/*
american fuzzy lop++ - error-checking, memory-zeroing alloc routines
--------------------------------------------------------------------
Originally written by Michal Zalewski
Now maintained by Marc Heuse <mh@mh-sec.de>,
Heiko Eißfeldt <heiko.eissfeldt@hexco.de> and
Andrea Fioraldi <andreafioraldi@gmail.com>
Copyright 2016, 2017 Google Inc. All rights reserved.
Copyright 2019-2020 AFLplusplus Project. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at:
http://www.apache.org/licenses/LICENSE-2.0
This allocator is not designed to resist malicious attackers (the canaries
are small and predictable), but provides a robust and portable way to detect
use-after-free, off-by-one writes, stale pointers, and so on.
*/
#ifndef _HAVE_ALLOC_INL_H
#define _HAVE_ALLOC_INL_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "config.h"
#include "types.h"
#include "debug.h"
/* User-facing macro to sprintf() to a dynamically allocated buffer. */
#define alloc_printf(_str...) \
({ \
\
u8* _tmp; \
s32 _len = snprintf(NULL, 0, _str); \
if (_len < 0) FATAL("Whoa, snprintf() fails?!"); \
_tmp = ck_alloc(_len + 1); \
snprintf((char*)_tmp, _len + 1, _str); \
_tmp; \
\
})
/* Macro to enforce allocation limits as a last-resort defense against
integer overflows. */
#define ALLOC_CHECK_SIZE(_s) \
do { \
\
if ((_s) > MAX_ALLOC) ABORT("Bad alloc request: %u bytes", (_s)); \
\
} while (0)
/* Macro to check malloc() failures and the like. */
#define ALLOC_CHECK_RESULT(_r, _s) \
do { \
\
if (!(_r)) ABORT("Out of memory: can't allocate %u bytes", (_s)); \
\
} while (0)
/* Magic tokens used to mark used / freed chunks. */
#define ALLOC_MAGIC_C1 0xFF00FF00 /* Used head (dword) */
#define ALLOC_MAGIC_F 0xFE00FE00 /* Freed head (dword) */
#define ALLOC_MAGIC_C2 0xF0 /* Used tail (byte) */
/* Positions of guard tokens in relation to the user-visible pointer. */
#define ALLOC_C1(_ptr) (((u32*)(_ptr))[-2])
#define ALLOC_S(_ptr) (((u32*)(_ptr))[-1])
#define ALLOC_C2(_ptr) (((u8*)(_ptr))[ALLOC_S(_ptr)])
#define ALLOC_OFF_HEAD 8
#define ALLOC_OFF_TOTAL (ALLOC_OFF_HEAD + 1)
/* Allocator increments for ck_realloc_block(). */
#define ALLOC_BLK_INC 256
/* Sanity-checking macros for pointers. */
#define CHECK_PTR(_p) \
do { \
\
if (_p) { \
\
if (ALLOC_C1(_p) ^ ALLOC_MAGIC_C1) { \
\
if (ALLOC_C1(_p) == ALLOC_MAGIC_F) \
ABORT("Use after free."); \
else \
ABORT("Corrupted head alloc canary."); \
\
} \
\
} \
\
} while (0)
/* #define CHECK_PTR(_p) do { \
if (_p) { \
if (ALLOC_C1(_p) ^ ALLOC_MAGIC_C1) {\
if (ALLOC_C1(_p) == ALLOC_MAGIC_F) \
ABORT("Use after free."); \
else ABORT("Corrupted head alloc canary."); \
} \
if (ALLOC_C2(_p) ^ ALLOC_MAGIC_C2) \
ABORT("Corrupted tail alloc canary."); \
} \
} while (0)
*/
#define CHECK_PTR_EXPR(_p) \
({ \
\
typeof(_p) _tmp = (_p); \
CHECK_PTR(_tmp); \
_tmp; \
\
})
/* Allocate a buffer, explicitly not zeroing it. Returns NULL for zero-sized
requests. */
static inline void* DFL_ck_alloc_nozero(u32 size) {
u8* ret;
if (!size) return NULL;
ALLOC_CHECK_SIZE(size);
ret = malloc(size + ALLOC_OFF_TOTAL);
ALLOC_CHECK_RESULT(ret, size);
ret += ALLOC_OFF_HEAD;
ALLOC_C1(ret) = ALLOC_MAGIC_C1;
ALLOC_S(ret) = size;
ALLOC_C2(ret) = ALLOC_MAGIC_C2;
return (void*)ret;
}
/* Allocate a buffer, returning zeroed memory. */
static inline void* DFL_ck_alloc(u32 size) {
void* mem;
if (!size) return NULL;
mem = DFL_ck_alloc_nozero(size);
return memset(mem, 0, size);
}
/* Free memory, checking for double free and corrupted heap. When DEBUG_BUILD
is set, the old memory will be also clobbered with 0xFF. */
static inline void DFL_ck_free(void* mem) {
if (!mem) return;
CHECK_PTR(mem);
#ifdef DEBUG_BUILD
/* Catch pointer issues sooner. */
memset(mem, 0xFF, ALLOC_S(mem));
#endif /* DEBUG_BUILD */
ALLOC_C1(mem) = ALLOC_MAGIC_F;
u8* realStart = mem;
free(realStart - ALLOC_OFF_HEAD);
}
/* Re-allocate a buffer, checking for issues and zeroing any newly-added tail.
With DEBUG_BUILD, the buffer is always reallocated to a new addresses and the
old memory is clobbered with 0xFF. */
static inline void* DFL_ck_realloc(void* orig, u32 size) {
u8* ret;
u32 old_size = 0;
if (!size) {
DFL_ck_free(orig);
return NULL;
}
if (orig) {
CHECK_PTR(orig);
#ifndef DEBUG_BUILD
ALLOC_C1(orig) = ALLOC_MAGIC_F;
#endif /* !DEBUG_BUILD */
old_size = ALLOC_S(orig);
u8* origu8 = orig;
origu8 -= ALLOC_OFF_HEAD;
orig = origu8;
ALLOC_CHECK_SIZE(old_size);
}
ALLOC_CHECK_SIZE(size);
#ifndef DEBUG_BUILD
ret = realloc(orig, size + ALLOC_OFF_TOTAL);
ALLOC_CHECK_RESULT(ret, size);
#else
/* Catch pointer issues sooner: force relocation and make sure that the
original buffer is wiped. */
ret = malloc(size + ALLOC_OFF_TOTAL);
ALLOC_CHECK_RESULT(ret, size);
if (orig) {
u8* origu8 = orig;
memcpy(ret + ALLOC_OFF_HEAD, origu8 + ALLOC_OFF_HEAD, MIN(size, old_size));
memset(origu8 + ALLOC_OFF_HEAD, 0xFF, old_size);
ALLOC_C1(origu8 + ALLOC_OFF_HEAD) = ALLOC_MAGIC_F;
free(orig);
}
#endif /* ^!DEBUG_BUILD */
ret += ALLOC_OFF_HEAD;
ALLOC_C1(ret) = ALLOC_MAGIC_C1;
ALLOC_S(ret) = size;
ALLOC_C2(ret) = ALLOC_MAGIC_C2;
if (size > old_size) memset(ret + old_size, 0, size - old_size);
return (void*)ret;
}
/* Re-allocate a buffer with ALLOC_BLK_INC increments (used to speed up
repeated small reallocs without complicating the user code). */
static inline void* DFL_ck_realloc_block(void* orig, u32 size) {
#ifndef DEBUG_BUILD
if (orig) {
CHECK_PTR(orig);
if (ALLOC_S(orig) >= size) return orig;
size += ALLOC_BLK_INC;
}
#endif /* !DEBUG_BUILD */
return DFL_ck_realloc(orig, size);
}
/* Create a buffer with a copy of a string. Returns NULL for NULL inputs. */
static inline u8* DFL_ck_strdup(u8* str) {
u8* ret;
u32 size;
if (!str) return NULL;
size = strlen((char*)str) + 1;
ALLOC_CHECK_SIZE(size);
ret = malloc(size + ALLOC_OFF_TOTAL);
ALLOC_CHECK_RESULT(ret, size);
ret += ALLOC_OFF_HEAD;
ALLOC_C1(ret) = ALLOC_MAGIC_C1;
ALLOC_S(ret) = size;
ALLOC_C2(ret) = ALLOC_MAGIC_C2;
return memcpy(ret, str, size);
}
/* Create a buffer with a copy of a memory block. Returns NULL for zero-sized
or NULL inputs. */
static inline void* DFL_ck_memdup(void* mem, u32 size) {
u8* ret;
if (!mem || !size) return NULL;
ALLOC_CHECK_SIZE(size);
ret = malloc(size + ALLOC_OFF_TOTAL);
ALLOC_CHECK_RESULT(ret, size);
ret += ALLOC_OFF_HEAD;
ALLOC_C1(ret) = ALLOC_MAGIC_C1;
ALLOC_S(ret) = size;
ALLOC_C2(ret) = ALLOC_MAGIC_C2;
return memcpy(ret, mem, size);
}
/* Create a buffer with a block of text, appending a NUL terminator at the end.
Returns NULL for zero-sized or NULL inputs. */
static inline u8* DFL_ck_memdup_str(u8* mem, u32 size) {
u8* ret;
if (!mem || !size) return NULL;
ALLOC_CHECK_SIZE(size);
ret = malloc(size + ALLOC_OFF_TOTAL + 1);
ALLOC_CHECK_RESULT(ret, size);
ret += ALLOC_OFF_HEAD;
ALLOC_C1(ret) = ALLOC_MAGIC_C1;
ALLOC_S(ret) = size;
ALLOC_C2(ret) = ALLOC_MAGIC_C2;
memcpy(ret, mem, size);
ret[size] = 0;
return ret;
}
#ifndef DEBUG_BUILD
/* In non-debug mode, we just do straightforward aliasing of the above functions
to user-visible names such as ck_alloc(). */
#define ck_alloc DFL_ck_alloc
#define ck_alloc_nozero DFL_ck_alloc_nozero
#define ck_realloc DFL_ck_realloc
#define ck_realloc_block DFL_ck_realloc_block
#define ck_strdup DFL_ck_strdup
#define ck_memdup DFL_ck_memdup
#define ck_memdup_str DFL_ck_memdup_str
#define ck_free DFL_ck_free
#define alloc_report()
#else
/* In debugging mode, we also track allocations to detect memory leaks, and the
flow goes through one more layer of indirection. */
/* Alloc tracking data structures: */
#define ALLOC_BUCKETS 4096
struct TRK_obj {
void* ptr;
char *file, *func;
u32 line;
};
#ifdef AFL_MAIN
struct TRK_obj* TRK[ALLOC_BUCKETS];
u32 TRK_cnt[ALLOC_BUCKETS];
#define alloc_report() TRK_report()
#else
extern struct TRK_obj* TRK[ALLOC_BUCKETS];
extern u32 TRK_cnt[ALLOC_BUCKETS];
#define alloc_report()
#endif /* ^AFL_MAIN */
/* Bucket-assigning function for a given pointer: */
#define TRKH(_ptr) (((((u32)(_ptr)) >> 16) ^ ((u32)(_ptr))) % ALLOC_BUCKETS)
/* Add a new entry to the list of allocated objects. */
static inline void TRK_alloc_buf(void* ptr, const char* file, const char* func,
u32 line) {
u32 i, bucket;
if (!ptr) return;
bucket = TRKH(ptr);
/* Find a free slot in the list of entries for that bucket. */
for (i = 0; i < TRK_cnt[bucket]; i++)
if (!TRK[bucket][i].ptr) {
TRK[bucket][i].ptr = ptr;
TRK[bucket][i].file = (char*)file;
TRK[bucket][i].func = (char*)func;
TRK[bucket][i].line = line;
return;
}
/* No space available - allocate more. */
TRK[bucket] = DFL_ck_realloc_block(
TRK[bucket], (TRK_cnt[bucket] + 1) * sizeof(struct TRK_obj));
TRK[bucket][i].ptr = ptr;
TRK[bucket][i].file = (char*)file;
TRK[bucket][i].func = (char*)func;
TRK[bucket][i].line = line;
TRK_cnt[bucket]++;
}
/* Remove entry from the list of allocated objects. */
static inline void TRK_free_buf(void* ptr, const char* file, const char* func,
u32 line) {
u32 i, bucket;
if (!ptr) return;
bucket = TRKH(ptr);
/* Find the element on the list... */
for (i = 0; i < TRK_cnt[bucket]; i++)
if (TRK[bucket][i].ptr == ptr) {
TRK[bucket][i].ptr = 0;
return;
}
WARNF("ALLOC: Attempt to free non-allocated memory in %s (%s:%u)", func, file,
line);
}
/* Do a final report on all non-deallocated objects. */
static inline void TRK_report(void) {
u32 i, bucket;
fflush(0);
for (bucket = 0; bucket < ALLOC_BUCKETS; bucket++)
for (i = 0; i < TRK_cnt[bucket]; i++)
if (TRK[bucket][i].ptr)
WARNF("ALLOC: Memory never freed, created in %s (%s:%u)",
TRK[bucket][i].func, TRK[bucket][i].file, TRK[bucket][i].line);
}
/* Simple wrappers for non-debugging functions: */
static inline void* TRK_ck_alloc(u32 size, const char* file, const char* func,
u32 line) {
void* ret = DFL_ck_alloc(size);
TRK_alloc_buf(ret, file, func, line);
return ret;
}
static inline void* TRK_ck_realloc(void* orig, u32 size, const char* file,
const char* func, u32 line) {
void* ret = DFL_ck_realloc(orig, size);
TRK_free_buf(orig, file, func, line);
TRK_alloc_buf(ret, file, func, line);
return ret;
}
static inline void* TRK_ck_realloc_block(void* orig, u32 size, const char* file,
const char* func, u32 line) {
void* ret = DFL_ck_realloc_block(orig, size);
TRK_free_buf(orig, file, func, line);
TRK_alloc_buf(ret, file, func, line);
return ret;
}
static inline void* TRK_ck_strdup(u8* str, const char* file, const char* func,
u32 line) {
void* ret = DFL_ck_strdup(str);
TRK_alloc_buf(ret, file, func, line);
return ret;
}
static inline void* TRK_ck_memdup(void* mem, u32 size, const char* file,
const char* func, u32 line) {
void* ret = DFL_ck_memdup(mem, size);
TRK_alloc_buf(ret, file, func, line);
return ret;
}
static inline void* TRK_ck_memdup_str(void* mem, u32 size, const char* file,
const char* func, u32 line) {
void* ret = DFL_ck_memdup_str(mem, size);
TRK_alloc_buf(ret, file, func, line);
return ret;
}
static inline void TRK_ck_free(void* ptr, const char* file, const char* func,
u32 line) {
TRK_free_buf(ptr, file, func, line);
DFL_ck_free(ptr);
}
/* Aliasing user-facing names to tracking functions: */
#define ck_alloc(_p1) TRK_ck_alloc(_p1, __FILE__, __FUNCTION__, __LINE__)
#define ck_alloc_nozero(_p1) TRK_ck_alloc(_p1, __FILE__, __FUNCTION__, __LINE__)
#define ck_realloc(_p1, _p2) \
TRK_ck_realloc(_p1, _p2, __FILE__, __FUNCTION__, __LINE__)
#define ck_realloc_block(_p1, _p2) \
TRK_ck_realloc_block(_p1, _p2, __FILE__, __FUNCTION__, __LINE__)
#define ck_strdup(_p1) TRK_ck_strdup(_p1, __FILE__, __FUNCTION__, __LINE__)
#define ck_memdup(_p1, _p2) \
TRK_ck_memdup(_p1, _p2, __FILE__, __FUNCTION__, __LINE__)
#define ck_memdup_str(_p1, _p2) \
TRK_ck_memdup_str(_p1, _p2, __FILE__, __FUNCTION__, __LINE__)
#define ck_free(_p1) TRK_ck_free(_p1, __FILE__, __FUNCTION__, __LINE__)
#endif /* ^!DEBUG_BUILD */
#endif /* ! _HAVE_ALLOC_INL_H */
