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afl-fuzz.c
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/*
american fuzzy lop - fuzzer code
--------------------------------
Written and maintained by Michal Zalewski <[email protected]>
Forkserver design by Jann Horn <[email protected]>
Copyright 2013, 2014, 2015, 2016, 2017 Google Inc. 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 is the real deal: the program takes an instrumented binary and
attempts a variety of basic fuzzing tricks, paying close attention to
how they affect the execution path.
*/
/*
该文件的主要作用是通过不断变异测试用例来影响程序的执行路径。
在功能上，可以总体上分为3部分：
1. 初始配置：进行fuzz环境配置相关工作
2. fuzz执行：fuzz的主循环过程
3. 变异策略：测试用例的变异过程和方式
*/
#define AFL_MAIN
#define MESSAGES_TO_STDOUT
#define _GNU_SOURCE
#define _FILE_OFFSET_BITS 64
//下面五个头文件是自定义头文件
//配置文件，包含各种宏定义，属于通用配置。比如bitflip变异时收集的token的长度和数量会在此文件中进行定义。
#include "config.h"
//类型重定义，一些在 afl-fuzz.c 中看不太懂的类型，可以在这里看看是不是有相关定义，比如 u8 在源码中经常出现，
//实际上在这个头文件可以看出 typedef uint8_t u8，所以其对应的类型应该是 uint8_t ，对应的是 C99 标准里的无符号字符型。
#include "types.h"
//调试，宏定义各种参数及函数，比如显示的颜色，还有各种自定义的函数，如果改AFL，这些东西相当于没有编译器情况下的 "高端
// printf(滑稽脸)"，比如最常见的 OKF("We're done here. Have a nice day!\n"); 其中的 OKF 就是一个输出代表成功信息的函数
#include "debug.h"
//内存相关，提供错误检查、内存清零、内存分配等常规操作，“内存器的设计初衷不是为了抵抗恶意攻击，但是它确实提供了便携健壮的
//内存处理方式，可以检查 use-after-free 等”
#include "alloc-inl.h"
//哈希函数，文件中实现一个参数为 const void* key, u32 len, u32 seed 返回为 u32 的静态内联函数
#include "hash.h"
//标准库头文件，基本和widonws下c编程一样，仅个别是linux c才会用到
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <signal.h>
#include <dirent.h> //文件操作相关，此处可以参考afl-tmin.c文件中的修改，查看其具体用途
#include <ctype.h>
#include <fcntl.h>
#include <termios.h>
#include <dlfcn.h>
#include <sched.h> //任务调度相关
// Linux C编程特有的头文件
//这一部分，引用了一些Linux环境下的特殊头文件，跟上一部分会有一些重叠，但是各司其职，实际编程
//两边的函数都可以，但是偏向于用这部分。
//对应Linux环境的头文件位置 /usr/include/sys/
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/shm.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/resource.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/file.h>
//环境判断预处理
#if defined(__APPLE__) || defined(__FreeBSD__) || defined(__OpenBSD__)
#include <sys/sysctl.h>
#endif /* __APPLE__ || __FreeBSD__ || __OpenBSD__ */
/* For systems that have sched_setaffinity; right now just Linux, but one
can hope... */
// Linux环境下独有的宏定义
#ifdef __linux__
#define HAVE_AFFINITY 1 // affinity 亲和性，跟cpu的亲和性，与与运行性能有关。定义之后共出现了五次。
#endif /* __linux__ */
/* A toggle to export some variables when building as a library. Not very
useful for the general public. */
//不常用，当afl被编译成库的时候，用来保证变量的输出。
#ifdef AFL_LIB
#define EXP_ST
#else
#define EXP_ST static
#endif /* ^AFL_LIB */
/* Lots of globals, but mostly for the status UI and other things where it
really makes no sense to haul them around as function parameters. */
EXP_ST u8 *in_dir, /* Input directory with test cases */
*out_file, /* File to fuzz, if any */
*out_dir, /* Working & output directory */
*sync_dir, /* Synchronization directory */
*sync_id, /* Fuzzer ID */
*use_banner, /* Display banner(横幅) */
*in_bitmap, /* Input bitmap */
*doc_path, /* Path to documentation dir */
*target_path, /* Path to target binary */
*orig_cmdline, /* Original command line */
*old_out_dir; /* 新添加的字段，用于保存fuzz停止时out文件夹利里有价值的种子, 当出现 out 文件夹比较有用时旧的文件保存 */
EXP_ST u32 exec_tmout = EXEC_TIMEOUT; /* Configurable exec timeout (ms) */
static u32 hang_tmout = EXEC_TIMEOUT; /* Timeout used for hang det (ms) */
EXP_ST u64 mem_limit = MEM_LIMIT; /* Memory cap for child (MB) */
static u32 stats_update_freq = 1; /* Stats update frequency (execs) */
EXP_ST u8 skip_deterministic, /* Skip deterministic stages? */
force_deterministic, /* Force deterministic stages? */
use_splicing, /* Recombine input files? */
dumb_mode, /* Run in non-instrumented mode? dumb mode:盲目变异，不插桩。非dumb mode（-d）*/
score_changed, /* Scoring for favorites changed? */
kill_signal, /* Signal that killed the child */
resuming_fuzz, /* Resuming an older fuzzing job? */
timeout_given, /* Specific timeout given? */
not_on_tty, /* stdout is not a tty */
term_too_small, /* terminal dimensions too small */
uses_asan, /* Target uses ASAN? */
no_forkserver, /* Disable forkserver? */
crash_mode, /* Crash mode! Yeah! */
in_place_resume, /* Attempt in-place resume? */
auto_changed, /* Auto-generated tokens changed? */
no_cpu_meter_red, /* Feng shui on the status screen */
no_arith, /* Skip most arithmetic ops */
shuffle_queue, /* Shuffle input queue? */
bitmap_changed = 1, /* Time to update bitmap? */
qemu_mode, /* Running in QEMU mode? */
skip_requested, /* Skip request, via SIGUSR1 */
run_over10m, /* Run time over 10 minutes? */
persistent_mode, /* Running in persistent mode? */
deferred_mode, /* Deferred forkserver mode? */
fast_cal; /* Try to calibrate faster? */
static s32 out_fd, /* Persistent fd for out_file */
dev_urandom_fd = -1, /* Persistent fd for /dev/urandom */
dev_null_fd = -1, /* Persistent fd for /dev/null */
fsrv_ctl_fd, /* Fork server control pipe (write) */
fsrv_st_fd; /* Fork server status pipe (read) */
static s32 forksrv_pid, /* PID of the fork server */
child_pid = -1, /* PID of the fuzzed program */
out_dir_fd = -1; /* FD of the lock file */
// AFL是根据二元tuple(跳转的源地址和目标地址)来记录分支信息，从而获取target的执行流程和代码覆盖情况.tuple信息：目标程序执行路径
EXP_ST u8 *trace_bits; /* SHM with instrumentation bitmap 记录当前的tuple信息*/
EXP_ST u8 virgin_bits[MAP_SIZE], /* Regions yet untouched by fuzzing 记录总的tuple信息*/
virgin_tmout[MAP_SIZE], /* Bits we haven't seen in tmouts 记录fuzz过程中出现的所有目标程序的timeout时的tuple信息*/
virgin_crash[MAP_SIZE]; /* Bits we haven't seen in crashes 记录fuzz过程中出现的crash时的tuple信息*/
static u8 var_bytes[MAP_SIZE]; /* Bytes that appear to be variable */
static s32 shm_id; /* ID of the SHM region */
static volatile u8 stop_soon, /* Ctrl-C pressed? */
clear_screen = 1, /* Window resized? */
child_timed_out; /* Traced process timed out? */
EXP_ST u32 queued_paths, /* Total number of queued testcases */
queued_variable, /* Testcases with variable behavior */
queued_at_start, /* Total number of initial inputs */
queued_discovered, /* Items discovered during this run */
queued_imported, /* Items imported via -S */
queued_favored, /* Paths deemed favorable */
queued_with_cov, /* Paths with new coverage bytes */
pending_not_fuzzed, /* Queued but not done yet */
pending_favored, /* Pending favored paths */
cur_skipped_paths, /* Abandoned inputs in cur cycle */
cur_depth, /* Current path depth */
max_depth, /* Max path depth */
useless_at_start, /* Number of useless starting paths */
var_byte_count, /* Bitmap bytes with var behavior */
current_entry, /* Current queue entry ID */
havoc_div = 1; /* Cycle count divisor for havoc */
EXP_ST u64 total_crashes, /* Total number of crashes */
unique_crashes, /* Crashes with unique signatures */
total_tmouts, /* Total number of timeouts */
unique_tmouts, /* Timeouts with unique signatures */
unique_hangs, /* Hangs with unique signatures */
total_execs, /* Total execve() calls */
start_time, /* Unix start time (ms) */
last_path_time, /* Time for most recent path (ms) */
last_crash_time, /* Time for most recent crash (ms) */
last_hang_time, /* Time for most recent hang (ms) */
last_crash_execs, /* Exec counter at last crash */
queue_cycle, /* Queue round counter */
cycles_wo_finds, /* Cycles without any new paths */
trim_execs, /* Execs done to trim input files */
bytes_trim_in, /* Bytes coming into the trimmer */
bytes_trim_out, /* Bytes coming outa the trimmer */
blocks_eff_total, /* Blocks subject to effector maps */
blocks_eff_select; /* Blocks selected as fuzzable */
static u32 subseq_tmouts; /* Number of timeouts in a row */
static u8 *stage_name = "init", /* Name of the current fuzz stage */
*stage_short, /* Short stage name */
*syncing_party; /* Currently syncing with... */
static s32 stage_cur, stage_max; /* Stage progression */
static s32 splicing_with = -1; /* Splicing with which test case? */
static u32 master_id, master_max; /* Master instance job splitting */
static u32 syncing_case; /* Syncing with case #... */
static s32 stage_cur_byte, /* Byte offset of current stage op */
stage_cur_val; /* Value used for stage op */
static u8 stage_val_type; /* Value type (STAGE_VAL_*) */
static u64 stage_finds[32], /* Patterns found per fuzz stage */
stage_cycles[32]; /* Execs per fuzz stage */
static u32 rand_cnt; /* Random number counter */
static u64 total_cal_us, /* Total calibration time (us) */
total_cal_cycles; /* Total calibration cycles */
static u64 total_bitmap_size, /* Total bit count for all bitmaps */
total_bitmap_entries; /* Number of bitmaps counted */
static s32 cpu_core_count; /* CPU core count */
#ifdef HAVE_AFFINITY
//因为是特定条件下的宏定义，所以也可以当是跟cpu操作相关的bool用，都是成对出现。
static s32 cpu_aff = -1; /* Selected CPU core */
//只有在启用这种亲和性的情况下，才会定义 cpu_aff 用来标记选择的cpu核。
#endif /* HAVE_AFFINITY */
static FILE *plot_file; /* Gnuplot output file */
struct queue_entry
{
u8 *fname; /* File name for the test case 测试用例的文件名 */
u32 len; /* Input length testcase大小 */
u8 cal_failed, /* Calibration failed? 标准失败 */
trim_done, /* Trimmed? 该testcase是否被修建 */
was_fuzzed, /* Had any fuzzing done yet? 是否已经经过fuzzing */
passed_det, /* Deterministic stages passed? */
has_new_cov, /* Triggers new coverage? 当前测试用例是否触发了新的覆盖率 */
var_behavior, /* Variable behavior? 目标程序多次运行表现是否一致*/
favored, /* Currently favored? 当前是否被标记为favored（更多的fuzz机会） */
fs_redundant; /* Marked as redundant in the fs? */
u32 bitmap_size, /* Number of bits set in bitmap 共享数组中非0项的个数/bitmap中bit的数量 */
exec_cksum; /* Checksum of the execution trace 共享数组的哈希值*/
u64 exec_us, /* Execution time (us) 当前测试用例的执行时间（经过校准得到的平均值）*/
handicap, /* Number of queue cycles behind */
depth; /* Path depth 路径深度 */
u8 *trace_mini; /* Trace bytes, if kept 1个bit存一个byte的trace_bits。对当前测试用例对应共享数组的压缩版本，省略了hit count信息*/
u32 tc_ref; /* Trace bytes ref count top_rate[]中该testcase入选的次数。以该样例作为最优样例的分支点的数目 */
struct queue_entry *next, /* Next element, if any 队列下一结点 */
*next_100; /* 100 elements ahead */
};
static struct queue_entry *queue, /* Fuzzing queue (linked list) */
*queue_cur, /* Current offset within the queue */
*queue_top, /* Top of the list */
*q_prev100; /* Previous 100 marker */
//一条边可能被多个testcase执行，而这些testcase的长度和运行时间基本是不同的。
//top_rated[index]表示在众多执行了edge-index的testcase中、长度*运行时间最短的那个testcase（我们称这个testcase更favored的）
//top_rated数组的索引和trace_bits数组的索引所代表的含义是一致的，都代表边
static struct queue_entry *
top_rated[MAP_SIZE]; /* Top entries for bitmap bytes */
struct extra_data
{
u8 *data; /* Dictionary token data */
u32 len; /* Dictionary token length */
u32 hit_cnt; /* Use count in the corpus */
};
static struct extra_data *extras; /* Extra tokens to fuzz with */
static u32 extras_cnt; /* Total number of tokens read */
static struct extra_data *a_extras; /* Automatically selected extras */
static u32 a_extras_cnt; /* Total number of tokens available */
static u8 *(*post_handler)(u8 *buf, u32 *len);
/* Interesting values, as per config.h */
static s8 interesting_8[] = {INTERESTING_8};
static s16 interesting_16[] = {INTERESTING_8, INTERESTING_16};
static s32 interesting_32[] = {INTERESTING_8, INTERESTING_16, INTERESTING_32};
/* Fuzzing stages */
// fuzzing状态，这里包含了很多不同fuzz种子的变异策略。使用枚举可以避免使用数组时还需要解释数组下标的含义。
enum
{
/* 00 */ STAGE_FLIP1,
/* 01 */ STAGE_FLIP2,
/* 02 */ STAGE_FLIP4,
/* 03 */ STAGE_FLIP8,
/* 04 */ STAGE_FLIP16,
/* 05 */ STAGE_FLIP32,
/* 06 */ STAGE_ARITH8,
/* 07 */ STAGE_ARITH16,
/* 08 */ STAGE_ARITH32,
/* 09 */ STAGE_INTEREST8,
/* 10 */ STAGE_INTEREST16,
/* 11 */ STAGE_INTEREST32,
/* 12 */ STAGE_EXTRAS_UO,
/* 13 */ STAGE_EXTRAS_UI,
/* 14 */ STAGE_EXTRAS_AO,
/* 15 */ STAGE_HAVOC,
/* 16 */ STAGE_SPLICE
};
/* Stage value types */
//状态值的类型，用来辅助、修饰上一个枚举fuzzing状态，用来识别当前的状态枚举对应的变异方式的类型。
enum
{
/* 00 */ STAGE_VAL_NONE,
/* 01 */ STAGE_VAL_LE,
/* 02 */ STAGE_VAL_BE
};
/* Execution status fault codes */
//
enum
{
/* 00 */ FAULT_NONE,
/* 01 */ FAULT_TMOUT,
/* 02 */ FAULT_CRASH,
/* 03 */ FAULT_ERROR,
/* 04 */ FAULT_NOINST,
/* 05 */ FAULT_NOBITS
};
/* Get unix time in milliseconds */
static u64 get_cur_time(void)
{
struct timeval tv;
struct timezone tz;
gettimeofday(&tv, &tz);
return (tv.tv_sec * 1000ULL) + (tv.tv_usec / 1000);
}
/* Get unix time in microseconds */
static u64 get_cur_time_us(void)
{
struct timeval tv;
struct timezone tz;
gettimeofday(&tv, &tz);
return (tv.tv_sec * 1000000ULL) + tv.tv_usec;
}
/* Generate a random number (from 0 to limit - 1). This may
have slight bias. */
static inline u32 UR(u32 limit)
{
if (unlikely(!rand_cnt--))
{
u32 seed[2];
ck_read(dev_urandom_fd, &seed, sizeof(seed), "/dev/urandom");
srandom(seed[0]);
rand_cnt = (RESEED_RNG / 2) + (seed[1] % RESEED_RNG);
}
return random() % limit;
}
/* Shuffle an array of pointers. Might be slightly biased. */
static void shuffle_ptrs(void **ptrs, u32 cnt)
{
u32 i;
for (i = 0; i < cnt - 2; i++)
{
u32 j = i + UR(cnt - i);
void *s = ptrs[i];
ptrs[i] = ptrs[j];
ptrs[j] = s;
}
}
#ifdef HAVE_AFFINITY
/* Build a list of processes bound to specific cores. Returns -1 if nothing
can be found. Assumes an upper bound of 4k CPUs. */
//尝试绑定空闲的cpu
static void bind_to_free_cpu(void)
{
DIR *d;
struct dirent *de;
cpu_set_t c;
u8 cpu_used[4096] = {0};
u32 i;
if (cpu_core_count < 2)
return;
if (getenv("AFL_NO_AFFINITY"))
{
WARNF("Not binding to a CPU core (AFL_NO_AFFINITY set).");
return;
}
d = opendir("/proc");
if (!d)
{
WARNF("Unable to access /proc - can't scan for free CPU cores.");
return;
}
ACTF("Checking CPU core loadout...");
/* Introduce some jitter, in case multiple AFL tasks are doing the same
thing at the same time... */
usleep(R(1000) * 250);
/* Scan all /proc/<pid>/status entries, checking for Cpus_allowed_list.
Flag all processes bound to a specific CPU using cpu_used[]. This will
fail for some exotic binding setups, but is likely good enough in almost
all real-world use cases. */
while ((de = readdir(d)))
{
u8 *fn;
FILE *f;
u8 tmp[MAX_LINE];
u8 has_vmsize = 0;
if (!isdigit(de->d_name[0]))
continue;
fn = alloc_printf("/proc/%s/status", de->d_name);
if (!(f = fopen(fn, "r")))
{
ck_free(fn);
continue;
}
while (fgets(tmp, MAX_LINE, f))
{
u32 hval;
/* Processes without VmSize are probably kernel tasks. */
if (!strncmp(tmp, "VmSize:\t", 8))
has_vmsize = 1;
if (!strncmp(tmp, "Cpus_allowed_list:\t", 19) &&
!strchr(tmp, '-') && !strchr(tmp, ',') &&
sscanf(tmp + 19, "%u", &hval) == 1 && hval < sizeof(cpu_used) &&
has_vmsize)
{
cpu_used[hval] = 1;
break;
}
}
ck_free(fn);
fclose(f);
}
closedir(d);
for (i = 0; i < cpu_core_count; i++)
if (!cpu_used[i])
break;
if (i == cpu_core_count)
{
SAYF("\n" cLRD "[-] " cRST
"Uh-oh, looks like all %u CPU cores on your system are allocated to\n"
" other instances of afl-fuzz (or similar CPU-locked tasks). Starting\n"
" another fuzzer on this machine is probably a bad plan, but if you are\n"
" absolutely sure, you can set AFL_NO_AFFINITY and try again.\n",
cpu_core_count);
FATAL("No more free CPU cores");
}
//获取空闲的cpu，尝试绑定
OKF("Found a free CPU core, binding to #%u.", i);
cpu_aff = i;
CPU_ZERO(&c);
CPU_SET(i, &c);
if (sched_setaffinity(0, sizeof(c), &c))
PFATAL("sched_setaffinity failed");
}
#endif /* HAVE_AFFINITY */
#ifndef IGNORE_FINDS2
/* Helper function to compare buffers; returns first and last differing offset. We
use this to find reasonable locations for splicing two files. */
static void locate_diffs(u8 *ptr1, u8 *ptr2, u32 len, s32 *first, s32 *last)
{
s32 f_loc = -1;
s32 l_loc = -1;
u32 pos;
for (pos = 0; pos < len; pos++)
{
if (*(ptr1++) != *(ptr2++))
{
if (f_loc == -1)
f_loc = pos;
l_loc = pos;
}
}
*first = f_loc;
*last = l_loc;
return;
}
#endif /* !IGNORE_FINDS */
/* Describe integer. Uses 12 cyclic static buffers for return values. The value
returned should be five characters or less for all the integers we reasonably
expect to see. */
static u8 *DI(u64 val)
{
static u8 tmp[12][16];
static u8 cur;
cur = (cur + 1) % 12;
#define CHK_FORMAT(_divisor, _limit_mult, _fmt, _cast) \
do \
{ \
if (val < (_divisor) * (_limit_mult)) \
{ \
sprintf(tmp[cur], _fmt, ((_cast)val) / (_divisor)); \
return tmp[cur]; \
} \
} while (0)
/* 0-9999 */
CHK_FORMAT(1, 10000, "%llu", u64);
/* 10.0k - 99.9k */
CHK_FORMAT(1000, 99.95, "%0.01fk", double);
/* 100k - 999k */
CHK_FORMAT(1000, 1000, "%lluk", u64);
/* 1.00M - 9.99M */
CHK_FORMAT(1000 * 1000, 9.995, "%0.02fM", double);
/* 10.0M - 99.9M */
CHK_FORMAT(1000 * 1000, 99.95, "%0.01fM", double);
/* 100M - 999M */
CHK_FORMAT(1000 * 1000, 1000, "%lluM", u64);
/* 1.00G - 9.99G */
CHK_FORMAT(1000LL * 1000 * 1000, 9.995, "%0.02fG", double);
/* 10.0G - 99.9G */
CHK_FORMAT(1000LL * 1000 * 1000, 99.95, "%0.01fG", double);
/* 100G - 999G */
CHK_FORMAT(1000LL * 1000 * 1000, 1000, "%lluG", u64);
/* 1.00T - 9.99G */
CHK_FORMAT(1000LL * 1000 * 1000 * 1000, 9.995, "%0.02fT", double);
/* 10.0T - 99.9T */
CHK_FORMAT(1000LL * 1000 * 1000 * 1000, 99.95, "%0.01fT", double);
/* 100T+ */
strcpy(tmp[cur], "infty");
return tmp[cur];
}
/* Describe float. Similar to the above, except with a single
static buffer. */
static u8 *DF(double val)
{
static u8 tmp[16];
if (val < 99.995)
{
sprintf(tmp, "%0.02f", val);
return tmp;
}
if (val < 999.95)
{
sprintf(tmp, "%0.01f", val);
return tmp;
}
return DI((u64)val);
}
/* Describe integer as memory size. */
static u8 *DMS(u64 val)
{
static u8 tmp[12][16];
static u8 cur;
cur = (cur + 1) % 12;
/* 0-9999 */
CHK_FORMAT(1, 10000, "%llu B", u64);
/* 10.0k - 99.9k */
CHK_FORMAT(1024, 99.95, "%0.01f kB", double);
/* 100k - 999k */
CHK_FORMAT(1024, 1000, "%llu kB", u64);
/* 1.00M - 9.99M */
CHK_FORMAT(1024 * 1024, 9.995, "%0.02f MB", double);
/* 10.0M - 99.9M */
CHK_FORMAT(1024 * 1024, 99.95, "%0.01f MB", double);
/* 100M - 999M */
CHK_FORMAT(1024 * 1024, 1000, "%llu MB", u64);
/* 1.00G - 9.99G */
CHK_FORMAT(1024LL * 1024 * 1024, 9.995, "%0.02f GB", double);
/* 10.0G - 99.9G */
CHK_FORMAT(1024LL * 1024 * 1024, 99.95, "%0.01f GB", double);
/* 100G - 999G */
CHK_FORMAT(1024LL * 1024 * 1024, 1000, "%llu GB", u64);
/* 1.00T - 9.99G */
CHK_FORMAT(1024LL * 1024 * 1024 * 1024, 9.995, "%0.02f TB", double);
/* 10.0T - 99.9T */
CHK_FORMAT(1024LL * 1024 * 1024 * 1024, 99.95, "%0.01f TB", double);
#undef CHK_FORMAT
/* 100T+ */
strcpy(tmp[cur], "infty");
return tmp[cur];
}
/* Describe time delta. Returns one static buffer, 34 chars of less. */
static u8 *DTD(u64 cur_ms, u64 event_ms)
{
static u8 tmp[64];
u64 delta;
s32 t_d, t_h, t_m, t_s;
if (!event_ms)
return "none seen yet";
delta = cur_ms - event_ms;
t_d = delta / 1000 / 60 / 60 / 24;
t_h = (delta / 1000 / 60 / 60) % 24;
t_m = (delta / 1000 / 60) % 60;
t_s = (delta / 1000) % 60;
sprintf(tmp, "%s days, %u hrs, %u min, %u sec", DI(t_d), t_h, t_m, t_s);
return tmp;
}
/* Mark deterministic checks as done for a particular queue entry. We use the
.state file to avoid repeating deterministic fuzzing when resuming aborted
scans. */
static void mark_as_det_done(struct queue_entry *q)
{
u8 *fn = strrchr(q->fname, '/');
s32 fd;
fn = alloc_printf("%s/queue/.state/deterministic_done/%s", out_dir, fn + 1);
fd = open(fn, O_WRONLY | O_CREAT | O_EXCL, 0600);
if (fd < 0)
PFATAL("Unable to create '%s'", fn);
close(fd);
ck_free(fn);
q->passed_det = 1;
}
/* Mark as variable. Create symlinks if possible to make it easier to examine
the files. */
static void mark_as_variable(struct queue_entry *q)
{
u8 *fn = strrchr(q->fname, '/') + 1, *ldest;
//创建符号链接out_dir/queue/.state/variable_behavior/fname
ldest = alloc_printf("../../%s", fn);
fn = alloc_printf("%s/queue/.state/variable_behavior/%s", out_dir, fn);
if (symlink(ldest, fn))
{
s32 fd = open(fn, O_WRONLY | O_CREAT | O_EXCL, 0600);
if (fd < 0)
PFATAL("Unable to create '%s'", fn);
close(fd);
}
ck_free(ldest);
ck_free(fn);
//设置queue的var_behavior为1
q->var_behavior = 1;
}
/* Mark / unmark as redundant (edge-only). This is not used for restoring state,
but may be useful for post-processing datasets. */
static void mark_as_redundant(struct queue_entry *q, u8 state)
{
u8 *fn;
s32 fd;
if (state == q->fs_redundant)
return;
q->fs_redundant = state;
fn = strrchr(q->fname, '/');
fn = alloc_printf("%s/queue/.state/redundant_edges/%s", out_dir, fn + 1);
//如果state为1
if (state)
{
//尝试创建out_dir/queue/.state/redundant_edges/fname
fd = open(fn, O_WRONLY | O_CREAT | O_EXCL, 0600);
if (fd < 0)
PFATAL("Unable to create '%s'", fn);
close(fd);
}
else
{
//尝试删除out_dir/queue/.state/redundant_edges/fname
if (unlink(fn))
PFATAL("Unable to remove '%s'", fn);
}
ck_free(fn);
}
/* Append new test case to the queue. 仅当一个测试样例触发了新的覆盖率/行为*/
//将新的测试用例插入队列，并初始化fname文件名称，增加cur_depth深度++
// queued_paths测试用例数量++，pending_not_fuzzed没被fuzzed测试用例数量++，更新last_path_time = get_cur_time()
static void add_to_queue(u8 *fname, u32 len, u8 passed_det)
{
//通过ck_alloc分配一个 queue_entry 结构体，并进行初始化
struct queue_entry *q = ck_alloc(sizeof(struct queue_entry));
q->fname = fname;
q->len = len;
q->depth = cur_depth + 1;
q->passed_det = passed_det;
if (q->depth > max_depth)
max_depth = q->depth;
if (queue_top)
{
queue_top->next = q;
queue_top = q;
}
else
q_prev100 = queue = queue_top = q;
queued_paths++; // queue计数器加1
pending_not_fuzzed++; // 待fuzz的样例计数器加1
cycles_wo_finds = 0;
if (!(queued_paths % 100))
{
q_prev100->next_100 = q;
q_prev100 = q;
}
last_path_time = get_cur_time();
}
/* Destroy the entire queue. */
EXP_ST void destroy_queue(void)
{
struct queue_entry *q = queue, *n;
while (q)
{
n = q->next;
ck_free(q->fname);
ck_free(q->trace_mini);
ck_free(q);
q = n;
}
}
/* Write bitmap to file. The bitmap is useful mostly for the secret
-B option, to focus a separate fuzzing session on a particular
interesting input without rediscovering all the others. */
EXP_ST void write_bitmap(void)
{
u8 *fname;
s32 fd;
if (!bitmap_changed)
return;
bitmap_changed = 0;
fname = alloc_printf("%s/fuzz_bitmap", out_dir);
fd = open(fname, O_WRONLY | O_CREAT | O_TRUNC, 0600);
if (fd < 0)
PFATAL("Unable to open '%s'", fname);
ck_write(fd, virgin_bits, MAP_SIZE, fname);
close(fd);
ck_free(fname);
}
/* Read bitmap from file. This is for the -B option again. */
EXP_ST void read_bitmap(u8 *fname)
{
s32 fd = open(fname, O_RDONLY);
if (fd < 0)
PFATAL("Unable to open '%s'", fname);
ck_read(fd, virgin_bits, MAP_SIZE, fname);
close(fd);
}
/* Check if the current execution path brings anything new to the table.
Update virgin bits to reflect the finds. Returns 1 if the only change is
the hit-count for a particular tuple; 2 if there are new tuples seen.
Updates the map, so subsequent calls will always return 0.
This function is called after every exec() on a fairly large buffer, so
it needs to be fast. We do this in 32-bit and 64-bit flavors. */
//判断测试用例是否产生新状态,检查有没有新路径或者某个路径的执行次数有所不同
static inline u8 has_new_bits(u8 *virgin_map)
{
//初始化current和virgin为trace_bits和virgin_map的u64首元素地址
#ifdef __x86_64__
u64 *current = (u64 *)trace_bits;
u64 *virgin = (u64 *)virgin_map;
u32 i = (MAP_SIZE >> 3);
#else
u32 *current = (u32 *)trace_bits;
u32 *virgin = (u32 *)virgin_map;
u32 i = (MAP_SIZE >> 2);
#endif /* ^__x86_64__ */
//设置ret的值为0
u8 ret = 0;
// 8个字节一组，每次从trace_bits(也就是共享内存)里取出8个字节
while (i--)
{
/* Optimize for (*current & *virgin) == 0 - i.e., no bits in current bitmap
that have not been already cleared from the virgin map - since this will
almost always be the case. */
//使用unlikely()说明执行else的可能性大 使用likely()说明执行if的可能性大，目的是提高系统的运行速度
//如果current不为0(表明当前路径已hit)，且*current & *virgin不为0，即代表current测试用例发现了新路径或者某条路径的执行次数和之前有所不同（即在virgin中未出现过）
if (unlikely(*current) && unlikely(*current & *virgin))
{
//如果ret当前小于2
if (likely(ret < 2))
{
//取current的首字节地址为cur，virgin的首字节地址为vir
u8 *cur = (u8 *)current;
u8 *vir = (u8 *)virgin;
/* Looks like we have not found any new bytes yet; see if any non-zero
bytes in current[] are pristine in virgin[]. */
// i的范围是0-7，比较cur[i] && vir[i] == 0xff，如果有一个为真，则设置ret为2
#ifdef __x86_64__
//64位中cur和vir的任何对应一位若都为FF 则返回2 否则返回1
//注意==的优先级比&&要高，所以先判断vir[i]是否是0xff，即之前从未被覆盖到，然后再和cur[i]进行逻辑与
if ((cur[0] && vir[0] == 0xff) || (cur[1] && vir[1] == 0xff) ||
(cur[2] && vir[2] == 0xff) || (cur[3] && vir[3] == 0xff) ||
(cur[4] && vir[4] == 0xff) || (cur[5] && vir[5] == 0xff) ||
(cur[6] && vir[6] == 0xff) || (cur[7] && vir[7] == 0xff))
ret = 2; //这代表发现了之前没有出现过的tuple
else
ret = 1; //这代表仅仅只是改变了某个tuple的hit-count
#else
//32位中cur和vir的前四对应位若为FF 则返回2 否则返回1
if ((cur[0] && vir[0] == 0xff) || (cur[1] && vir[1] == 0xff) ||
(cur[2] && vir[2] == 0xff) || (cur[3] && vir[3] == 0xff))
ret = 2;
else
ret = 1;
#endif /* ^__x86_64__ */
}
*virgin &= ~*current; //将表示当前执行情况的位在virgin位图中标出，下次在出现相同的执行情况时if语句将判断为false，即没有出现新的情况
}
// current和virgin移动到下一组8个字节，直到MAPSIZE全被遍历完
current++;
virgin++;
}
//如果传入给has_new_bits的参数virgin_map是virgin_bits,且ret不为0，就设置bitmap_changed为1
if (ret && virgin_map == virgin_bits)
bitmap_changed = 1;
return ret;
}
/* Count the number of bits set in the provided bitmap. Used for the status
screen several times every second, does not have to be fast. */