budget_in_kb, sample_rate, zone->max_allocations, zone->max_metadata, zone->num_slots, strict_alignment);
+ }
+ if (!check_configuration(zone)) {
+ MALLOC_REPORT_FATAL_ERROR(0, "ProbGuard: bad configuration");
+ }
+}
+
+
+#pragma mark -
+#pragma mark Zone Creation
+
+#define VM_PROT_READ_WRITE (VM_PROT_READ | VM_PROT_WRITE)
+
+static vm_address_t my_vm_map(size_t size, vm_prot_t protection, int tag);
+static void my_vm_map_fixed(vm_address_t addr, size_t size, vm_prot_t protection, int tag);
+static void my_vm_deallocate(vm_address_t addr, size_t size);
+static void my_vm_protect(vm_address_t addr, size_t size, vm_prot_t protection);
+
+static void
+setup_zone(pgm_zone_t *zone, malloc_zone_t *wrapped_zone)
+{
+ // Malloc zone
+ zone->malloc_zone = malloc_zone_template;
+ zone->wrapped_zone = wrapped_zone;
+
+ // Configuration
+ configure_zone(zone);
+
+ // Quarantine
+ zone->size = quarantine_size(zone->num_slots);
+ zone->region_size = 2 * k_zone_spacer + zone->size;
+ zone->region_begin = my_vm_map(zone->region_size, VM_PROT_NONE, VM_MEMORY_MALLOC);
+ zone->begin = zone->region_begin + k_zone_spacer;
+ zone->end = zone->begin + zone->size;
+ my_vm_map_fixed(zone->begin, zone->size, VM_PROT_NONE, VM_MEMORY_MALLOC_PROB_GUARD);
+
+ // Metadata
+ zone->slots = DELEGATE(calloc, zone->num_slots, sizeof(slot_t));
+ zone->metadata = DELEGATE(calloc, zone->max_metadata, sizeof(metadata_t));
+ MALLOC_ASSERT(zone->slots && zone->metadata);
+
+ // Mutable state
+ init_lock(zone);
+}
+
+static void install_signal_handler(void *unused);
+malloc_zone_t *
+pgm_create_zone(malloc_zone_t *wrapped_zone)
+{
+ // rdar://74948496 ([PGM] Drop all requirements for wrapped_zone)
+ MALLOC_ASSERT(wrapped_zone->version >= 6);
+ MALLOC_ASSERT(wrapped_zone->batch_malloc && wrapped_zone->batch_free &&
+ wrapped_zone->memalign && wrapped_zone->free_definite_size);
+
+ pgm_zone_t *zone = (pgm_zone_t *)my_vm_map(sizeof(pgm_zone_t), VM_PROT_READ_WRITE, VM_MEMORY_MALLOC);
+ setup_zone(zone, wrapped_zone);
+ my_vm_protect((vm_address_t)zone, PAGE_MAX_SIZE, VM_PROT_READ);
+
+ if (zone->signal_handler) {
+ static os_once_t once_pred;
+ os_once(&once_pred, NULL, &install_signal_handler);
+ }
+
+ return (malloc_zone_t *)zone;
+}
+
+
+#pragma mark -
+#pragma mark Logging
+
+static uint64_t
+to_millis(uint64_t mach_ticks)
+{
+ mach_timebase_info_data_t timebase;
+ mach_timebase_info(&timebase);
+ const uint64_t nanos_per_ms = 1e6;
+ return (mach_ticks * timebase.numer / timebase.denom) / nanos_per_ms;
+}
+
+static bool
+should_log(pgm_zone_t *zone)
+{
+ uint64_t now = mach_absolute_time();
+ uint64_t delta_ms = to_millis(now - zone->last_log_time);
+ boolean_t log = (delta_ms >= zone->debug_log_throttle_ms);
+ if (log) {
+ zone->last_log_time = now;
+ }
+ return log;
+}
+
+static void
+debug_zone(pgm_zone_t *zone, const char *label, vm_address_t addr)
+{
+ if (!zone->debug) {
+ return;
+ }
+ if (should_log(zone)) {
+ malloc_report(ASL_LEVEL_INFO, "ProbGuard: %9s 0x%lx, fill state: %3u/%u\n",
+ label, addr, zone->num_allocations, zone->max_allocations);
+ }
+ if (!pgm_check(zone)) {
+ MALLOC_REPORT_FATAL_ERROR(addr, "ProbGuard: zone integrity check failed");
+ }
+}
+
+
+#pragma mark -
+#pragma mark Fault Diagnosis
+
+static void
+fill_in_trace(const alloc_info_t *info, const uint8_t *buffer, stack_trace_t *trace)
+{
+ trace->thread_id = info->thread_id;
+ trace->time = info->time;
+ uint32_t max_frames = sizeof(trace->frames) / sizeof(trace->frames[0]);
+ trace->num_frames = trace_decode(buffer, info->trace_size, trace->frames, max_frames);
+}
+
+static void
+fill_in_report(const pgm_zone_t *zone, uint32_t slot, pgm_report_t *report)
+{
+ slot_t *s = &zone->slots[slot];
+ metadata_t *m = &zone->metadata[s->metadata];
+
+ report->nearest_allocation = block_addr(zone, slot);
+ report->allocation_size = s->size;
+ report->allocation_state = slot_state_labels[s->state];
+ report->num_traces = 0;
+
+ if (m->slot == slot) {
+ report->num_traces++;
+ fill_in_trace(&m->alloc, m->trace_buffer, &report->alloc_trace);
+ if (s->state == ss_freed) {
+ report->num_traces++;
+ uint8_t *buffer = &m->trace_buffer[m->alloc.trace_size];
+ fill_in_trace(&m->dealloc, buffer, &report->dealloc_trace);
+ }
+ }
+}
+
+static void
+diagnose_page_fault(const pgm_zone_t *zone, vm_address_t fault_address, pgm_report_t *report)
+{
+ slot_lookup_t res = lookup_slot(zone, fault_address);
+ MALLOC_ASSERT(res.slot < zone->num_slots);
+ MALLOC_ASSERT(zone->slots[res.slot].metadata < zone->max_metadata);
+ slot_state_t ss = zone->slots[res.slot].state;
+
+ // We got here because of a page fault.
+ MALLOC_ASSERT(ss != ss_allocated || res.bounds == b_oob_guard_page);
+
+ // Note that all of the following error conditions may also be caused by:
+ // *) Randomly corrupted pointer
+ // *) Long-range OOB (access stride > (page size / 2))
+ // We will always misdiagnose some of these errors no matter how we slice it.
+
+ // TODO(yln): extract "nearest allocation helper"
+ switch (ss) {
+ case ss_unused:
+ // Nearest slot was never used.
+ // TODO(yln): if bounds == oob_guard_page; we could try to look at the slot on the other side of the guard page.
+ report->error_type = "long-range OOB";
+ report->confidence = "low";
+ break;
+ case ss_allocated:
+ // Most likely an OOB access from an active allocation onto a guard page.
+ MALLOC_ASSERT(res.bounds == b_oob_guard_page);
+ report->error_type = "out-of-bounds";
+ report->confidence = "high";
+ break;
+ case ss_freed:
+ if (res.bounds == b_block_addr || res.bounds == b_valid) {
+ report->error_type = "use-after-free";
+ report->confidence = "high";
+ } else {
+ MALLOC_ASSERT(res.bounds == b_oob_slot || res.bounds == b_oob_guard_page);
+ // This could be a combination of OOB and UAF, or one of the generic errors
+ // outlined above.
+ // TODO(yln): still try to diagnose something here
+ report->error_type = "OOB + UAF";
+ report->confidence = "low";
+ }
+ break;
+ default:
+ __builtin_unreachable();
+ }
+
+ report->fault_address = fault_address;
+ fill_in_report(zone, res.slot, report);
+}
+
+
+#pragma mark -
+#pragma mark Error Printing
+
+static const uint32_t k_buf_len = 1024;
+static void
+get_symbol_and_module_name(vm_address_t addr, char buf[k_buf_len])
+{
+ int success = 0;
+#if !TARGET_OS_DRIVERKIT
+ Dl_info info;
+ success = dladdr((void *)addr, &info);
+ if (success) {
+ snprintf(buf, k_buf_len, "%s (%s)", info.dli_sname, info.dli_fname);
+ }
+#endif
+ if (!success) {
+ snprintf(buf, k_buf_len, "%p", (void *)addr);
+ }
+}
+
+static void
+print_trace(stack_trace_t *trace, const char *label)
+{
+ malloc_report(ASL_LEVEL_ERR, "%s trace (thread %llu, time: %llu):\n", label, trace->thread_id, trace->time);
+ for (uint32_t i = 0; i < trace->num_frames; i++) {
+ char sym_name[k_buf_len];
+ get_symbol_and_module_name(trace->frames[i], sym_name);
+ malloc_report(ASL_LEVEL_ERR, " #%u %s\n", i, sym_name);
+ }
+ malloc_report(ASL_LEVEL_ERR, "\n", label);
+}
+
+static void
+print_report(pgm_report_t *report)
+{
+ malloc_report(ASL_LEVEL_ERR, "ProbGuard: invalid access at 0x%lx\n",
+ report->fault_address);
+ malloc_report(ASL_LEVEL_ERR, "Error type: %s (%s confidence)\n",
+ report->error_type, report->confidence);
+ malloc_report(ASL_LEVEL_ERR, "Nearest allocation: 0x%lx, size: %lu, state: %s\n",
+ report->nearest_allocation, report->allocation_size, report->allocation_state);
+
+ if (report->num_traces >= 1) {
+ print_trace(&report->alloc_trace, "Allocation");
+ if (report->num_traces >= 2) {
+ print_trace(&report->dealloc_trace, "Deallocation");
+ }
+ } else {
+ malloc_report(ASL_LEVEL_ERR, "Allocation stack traces not available. "
+ "Try increasing `MallocProbGuardMetadata` and rerun.\n");
+ }
+}
+
+
+#pragma mark -
+#pragma mark Crash Reporter API
+
+static kern_return_t
+diagnose_fault_from_external_process(vm_address_t fault_address, pgm_report_t *report,
+ task_t task, vm_address_t zone_address, memory_reader_t reader)
+{
+ READ_ZONE(zone, rt_slots_and_metadata);
+ diagnose_page_fault(zone, fault_address, report);
+ return KERN_SUCCESS;
+}
+
+static crash_reporter_memory_reader_t g_crm_reader;
+static const uint32_t k_max_read_memory = 3;
+static void *read_memory[k_max_read_memory];
+static uint32_t num_read_memory;
+static kern_return_t
+memory_reader_adapter(task_t task, vm_address_t address, vm_size_t size, void **local_memory)
+{
+ MALLOC_ASSERT(num_read_memory < k_max_read_memory);
+ void *ptr = g_crm_reader(task, address, size);
+ *local_memory = ptr;
+ read_memory[num_read_memory++] = ptr;
+ return ptr ? KERN_SUCCESS : KERN_FAILURE;
+}
+
+static memory_reader_t *
+setup_memory_reader(crash_reporter_memory_reader_t crm_reader)
+{
+ g_crm_reader = crm_reader;
+ num_read_memory = 0;
+ return memory_reader_adapter;
+}
+
+static void
+free_read_memory()
+{
+ for (uint32_t i = 0; i < num_read_memory; i++) {
+ free(read_memory[i]);
+ }
+}
+
+static _malloc_lock_s crash_reporter_lock = _MALLOC_LOCK_INIT;
+kern_return_t
+pgm_diagnose_fault_from_crash_reporter(vm_address_t fault_address, pgm_report_t *report,
+ task_t task, vm_address_t zone_address, crash_reporter_memory_reader_t crm_reader)
+{
+ _malloc_lock_lock(&crash_reporter_lock);
+
+ memory_reader_t *reader = setup_memory_reader(crm_reader);
+ kern_return_t kr = diagnose_fault_from_external_process(fault_address, report, task, zone_address, reader);
+ free_read_memory();
+
+ _malloc_lock_unlock(&crash_reporter_lock);
+ return kr;
+}
+
+
+#pragma mark -
+#pragma mark Signal Handler
+
+extern malloc_zone_t **malloc_zones;
+static void
+report_error_from_signal_handler(vm_address_t fault_address)
+{
+ pgm_zone_t *zone = (pgm_zone_t *)malloc_zones[0];
+ MALLOC_ASSERT(zone->malloc_zone.size == FN_PTR(pgm_size));
+
+ if (!is_guarded(zone, fault_address)) {
+ return;
+ }
+
+ pgm_report_t report;
+ {
+ trylock(zone); // Best-effort locking to avoid deadlock.
+ diagnose_page_fault(zone, fault_address, &report);
+ unlock(zone);
+ }
+ print_report(&report);
+
+ MALLOC_REPORT_FATAL_ERROR(fault_address, "ProbGuard: invalid access detected");
+}
+
+static struct sigaction prev_sigaction;
+static void
+signal_handler(int sig, siginfo_t *info, void *ucontext)
+{
+ MALLOC_ASSERT(sig == SIGBUS);
+ report_error_from_signal_handler((vm_address_t)info->si_addr);
+
+ // Delegate to previous handler.
+ if (prev_sigaction.sa_flags & SA_SIGINFO) {
+ prev_sigaction.sa_sigaction(sig, info, ucontext);
+ } else if (prev_sigaction.sa_handler == SIG_IGN ||
+ prev_sigaction.sa_handler == SIG_DFL) {
+ // If the previous handler was the default handler, or was ignoring this
+ // signal, install the default handler and re-raise the signal in order to
+ // get a core dump and terminate this process.
+ signal(SIGBUS, SIG_DFL);
+ raise(SIGBUS);
+ } else {
+ prev_sigaction.sa_handler(sig);
+ }
+}
+
+static void
+install_signal_handler(void *unused)
+{
+ struct sigaction act = {
+ .sa_sigaction = &signal_handler,
+ .sa_flags = SA_SIGINFO
+ };
+ int res = sigaction(SIGBUS, &act, &prev_sigaction);
+ MALLOC_ASSERT(res == 0);
+}
+
+
+#pragma mark -
+#pragma mark Mockable Helpers
+
+#ifndef PGM_MOCK_RANDOM
+static uint32_t
+rand_uniform(uint32_t upper_bound)
+{
+ MALLOC_ASSERT(upper_bound > 0);
+ return arc4random_uniform(upper_bound);
+}
+#endif
+
+#ifndef PGM_MOCK_TRACE_COLLECT
+MALLOC_ALWAYS_INLINE
+static inline size_t
+my_trace_collect(uint8_t *buffer, size_t size)
+{
+ return trace_collect(buffer, size);
+}
+#endif
+
+#ifndef PGM_MOCK_PAGE_ACCESS
+static void
+mark_inaccessible(vm_address_t page)
+{
+ int res = madvise((void *)page, PAGE_SIZE, CONFIG_MADVISE_STYLE);
+ MALLOC_ASSERT(res == 0);
+ my_vm_protect(page, PAGE_SIZE, VM_PROT_NONE);
+}
+
+static void
+mark_read_write(vm_address_t page)
+{
+ // It is faster to just unprotect the page without calling madvise() first.
+ my_vm_protect(page, PAGE_SIZE, VM_PROT_READ_WRITE);
+}
+#endif
+
+
+#pragma mark -
+#pragma mark Mach VM Helpers
+
+static vm_address_t
+my_vm_map_common(vm_address_t addr, size_t size, vm_prot_t protection, int vm_flags, int tag)
+{
+ vm_map_t target = mach_task_self();
+ mach_vm_address_t address = addr;
+ mach_vm_size_t size_rounded = round_page(size);
+ mach_vm_offset_t mask = 0x0;
+ int flags = vm_flags | VM_MAKE_TAG(tag);
+ mem_entry_name_port_t object = MEMORY_OBJECT_NULL;
+ memory_object_offset_t offset = 0;
+ boolean_t copy = FALSE;
+ vm_prot_t cur_protection = protection;
+ vm_prot_t max_protection = VM_PROT_READ | VM_PROT_WRITE;
+ vm_inherit_t inheritance = VM_INHERIT_DEFAULT;
+
+ kern_return_t kr = mach_vm_map(target, &address, size_rounded, mask, flags,
+ object, offset, copy, cur_protection, max_protection, inheritance);
+ MALLOC_ASSERT(kr == KERN_SUCCESS);
+ return address;
+}
+
+static vm_address_t
+my_vm_map(size_t size, vm_prot_t protection, int tag)
+{
+ return my_vm_map_common(0, size, protection, VM_FLAGS_ANYWHERE, tag);
+}
+
+static void
+my_vm_map_fixed(vm_address_t addr, size_t size, vm_prot_t protection, int tag)
+{
+ int flags = VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE;
+ vm_address_t addr2 = my_vm_map_common(addr, size, protection, flags, tag);
+ MALLOC_ASSERT(addr2 == addr);
+}
+
+static void
+my_vm_deallocate(vm_address_t addr, size_t size)
+{
+ vm_map_t target = mach_task_self();
+ mach_vm_address_t address = (mach_vm_address_t)addr;
+ mach_vm_size_t size_rounded = round_page(size);
+ kern_return_t kr = mach_vm_deallocate(target, address, size_rounded);
+ MALLOC_ASSERT(kr == KERN_SUCCESS);
+}
+
+static void
+my_vm_protect(vm_address_t addr, size_t size, vm_prot_t protection) {
+ vm_map_t target = mach_task_self();
+ mach_vm_address_t address = (mach_vm_address_t)addr;
+ mach_vm_size_t size_rounded = round_page(size);
+ boolean_t set_maximum = FALSE;
+ kern_return_t kr = mach_vm_protect(target, address, size_rounded, set_maximum, protection);
+ MALLOC_ASSERT(kr == KERN_SUCCESS);
+}