8cbd12b9b7
Avoids situation where data has been overwritten during any post-mortem analysis (core dump, gdbstub, etc). As reported via forum https://esp32.com/viewtopic.php?f=2&t=6471&p=27790
383 lines
12 KiB
C
383 lines
12 KiB
C
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <stdint.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <assert.h>
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#include <string.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <sys/param.h>
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#include <multi_heap.h>
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#include "multi_heap_internal.h"
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/* Note: Keep platform-specific parts in this header, this source
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file should depend on libc only */
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#include "multi_heap_platform.h"
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/* Defines compile-time configuration macros */
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#include "multi_heap_config.h"
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#ifdef MULTI_HEAP_POISONING
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/* Alias MULTI_HEAP_POISONING_SLOW to SLOW for better readabilty */
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#ifdef SLOW
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#error "external header has defined SLOW"
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#endif
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#ifdef MULTI_HEAP_POISONING_SLOW
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#define SLOW 1
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#endif
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#define MALLOC_FILL_PATTERN 0xce
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#define FREE_FILL_PATTERN 0xfe
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#define HEAD_CANARY_PATTERN 0xABBA1234
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#define TAIL_CANARY_PATTERN 0xBAAD5678
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typedef struct {
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uint32_t head_canary;
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MULTI_HEAP_BLOCK_OWNER
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size_t alloc_size;
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} poison_head_t;
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typedef struct {
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uint32_t tail_canary;
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} poison_tail_t;
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#define POISON_OVERHEAD (sizeof(poison_head_t) + sizeof(poison_tail_t))
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/* Given a "poisoned" region with pre-data header 'head', and actual data size 'alloc_size', fill in the head and tail
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region checks.
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Returns the pointer to the actual usable data buffer (ie after 'head')
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*/
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static uint8_t *poison_allocated_region(poison_head_t *head, size_t alloc_size)
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{
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uint8_t *data = (uint8_t *)(&head[1]); /* start of data ie 'real' allocated buffer */
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poison_tail_t *tail = (poison_tail_t *)(data + alloc_size);
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head->alloc_size = alloc_size;
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head->head_canary = HEAD_CANARY_PATTERN;
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MULTI_HEAP_SET_BLOCK_OWNER(head);
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uint32_t tail_canary = TAIL_CANARY_PATTERN;
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if ((intptr_t)tail % sizeof(void *) == 0) {
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tail->tail_canary = tail_canary;
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} else {
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/* unaligned tail_canary */
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memcpy(&tail->tail_canary, &tail_canary, sizeof(uint32_t));
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}
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return data;
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}
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/* Given a pointer to some allocated data, check the head & tail poison structures (before & after it) that were
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previously injected by poison_allocated_region().
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Returns a pointer to the poison header structure, or NULL if the poison structures are corrupt.
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*/
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static poison_head_t *verify_allocated_region(void *data, bool print_errors)
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{
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poison_head_t *head = (poison_head_t *)((intptr_t)data - sizeof(poison_head_t));
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poison_tail_t *tail = (poison_tail_t *)((intptr_t)data + head->alloc_size);
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/* check if the beginning of the data was overwritten */
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if (head->head_canary != HEAD_CANARY_PATTERN) {
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if (print_errors) {
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MULTI_HEAP_STDERR_PRINTF("CORRUPT HEAP: Bad head at %p. Expected 0x%08x got 0x%08x\n", &head->head_canary,
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HEAD_CANARY_PATTERN, head->head_canary);
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}
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return NULL;
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}
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/* check if the end of the data was overrun */
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uint32_t canary;
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if ((intptr_t)tail % sizeof(void *) == 0) {
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canary = tail->tail_canary;
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} else {
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/* tail is unaligned */
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memcpy(&canary, &tail->tail_canary, sizeof(canary));
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}
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if (canary != TAIL_CANARY_PATTERN) {
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if (print_errors) {
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printf("CORRUPT HEAP: Bad tail at %p. Expected 0x%08x got 0x%08x\n", &tail->tail_canary,
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TAIL_CANARY_PATTERN, canary);
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}
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return NULL;
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}
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return head;
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}
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#ifdef SLOW
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/* Go through a region that should have the specified fill byte 'pattern',
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verify it.
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if expect_free is true, expect FREE_FILL_PATTERN otherwise MALLOC_FILL_PATTERN.
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if swap_pattern is true, swap patterns in the buffer (ie replace MALLOC_FILL_PATTERN with FREE_FILL_PATTERN, and vice versa.)
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Returns true if verification checks out.
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*/
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static bool verify_fill_pattern(void *data, size_t size, bool print_errors, bool expect_free, bool swap_pattern)
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{
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const uint32_t FREE_FILL_WORD = (FREE_FILL_PATTERN << 24) | (FREE_FILL_PATTERN << 16) | (FREE_FILL_PATTERN << 8) | FREE_FILL_PATTERN;
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const uint32_t MALLOC_FILL_WORD = (MALLOC_FILL_PATTERN << 24) | (MALLOC_FILL_PATTERN << 16) | (MALLOC_FILL_PATTERN << 8) | MALLOC_FILL_PATTERN;
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const uint32_t EXPECT_WORD = expect_free ? FREE_FILL_WORD : MALLOC_FILL_WORD;
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const uint32_t REPLACE_WORD = expect_free ? MALLOC_FILL_WORD : FREE_FILL_WORD;
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bool valid = true;
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/* Use 4-byte operations as much as possible */
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if ((intptr_t)data % 4 == 0) {
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uint32_t *p = data;
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while (size >= 4) {
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if (*p != EXPECT_WORD) {
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if (print_errors) {
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MULTI_HEAP_STDERR_PRINTF("CORRUPT HEAP: Invalid data at %p. Expected 0x%08x got 0x%08x\n", p, EXPECT_WORD, *p);
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}
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valid = false;
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#ifndef NDEBUG
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/* If an assertion is going to fail as soon as we're done verifying the pattern, leave the rest of the
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buffer contents as-is for better post-mortem analysis
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*/
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swap_pattern = false;
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#endif
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}
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if (swap_pattern) {
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*p = REPLACE_WORD;
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}
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p++;
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size -= 4;
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}
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data = p;
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}
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uint8_t *p = data;
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for (int i = 0; i < size; i++) {
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if (p[i] != (uint8_t)EXPECT_WORD) {
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if (print_errors) {
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MULTI_HEAP_STDERR_PRINTF("CORRUPT HEAP: Invalid data at %p. Expected 0x%02x got 0x%02x\n", p, (uint8_t)EXPECT_WORD, *p);
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}
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valid = false;
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#ifndef NDEBUG
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swap_pattern = false; // same as above
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#endif
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}
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if (swap_pattern) {
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p[i] = (uint8_t)REPLACE_WORD;
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}
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}
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return valid;
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}
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#endif
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void *multi_heap_malloc(multi_heap_handle_t heap, size_t size)
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{
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if(size > SIZE_MAX - POISON_OVERHEAD) {
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return NULL;
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}
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multi_heap_internal_lock(heap);
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poison_head_t *head = multi_heap_malloc_impl(heap, size + POISON_OVERHEAD);
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uint8_t *data = NULL;
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if (head != NULL) {
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data = poison_allocated_region(head, size);
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#ifdef SLOW
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/* check everything we got back is FREE_FILL_PATTERN & swap for MALLOC_FILL_PATTERN */
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bool ret = verify_fill_pattern(data, size, true, true, true);
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assert( ret );
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#endif
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}
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multi_heap_internal_unlock(heap);
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return data;
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}
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void multi_heap_free(multi_heap_handle_t heap, void *p)
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{
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if (p == NULL) {
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return;
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}
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multi_heap_internal_lock(heap);
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poison_head_t *head = verify_allocated_region(p, true);
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assert(head != NULL);
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#ifdef SLOW
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/* replace everything with FREE_FILL_PATTERN, including the poison head/tail */
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memset(head, FREE_FILL_PATTERN,
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head->alloc_size + POISON_OVERHEAD);
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#endif
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multi_heap_free_impl(heap, head);
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multi_heap_internal_unlock(heap);
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}
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void *multi_heap_realloc(multi_heap_handle_t heap, void *p, size_t size)
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{
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poison_head_t *head = NULL;
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poison_head_t *new_head;
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void *result = NULL;
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if(size > SIZE_MAX - POISON_OVERHEAD) {
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return NULL;
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}
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if (p == NULL) {
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return multi_heap_malloc(heap, size);
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}
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if (size == 0) {
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multi_heap_free(heap, p);
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return NULL;
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}
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/* p != NULL, size != 0 */
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head = verify_allocated_region(p, true);
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assert(head != NULL);
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multi_heap_internal_lock(heap);
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#ifndef SLOW
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new_head = multi_heap_realloc_impl(heap, head, size + POISON_OVERHEAD);
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if (new_head != NULL) {
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/* For "fast" poisoning, we only overwrite the head/tail of the new block so it's safe
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to poison, so no problem doing this even if realloc resized in place.
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*/
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result = poison_allocated_region(new_head, size);
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}
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#else // SLOW
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/* When slow poisoning is enabled, it becomes very fiddly to try and correctly fill memory when resizing in place
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(where the buffer may be moved (including to an overlapping address with the old buffer), grown, or shrunk in
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place.)
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For now we just malloc a new buffer, copy, and free. :|
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Note: If this ever changes, multi_heap defrag realloc test should be enabled.
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*/
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size_t orig_alloc_size = head->alloc_size;
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new_head = multi_heap_malloc_impl(heap, size + POISON_OVERHEAD);
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if (new_head != NULL) {
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result = poison_allocated_region(new_head, size);
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memcpy(result, p, MIN(size, orig_alloc_size));
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multi_heap_free(heap, p);
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}
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#endif
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multi_heap_internal_unlock(heap);
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return result;
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}
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void *multi_heap_get_block_address(multi_heap_block_handle_t block)
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{
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char *head = multi_heap_get_block_address_impl(block);
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return head + sizeof(poison_head_t);
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}
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size_t multi_heap_get_allocated_size(multi_heap_handle_t heap, void *p)
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{
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poison_head_t *head = verify_allocated_region(p, true);
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assert(head != NULL);
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size_t result = multi_heap_get_allocated_size_impl(heap, head);
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if (result > 0) {
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return result - POISON_OVERHEAD;
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}
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return 0;
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}
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void *multi_heap_get_block_owner(multi_heap_block_handle_t block)
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{
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return MULTI_HEAP_GET_BLOCK_OWNER((poison_head_t*)multi_heap_get_block_address_impl(block));
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}
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multi_heap_handle_t multi_heap_register(void *start, size_t size)
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{
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if (start != NULL) {
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memset(start, FREE_FILL_PATTERN, size);
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}
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return multi_heap_register_impl(start, size);
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}
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static inline void subtract_poison_overhead(size_t *arg) {
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if (*arg > POISON_OVERHEAD) {
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*arg -= POISON_OVERHEAD;
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} else {
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*arg = 0;
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}
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}
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void multi_heap_get_info(multi_heap_handle_t heap, multi_heap_info_t *info)
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{
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multi_heap_get_info_impl(heap, info);
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/* don't count the heap poison head & tail overhead in the allocated bytes size */
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info->total_allocated_bytes -= info->allocated_blocks * POISON_OVERHEAD;
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/* trim largest_free_block to account for poison overhead */
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subtract_poison_overhead(&info->largest_free_block);
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/* similarly, trim total_free_bytes so there's no suggestion that
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a block this big may be available. */
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subtract_poison_overhead(&info->total_free_bytes);
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subtract_poison_overhead(&info->minimum_free_bytes);
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}
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size_t multi_heap_free_size(multi_heap_handle_t heap)
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{
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size_t r = multi_heap_free_size_impl(heap);
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subtract_poison_overhead(&r);
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return r;
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}
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size_t multi_heap_minimum_free_size(multi_heap_handle_t heap)
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{
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size_t r = multi_heap_minimum_free_size_impl(heap);
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subtract_poison_overhead(&r);
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return r;
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}
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/* Internal hooks used by multi_heap to manage poisoning, while keeping some modularity */
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bool multi_heap_internal_check_block_poisoning(void *start, size_t size, bool is_free, bool print_errors)
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{
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if (is_free) {
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#ifdef SLOW
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return verify_fill_pattern(start, size, print_errors, true, false);
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#else
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return true; /* can only verify empty blocks in SLOW mode */
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#endif
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} else {
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void *data = (void *)((intptr_t)start + sizeof(poison_head_t));
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poison_head_t *head = verify_allocated_region(data, print_errors);
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if (head != NULL && head->alloc_size > size - POISON_OVERHEAD) {
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/* block can be bigger than alloc_size, for reasons of alignment & fragmentation,
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but block can never be smaller than head->alloc_size... */
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if (print_errors) {
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MULTI_HEAP_STDERR_PRINTF("CORRUPT HEAP: Size at %p expected <=0x%08x got 0x%08x\n", &head->alloc_size,
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size - POISON_OVERHEAD, head->alloc_size);
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}
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return false;
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}
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return head != NULL;
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}
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}
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void multi_heap_internal_poison_fill_region(void *start, size_t size, bool is_free)
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{
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memset(start, is_free ? FREE_FILL_PATTERN : MALLOC_FILL_PATTERN, size);
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}
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#else // !MULTI_HEAP_POISONING
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#ifdef MULTI_HEAP_POISONING_SLOW
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#error "MULTI_HEAP_POISONING_SLOW requires MULTI_HEAP_POISONING"
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#endif
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#endif // MULTI_HEAP_POISONING
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