| /* |
| american fuzzy lop++ - forkserver code |
| -------------------------------------- |
| |
| Originally written by Michal Zalewski |
| |
| Forkserver design by Jann Horn <jannhorn@googlemail.com> |
| |
| Now maintained by Marc Heuse <mh@mh-sec.de>, |
| Heiko Eißfeldt <heiko.eissfeldt@hexco.de> and |
| Andrea Fioraldi <andreafioraldi@gmail.com> and |
| Dominik Maier <mail@dmnk.co> |
| |
| |
| 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 |
| |
| Shared code that implements a forkserver. This is used by the fuzzer |
| as well the other components like afl-tmin. |
| |
| */ |
| |
| #include "config.h" |
| #include "types.h" |
| #include "debug.h" |
| #include "common.h" |
| #include "list.h" |
| #include "forkserver.h" |
| #include "hash.h" |
| |
| #include <stdio.h> |
| #include <unistd.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <time.h> |
| #include <errno.h> |
| #include <signal.h> |
| #include <fcntl.h> |
| #include <sys/time.h> |
| #include <sys/wait.h> |
| #include <sys/resource.h> |
| #include <sys/select.h> |
| #include <sys/stat.h> |
| |
| /** |
| * The correct fds for reading and writing pipes |
| */ |
| |
| /* Describe integer as memory size. */ |
| |
| static list_t fsrv_list = {.element_prealloc_count = 0}; |
| |
| static void fsrv_exec_child(afl_forkserver_t *fsrv, char **argv) { |
| |
| if (fsrv->qemu_mode) setenv("AFL_DISABLE_LLVM_INSTRUMENTATION", "1", 0); |
| |
| execv(fsrv->target_path, argv); |
| |
| } |
| |
| /* Initializes the struct */ |
| |
| void afl_fsrv_init(afl_forkserver_t *fsrv) { |
| |
| // this structure needs default so we initialize it if this was not done |
| // already |
| fsrv->out_fd = -1; |
| fsrv->out_dir_fd = -1; |
| fsrv->dev_null_fd = -1; |
| fsrv->dev_urandom_fd = -1; |
| |
| /* Settings */ |
| fsrv->use_stdin = 1; |
| fsrv->no_unlink = 0; |
| fsrv->exec_tmout = EXEC_TIMEOUT; |
| fsrv->init_tmout = EXEC_TIMEOUT * FORK_WAIT_MULT; |
| fsrv->mem_limit = MEM_LIMIT; |
| fsrv->out_file = NULL; |
| |
| /* exec related stuff */ |
| fsrv->child_pid = -1; |
| fsrv->map_size = get_map_size(); |
| fsrv->use_fauxsrv = 0; |
| fsrv->last_run_timed_out = 0; |
| |
| fsrv->init_child_func = fsrv_exec_child; |
| |
| list_append(&fsrv_list, fsrv); |
| |
| } |
| |
| /* Initialize a new forkserver instance, duplicating "global" settings */ |
| void afl_fsrv_init_dup(afl_forkserver_t *fsrv_to, afl_forkserver_t *from) { |
| |
| fsrv_to->use_stdin = from->use_stdin; |
| fsrv_to->dev_null_fd = from->dev_null_fd; |
| fsrv_to->exec_tmout = from->exec_tmout; |
| fsrv_to->init_tmout = from->init_tmout; |
| fsrv_to->mem_limit = from->mem_limit; |
| fsrv_to->map_size = from->map_size; |
| fsrv_to->support_shmem_fuzz = from->support_shmem_fuzz; |
| fsrv_to->out_file = from->out_file; |
| fsrv_to->dev_urandom_fd = from->dev_urandom_fd; |
| fsrv_to->out_fd = from->out_fd; // not sure this is a good idea |
| fsrv_to->no_unlink = from->no_unlink; |
| |
| // These are forkserver specific. |
| fsrv_to->out_dir_fd = -1; |
| fsrv_to->child_pid = -1; |
| fsrv_to->use_fauxsrv = 0; |
| fsrv_to->last_run_timed_out = 0; |
| |
| fsrv_to->init_child_func = fsrv_exec_child; |
| // Note: do not copy ->add_extra_func |
| |
| list_append(&fsrv_list, fsrv_to); |
| |
| } |
| |
| /* Wrapper for select() and read(), reading a 32 bit var. |
| Returns the time passed to read. |
| If the wait times out, returns timeout_ms + 1; |
| Returns 0 if an error occurred (fd closed, signal, ...); */ |
| static u32 __attribute__((hot)) |
| read_s32_timed(s32 fd, s32 *buf, u32 timeout_ms, volatile u8 *stop_soon_p) { |
| |
| fd_set readfds; |
| FD_ZERO(&readfds); |
| FD_SET(fd, &readfds); |
| struct timeval timeout; |
| int sret; |
| ssize_t len_read; |
| |
| timeout.tv_sec = (timeout_ms / 1000); |
| timeout.tv_usec = (timeout_ms % 1000) * 1000; |
| #if !defined(__linux__) |
| u32 read_start = get_cur_time_us(); |
| #endif |
| |
| /* set exceptfds as well to return when a child exited/closed the pipe. */ |
| restart_select: |
| sret = select(fd + 1, &readfds, NULL, NULL, &timeout); |
| |
| if (likely(sret > 0)) { |
| |
| restart_read: |
| if (*stop_soon_p) { |
| |
| // Early return - the user wants to quit. |
| return 0; |
| |
| } |
| |
| len_read = read(fd, (u8 *)buf, 4); |
| |
| if (likely(len_read == 4)) { // for speed we put this first |
| |
| #if defined(__linux__) |
| u32 exec_ms = MIN( |
| timeout_ms, |
| ((u64)timeout_ms - (timeout.tv_sec * 1000 + timeout.tv_usec / 1000))); |
| #else |
| u32 exec_ms = MIN(timeout_ms, (get_cur_time_us() - read_start) / 1000); |
| #endif |
| |
| // ensure to report 1 ms has passed (0 is an error) |
| return exec_ms > 0 ? exec_ms : 1; |
| |
| } else if (unlikely(len_read == -1 && errno == EINTR)) { |
| |
| goto restart_read; |
| |
| } else if (unlikely(len_read < 4)) { |
| |
| return 0; |
| |
| } |
| |
| } else if (unlikely(!sret)) { |
| |
| *buf = -1; |
| return timeout_ms + 1; |
| |
| } else if (unlikely(sret < 0)) { |
| |
| if (likely(errno == EINTR)) goto restart_select; |
| |
| *buf = -1; |
| return 0; |
| |
| } |
| |
| return 0; // not reached |
| |
| } |
| |
| /* Internal forkserver for non_instrumented_mode=1 and non-forkserver mode runs. |
| It execvs for each fork, forwarding exit codes and child pids to afl. */ |
| |
| static void afl_fauxsrv_execv(afl_forkserver_t *fsrv, char **argv) { |
| |
| unsigned char tmp[4] = {0, 0, 0, 0}; |
| pid_t child_pid = -1; |
| |
| if (!be_quiet) { ACTF("Using Fauxserver:"); } |
| |
| /* Phone home and tell the parent that we're OK. If parent isn't there, |
| assume we're not running in forkserver mode and just execute program. */ |
| |
| if (write(FORKSRV_FD + 1, tmp, 4) != 4) { |
| |
| abort(); // TODO: Abort? |
| |
| } |
| |
| void (*old_sigchld_handler)(int) = signal(SIGCHLD, SIG_DFL); |
| |
| while (1) { |
| |
| uint32_t was_killed; |
| int status; |
| |
| /* Wait for parent by reading from the pipe. Exit if read fails. */ |
| |
| if (read(FORKSRV_FD, &was_killed, 4) != 4) { exit(0); } |
| |
| /* Create a clone of our process. */ |
| |
| child_pid = fork(); |
| |
| if (child_pid < 0) { PFATAL("Fork failed"); } |
| |
| /* In child process: close fds, resume execution. */ |
| |
| if (!child_pid) { // New child |
| |
| close(fsrv->out_dir_fd); |
| close(fsrv->dev_null_fd); |
| close(fsrv->dev_urandom_fd); |
| |
| if (fsrv->plot_file != NULL) { |
| |
| fclose(fsrv->plot_file); |
| fsrv->plot_file = NULL; |
| |
| } |
| |
| // enable terminating on sigpipe in the childs |
| struct sigaction sa; |
| memset((char *)&sa, 0, sizeof(sa)); |
| sa.sa_handler = SIG_DFL; |
| sigaction(SIGPIPE, &sa, NULL); |
| |
| signal(SIGCHLD, old_sigchld_handler); |
| // FORKSRV_FD is for communication with AFL, we don't need it in the |
| // child. |
| close(FORKSRV_FD); |
| close(FORKSRV_FD + 1); |
| |
| // TODO: exec... |
| |
| execv(fsrv->target_path, argv); |
| |
| /* Use a distinctive bitmap signature to tell the parent about execv() |
| falling through. */ |
| |
| *(u32 *)fsrv->trace_bits = EXEC_FAIL_SIG; |
| |
| PFATAL("Execv failed in fauxserver."); |
| |
| } |
| |
| /* In parent process: write PID to AFL. */ |
| |
| if (write(FORKSRV_FD + 1, &child_pid, 4) != 4) { exit(0); } |
| |
| /* after child exited, get and relay exit status to parent through waitpid. |
| */ |
| |
| if (waitpid(child_pid, &status, 0) < 0) { |
| |
| // Zombie Child could not be collected. Scary! |
| PFATAL("Fauxserver could not determin child's exit code. "); |
| |
| } |
| |
| /* Relay wait status to AFL pipe, then loop back. */ |
| |
| if (write(FORKSRV_FD + 1, &status, 4) != 4) { exit(0); } |
| |
| } |
| |
| } |
| |
| /* Report on the error received via the forkserver controller and exit */ |
| static void report_error_and_exit(int error) { |
| |
| switch (error) { |
| |
| case FS_ERROR_MAP_SIZE: |
| FATAL( |
| "AFL_MAP_SIZE is not set and fuzzing target reports that the " |
| "required size is very large. Solution: Run the fuzzing target " |
| "stand-alone with the environment variable AFL_DEBUG=1 set and set " |
| "the value for __afl_final_loc in the AFL_MAP_SIZE environment " |
| "variable for afl-fuzz."); |
| break; |
| case FS_ERROR_MAP_ADDR: |
| FATAL( |
| "the fuzzing target reports that hardcoded map address might be the " |
| "reason the mmap of the shared memory failed. Solution: recompile " |
| "the target with either afl-clang-lto and do not set " |
| "AFL_LLVM_MAP_ADDR or recompile with afl-clang-fast."); |
| break; |
| case FS_ERROR_SHM_OPEN: |
| FATAL("the fuzzing target reports that the shm_open() call failed."); |
| break; |
| case FS_ERROR_SHMAT: |
| FATAL("the fuzzing target reports that the shmat() call failed."); |
| break; |
| case FS_ERROR_MMAP: |
| FATAL( |
| "the fuzzing target reports that the mmap() call to the shared " |
| "memory failed."); |
| break; |
| default: |
| FATAL("unknown error code %u from fuzzing target!", error); |
| |
| } |
| |
| } |
| |
| /* Spins up fork server. The idea is explained here: |
| |
| http://lcamtuf.blogspot.com/2014/10/fuzzing-binaries-without-execve.html |
| |
| In essence, the instrumentation allows us to skip execve(), and just keep |
| cloning a stopped child. So, we just execute once, and then send commands |
| through a pipe. The other part of this logic is in afl-as.h / llvm_mode */ |
| |
| void afl_fsrv_start(afl_forkserver_t *fsrv, char **argv, |
| volatile u8 *stop_soon_p, u8 debug_child_output) { |
| |
| int st_pipe[2], ctl_pipe[2]; |
| s32 status; |
| s32 rlen; |
| |
| if (!be_quiet) { ACTF("Spinning up the fork server..."); } |
| |
| if (fsrv->use_fauxsrv) { |
| |
| /* TODO: Come up with sone nice way to initialize this all */ |
| |
| if (fsrv->init_child_func != fsrv_exec_child) { |
| |
| FATAL("Different forkserver not compatible with fauxserver"); |
| |
| } |
| |
| fsrv->init_child_func = afl_fauxsrv_execv; |
| |
| } |
| |
| if (pipe(st_pipe) || pipe(ctl_pipe)) { PFATAL("pipe() failed"); } |
| |
| fsrv->last_run_timed_out = 0; |
| fsrv->fsrv_pid = fork(); |
| |
| if (fsrv->fsrv_pid < 0) { PFATAL("fork() failed"); } |
| |
| if (!fsrv->fsrv_pid) { |
| |
| /* CHILD PROCESS */ |
| |
| // enable terminating on sigpipe in the childs |
| struct sigaction sa; |
| memset((char *)&sa, 0, sizeof(sa)); |
| sa.sa_handler = SIG_DFL; |
| sigaction(SIGPIPE, &sa, NULL); |
| |
| struct rlimit r; |
| |
| /* Umpf. On OpenBSD, the default fd limit for root users is set to |
| soft 128. Let's try to fix that... */ |
| if (!getrlimit(RLIMIT_NOFILE, &r) && r.rlim_cur < FORKSRV_FD + 2) { |
| |
| r.rlim_cur = FORKSRV_FD + 2; |
| setrlimit(RLIMIT_NOFILE, &r); /* Ignore errors */ |
| |
| } |
| |
| if (fsrv->mem_limit) { |
| |
| r.rlim_max = r.rlim_cur = ((rlim_t)fsrv->mem_limit) << 20; |
| |
| #ifdef RLIMIT_AS |
| setrlimit(RLIMIT_AS, &r); /* Ignore errors */ |
| #else |
| /* This takes care of OpenBSD, which doesn't have RLIMIT_AS, but |
| according to reliable sources, RLIMIT_DATA covers anonymous |
| maps - so we should be getting good protection against OOM bugs. */ |
| |
| setrlimit(RLIMIT_DATA, &r); /* Ignore errors */ |
| #endif /* ^RLIMIT_AS */ |
| |
| } |
| |
| /* Dumping cores is slow and can lead to anomalies if SIGKILL is delivered |
| before the dump is complete. */ |
| |
| // r.rlim_max = r.rlim_cur = 0; |
| // setrlimit(RLIMIT_CORE, &r); /* Ignore errors */ |
| |
| /* Isolate the process and configure standard descriptors. If out_file is |
| specified, stdin is /dev/null; otherwise, out_fd is cloned instead. */ |
| |
| setsid(); |
| |
| if (!(debug_child_output)) { |
| |
| dup2(fsrv->dev_null_fd, 1); |
| dup2(fsrv->dev_null_fd, 2); |
| |
| } |
| |
| if (!fsrv->use_stdin) { |
| |
| dup2(fsrv->dev_null_fd, 0); |
| |
| } else { |
| |
| dup2(fsrv->out_fd, 0); |
| close(fsrv->out_fd); |
| |
| } |
| |
| /* Set up control and status pipes, close the unneeded original fds. */ |
| |
| if (dup2(ctl_pipe[0], FORKSRV_FD) < 0) { PFATAL("dup2() failed"); } |
| if (dup2(st_pipe[1], FORKSRV_FD + 1) < 0) { PFATAL("dup2() failed"); } |
| |
| close(ctl_pipe[0]); |
| close(ctl_pipe[1]); |
| close(st_pipe[0]); |
| close(st_pipe[1]); |
| |
| close(fsrv->out_dir_fd); |
| close(fsrv->dev_null_fd); |
| close(fsrv->dev_urandom_fd); |
| |
| if (fsrv->plot_file != NULL) { |
| |
| fclose(fsrv->plot_file); |
| fsrv->plot_file = NULL; |
| |
| } |
| |
| /* This should improve performance a bit, since it stops the linker from |
| doing extra work post-fork(). */ |
| |
| if (!getenv("LD_BIND_LAZY")) { setenv("LD_BIND_NOW", "1", 0); } |
| |
| /* Set sane defaults for ASAN if nothing else specified. */ |
| |
| setenv("ASAN_OPTIONS", |
| "abort_on_error=1:" |
| "detect_leaks=0:" |
| "malloc_context_size=0:" |
| "symbolize=0:" |
| "allocator_may_return_null=1:" |
| "handle_segv=0:" |
| "handle_sigbus=0:" |
| "handle_abort=0:" |
| "handle_sigfpe=0:" |
| "handle_sigill=0", |
| 0); |
| |
| /* Set sane defaults for UBSAN if nothing else specified. */ |
| |
| setenv("UBSAN_OPTIONS", |
| "halt_on_error=1:" |
| "abort_on_error=1:" |
| "malloc_context_size=0:" |
| "allocator_may_return_null=1:" |
| "symbolize=0:" |
| "handle_segv=0:" |
| "handle_sigbus=0:" |
| "handle_abort=0:" |
| "handle_sigfpe=0:" |
| "handle_sigill=0", |
| 0); |
| |
| /* MSAN is tricky, because it doesn't support abort_on_error=1 at this |
| point. So, we do this in a very hacky way. */ |
| |
| setenv("MSAN_OPTIONS", |
| "exit_code=" STRINGIFY(MSAN_ERROR) ":" |
| "symbolize=0:" |
| "abort_on_error=1:" |
| "malloc_context_size=0:" |
| "allocator_may_return_null=1:" |
| "msan_track_origins=0:" |
| "handle_segv=0:" |
| "handle_sigbus=0:" |
| "handle_abort=0:" |
| "handle_sigfpe=0:" |
| "handle_sigill=0", |
| 0); |
| |
| fsrv->init_child_func(fsrv, argv); |
| |
| /* Use a distinctive bitmap signature to tell the parent about execv() |
| falling through. */ |
| |
| *(u32 *)fsrv->trace_bits = EXEC_FAIL_SIG; |
| fprintf(stderr, "Error: execv to target failed\n"); |
| exit(0); |
| |
| } |
| |
| /* PARENT PROCESS */ |
| |
| char pid_buf[16]; |
| sprintf(pid_buf, "%d", fsrv->fsrv_pid); |
| if (fsrv->cmplog_binary) |
| setenv("__AFL_TARGET_PID2", pid_buf, 1); |
| else |
| setenv("__AFL_TARGET_PID1", pid_buf, 1); |
| |
| /* Close the unneeded endpoints. */ |
| |
| close(ctl_pipe[0]); |
| close(st_pipe[1]); |
| |
| fsrv->fsrv_ctl_fd = ctl_pipe[1]; |
| fsrv->fsrv_st_fd = st_pipe[0]; |
| |
| /* Wait for the fork server to come up, but don't wait too long. */ |
| |
| rlen = 0; |
| if (fsrv->exec_tmout) { |
| |
| u32 time_ms = read_s32_timed(fsrv->fsrv_st_fd, &status, fsrv->init_tmout, |
| stop_soon_p); |
| |
| if (!time_ms) { |
| |
| kill(fsrv->fsrv_pid, SIGKILL); |
| |
| } else if (time_ms > fsrv->init_tmout) { |
| |
| fsrv->last_run_timed_out = 1; |
| kill(fsrv->fsrv_pid, SIGKILL); |
| |
| } else { |
| |
| rlen = 4; |
| |
| } |
| |
| } else { |
| |
| rlen = read(fsrv->fsrv_st_fd, &status, 4); |
| |
| } |
| |
| /* If we have a four-byte "hello" message from the server, we're all set. |
| Otherwise, try to figure out what went wrong. */ |
| |
| if (rlen == 4) { |
| |
| if (!be_quiet) { OKF("All right - fork server is up."); } |
| |
| if (getenv("AFL_DEBUG")) { |
| |
| ACTF("Extended forkserver functions received (%08x).", status); |
| |
| } |
| |
| if ((status & FS_OPT_ERROR) == FS_OPT_ERROR) |
| report_error_and_exit(FS_OPT_GET_ERROR(status)); |
| |
| if ((status & FS_OPT_ENABLED) == FS_OPT_ENABLED) { |
| |
| // workaround for recent afl++ versions |
| if ((status & FS_OPT_OLD_AFLPP_WORKAROUND) == FS_OPT_OLD_AFLPP_WORKAROUND) |
| status = (status & 0xf0ffffff); |
| |
| if ((status & FS_OPT_SNAPSHOT) == FS_OPT_SNAPSHOT) { |
| |
| fsrv->snapshot = 1; |
| if (!be_quiet) { ACTF("Using SNAPSHOT feature."); } |
| |
| } |
| |
| if ((status & FS_OPT_SHDMEM_FUZZ) == FS_OPT_SHDMEM_FUZZ) { |
| |
| if (fsrv->support_shmem_fuzz) { |
| |
| fsrv->use_shmem_fuzz = 1; |
| if (!be_quiet) { ACTF("Using SHARED MEMORY FUZZING feature."); } |
| |
| if ((status & FS_OPT_AUTODICT) == 0) { |
| |
| u32 send_status = (FS_OPT_ENABLED | FS_OPT_SHDMEM_FUZZ); |
| if (write(fsrv->fsrv_ctl_fd, &send_status, 4) != 4) { |
| |
| FATAL("Writing to forkserver failed."); |
| |
| } |
| |
| } |
| |
| } else { |
| |
| FATAL( |
| "Target requested sharedmem fuzzing, but we failed to enable " |
| "it."); |
| |
| } |
| |
| } |
| |
| if ((status & FS_OPT_MAPSIZE) == FS_OPT_MAPSIZE) { |
| |
| u32 tmp_map_size = FS_OPT_GET_MAPSIZE(status); |
| |
| if (!fsrv->map_size) { fsrv->map_size = MAP_SIZE; } |
| |
| if (unlikely(tmp_map_size % 8)) { |
| |
| // should not happen |
| WARNF("Target reported non-aligned map size of %u", tmp_map_size); |
| tmp_map_size = (((tmp_map_size + 8) >> 3) << 3); |
| |
| } |
| |
| if (!be_quiet) { ACTF("Target map size: %u", tmp_map_size); } |
| if (tmp_map_size > fsrv->map_size) { |
| |
| FATAL( |
| "Target's coverage map size of %u is larger than the one this " |
| "afl++ is set with (%u). Either set AFL_MAP_SIZE=%u and restart " |
| " afl-fuzz, or change MAP_SIZE_POW2 in config.h and recompile " |
| "afl-fuzz", |
| tmp_map_size, fsrv->map_size, tmp_map_size); |
| |
| } |
| |
| fsrv->map_size = tmp_map_size; |
| |
| } |
| |
| if ((status & FS_OPT_AUTODICT) == FS_OPT_AUTODICT) { |
| |
| if (fsrv->add_extra_func == NULL || fsrv->afl_ptr == NULL) { |
| |
| // this is not afl-fuzz - or it is cmplog - we deny and return |
| if (fsrv->use_shmem_fuzz) { |
| |
| status = (FS_OPT_ENABLED | FS_OPT_SHDMEM_FUZZ); |
| |
| } else { |
| |
| status = (FS_OPT_ENABLED); |
| |
| } |
| |
| if (write(fsrv->fsrv_ctl_fd, &status, 4) != 4) { |
| |
| FATAL("Writing to forkserver failed."); |
| |
| } |
| |
| return; |
| |
| } |
| |
| if (!be_quiet) { ACTF("Using AUTODICT feature."); } |
| |
| if (fsrv->use_shmem_fuzz) { |
| |
| status = (FS_OPT_ENABLED | FS_OPT_AUTODICT | FS_OPT_SHDMEM_FUZZ); |
| |
| } else { |
| |
| status = (FS_OPT_ENABLED | FS_OPT_AUTODICT); |
| |
| } |
| |
| if (write(fsrv->fsrv_ctl_fd, &status, 4) != 4) { |
| |
| FATAL("Writing to forkserver failed."); |
| |
| } |
| |
| if (read(fsrv->fsrv_st_fd, &status, 4) != 4) { |
| |
| FATAL("Reading from forkserver failed."); |
| |
| } |
| |
| if (status < 2 || (u32)status > 0xffffff) { |
| |
| FATAL("Dictionary has an illegal size: %d", status); |
| |
| } |
| |
| u32 offset = 0, count = 0; |
| u32 len = status; |
| u8 *dict = ck_alloc(len); |
| if (dict == NULL) { |
| |
| FATAL("Could not allocate %u bytes of autodictionary memory", len); |
| |
| } |
| |
| while (len != 0) { |
| |
| rlen = read(fsrv->fsrv_st_fd, dict + offset, len); |
| if (rlen > 0) { |
| |
| len -= rlen; |
| offset += rlen; |
| |
| } else { |
| |
| FATAL( |
| "Reading autodictionary fail at position %u with %u bytes " |
| "left.", |
| offset, len); |
| |
| } |
| |
| } |
| |
| offset = 0; |
| while (offset < (u32)status && |
| (u8)dict[offset] + offset < (u32)status) { |
| |
| fsrv->add_extra_func(fsrv->afl_ptr, dict + offset + 1, |
| (u8)dict[offset]); |
| offset += (1 + dict[offset]); |
| count++; |
| |
| } |
| |
| if (!be_quiet) { ACTF("Loaded %u autodictionary entries", count); } |
| ck_free(dict); |
| |
| } |
| |
| } |
| |
| return; |
| |
| } |
| |
| if (fsrv->last_run_timed_out) { |
| |
| FATAL("Timeout while initializing fork server (adjusting -t may help)"); |
| |
| } |
| |
| if (waitpid(fsrv->fsrv_pid, &status, 0) <= 0) { PFATAL("waitpid() failed"); } |
| |
| if (WIFSIGNALED(status)) { |
| |
| if (fsrv->mem_limit && fsrv->mem_limit < 500 && fsrv->uses_asan) { |
| |
| SAYF("\n" cLRD "[-] " cRST |
| "Whoops, the target binary crashed suddenly, " |
| "before receiving any input\n" |
| " from the fuzzer! Since it seems to be built with ASAN and you " |
| "have a\n" |
| " restrictive memory limit configured, this is expected; please " |
| "read\n" |
| " %s/notes_for_asan.md for help.\n", |
| doc_path); |
| |
| } else if (!fsrv->mem_limit) { |
| |
| SAYF("\n" cLRD "[-] " cRST |
| "Whoops, the target binary crashed suddenly, " |
| "before receiving any input\n" |
| " from the fuzzer! There are several probable explanations:\n\n" |
| |
| " - The binary is just buggy and explodes entirely on its own. " |
| "If so, you\n" |
| " need to fix the underlying problem or find a better " |
| "replacement.\n\n" |
| |
| MSG_FORK_ON_APPLE |
| |
| " - Less likely, there is a horrible bug in the fuzzer. If other " |
| "options\n" |
| " fail, poke <afl-users@googlegroups.com> for troubleshooting " |
| "tips.\n"); |
| |
| } else { |
| |
| u8 val_buf[STRINGIFY_VAL_SIZE_MAX]; |
| |
| SAYF("\n" cLRD "[-] " cRST |
| "Whoops, the target binary crashed suddenly, " |
| "before receiving any input\n" |
| " from the fuzzer! There are several probable explanations:\n\n" |
| |
| " - The current memory limit (%s) is too restrictive, causing " |
| "the\n" |
| " target to hit an OOM condition in the dynamic linker. Try " |
| "bumping up\n" |
| " the limit with the -m setting in the command line. A simple " |
| "way confirm\n" |
| " this diagnosis would be:\n\n" |
| |
| MSG_ULIMIT_USAGE |
| " /path/to/fuzzed_app )\n\n" |
| |
| " Tip: you can use http://jwilk.net/software/recidivm to " |
| "quickly\n" |
| " estimate the required amount of virtual memory for the " |
| "binary.\n\n" |
| |
| " - The binary is just buggy and explodes entirely on its own. " |
| "If so, you\n" |
| " need to fix the underlying problem or find a better " |
| "replacement.\n\n" |
| |
| MSG_FORK_ON_APPLE |
| |
| " - Less likely, there is a horrible bug in the fuzzer. If other " |
| "options\n" |
| " fail, poke <afl-users@googlegroups.com> for troubleshooting " |
| "tips.\n", |
| stringify_mem_size(val_buf, sizeof(val_buf), fsrv->mem_limit << 20), |
| fsrv->mem_limit - 1); |
| |
| } |
| |
| FATAL("Fork server crashed with signal %d", WTERMSIG(status)); |
| |
| } |
| |
| if (*(u32 *)fsrv->trace_bits == EXEC_FAIL_SIG) { |
| |
| FATAL("Unable to execute target application ('%s')", argv[0]); |
| |
| } |
| |
| if (fsrv->mem_limit && fsrv->mem_limit < 500 && fsrv->uses_asan) { |
| |
| SAYF("\n" cLRD "[-] " cRST |
| "Hmm, looks like the target binary terminated " |
| "before we could complete a\n" |
| " handshake with the injected code. Since it seems to be built " |
| "with ASAN and\n" |
| " you have a restrictive memory limit configured, this is " |
| "expected; please\n" |
| " read %s/notes_for_asan.md for help.\n", |
| doc_path); |
| |
| } else if (!fsrv->mem_limit) { |
| |
| SAYF("\n" cLRD "[-] " cRST |
| "Hmm, looks like the target binary terminated before we could" |
| " complete a handshake with the injected code.\n" |
| "If the target was compiled with afl-clang-lto and AFL_LLVM_MAP_ADDR" |
| " then recompiling without this parameter.\n" |
| "Otherwise there is a horrible bug in the fuzzer.\n" |
| "Poke <afl-users@googlegroups.com> for troubleshooting tips.\n"); |
| |
| } else { |
| |
| u8 val_buf[STRINGIFY_VAL_SIZE_MAX]; |
| |
| SAYF( |
| "\n" cLRD "[-] " cRST |
| "Hmm, looks like the target binary terminated " |
| "before we could complete a\n" |
| " handshake with the injected code. There are %s probable " |
| "explanations:\n\n" |
| |
| "%s" |
| " - The current memory limit (%s) is too restrictive, causing an " |
| "OOM\n" |
| " fault in the dynamic linker. This can be fixed with the -m " |
| "option. A\n" |
| " simple way to confirm the diagnosis may be:\n\n" |
| |
| MSG_ULIMIT_USAGE |
| " /path/to/fuzzed_app )\n\n" |
| |
| " Tip: you can use http://jwilk.net/software/recidivm to quickly\n" |
| " estimate the required amount of virtual memory for the " |
| "binary.\n\n" |
| |
| " - the target was compiled with afl-clang-lto and a constructor " |
| "was\n" |
| " instrumented, recompiling without AFL_LLVM_MAP_ADDR might solve " |
| "your \n" |
| " problem\n\n" |
| |
| " - Less likely, there is a horrible bug in the fuzzer. If other " |
| "options\n" |
| " fail, poke <afl-users@googlegroups.com> for troubleshooting " |
| "tips.\n", |
| getenv(DEFER_ENV_VAR) ? "three" : "two", |
| getenv(DEFER_ENV_VAR) |
| ? " - You are using deferred forkserver, but __AFL_INIT() is " |
| "never\n" |
| " reached before the program terminates.\n\n" |
| : "", |
| stringify_int(val_buf, sizeof(val_buf), fsrv->mem_limit << 20), |
| fsrv->mem_limit - 1); |
| |
| } |
| |
| FATAL("Fork server handshake failed"); |
| |
| } |
| |
| static void afl_fsrv_kill(afl_forkserver_t *fsrv) { |
| |
| if (fsrv->child_pid > 0) { kill(fsrv->child_pid, SIGKILL); } |
| if (fsrv->fsrv_pid > 0) { |
| |
| kill(fsrv->fsrv_pid, SIGKILL); |
| if (waitpid(fsrv->fsrv_pid, NULL, 0) <= 0) { WARNF("error waitpid\n"); } |
| |
| } |
| |
| } |
| |
| /* Delete the current testcase and write the buf to the testcase file */ |
| |
| void afl_fsrv_write_to_testcase(afl_forkserver_t *fsrv, u8 *buf, size_t len) { |
| |
| if (fsrv->shmem_fuzz) { |
| |
| *fsrv->shmem_fuzz_len = len; |
| memcpy(fsrv->shmem_fuzz, buf, len); |
| #ifdef _DEBUG |
| if (getenv("AFL_DEBUG")) { |
| |
| fprintf(stderr, "FS crc: %016llx len: %u\n", |
| hash64(fsrv->shmem_fuzz, *fsrv->shmem_fuzz_len, 0xa5b35705), |
| *fsrv->shmem_fuzz_len); |
| fprintf(stderr, "SHM :"); |
| for (int i = 0; i < *fsrv->shmem_fuzz_len; i++) |
| fprintf(stderr, "%02x", fsrv->shmem_fuzz[i]); |
| fprintf(stderr, "\nORIG:"); |
| for (int i = 0; i < *fsrv->shmem_fuzz_len; i++) |
| fprintf(stderr, "%02x", buf[i]); |
| fprintf(stderr, "\n"); |
| |
| } |
| |
| #endif |
| |
| } else { |
| |
| s32 fd = fsrv->out_fd; |
| |
| if (!fsrv->use_stdin && fsrv->out_file) { |
| |
| if (unlikely(fsrv->no_unlink)) { |
| |
| fd = open(fsrv->out_file, O_WRONLY | O_CREAT | O_TRUNC, 0600); |
| |
| } else { |
| |
| unlink(fsrv->out_file); /* Ignore errors. */ |
| fd = open(fsrv->out_file, O_WRONLY | O_CREAT | O_EXCL, 0600); |
| |
| } |
| |
| if (fd < 0) { PFATAL("Unable to create '%s'", fsrv->out_file); } |
| |
| } else if (unlikely(fd <= 0)) { |
| |
| // We should have a (non-stdin) fd at this point, else we got a problem. |
| FATAL( |
| "Nowhere to write output to (neither out_fd nor out_file set (fd is " |
| "%d))", |
| fd); |
| |
| } else { |
| |
| lseek(fd, 0, SEEK_SET); |
| |
| } |
| |
| ck_write(fd, buf, len, fsrv->out_file); |
| |
| if (fsrv->use_stdin) { |
| |
| if (ftruncate(fd, len)) { PFATAL("ftruncate() failed"); } |
| lseek(fd, 0, SEEK_SET); |
| |
| } else { |
| |
| close(fd); |
| |
| } |
| |
| } |
| |
| } |
| |
| /* Execute target application, monitoring for timeouts. Return status |
| information. The called program will update afl->fsrv->trace_bits. */ |
| |
| fsrv_run_result_t afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 timeout, |
| volatile u8 *stop_soon_p) { |
| |
| s32 res; |
| u32 exec_ms; |
| u32 write_value = fsrv->last_run_timed_out; |
| |
| /* After this memset, fsrv->trace_bits[] are effectively volatile, so we |
| must prevent any earlier operations from venturing into that |
| territory. */ |
| |
| memset(fsrv->trace_bits, 0, fsrv->map_size); |
| |
| MEM_BARRIER(); |
| |
| /* we have the fork server (or faux server) up and running |
| First, tell it if the previous run timed out. */ |
| |
| if ((res = write(fsrv->fsrv_ctl_fd, &write_value, 4)) != 4) { |
| |
| if (*stop_soon_p) { return 0; } |
| RPFATAL(res, "Unable to request new process from fork server (OOM?)"); |
| |
| } |
| |
| fsrv->last_run_timed_out = 0; |
| |
| if ((res = read(fsrv->fsrv_st_fd, &fsrv->child_pid, 4)) != 4) { |
| |
| if (*stop_soon_p) { return 0; } |
| RPFATAL(res, "Unable to request new process from fork server (OOM?)"); |
| |
| } |
| |
| if (fsrv->child_pid <= 0) { |
| |
| if (*stop_soon_p) { return 0; } |
| FATAL("Fork server is misbehaving (OOM?)"); |
| |
| } |
| |
| exec_ms = read_s32_timed(fsrv->fsrv_st_fd, &fsrv->child_status, timeout, |
| stop_soon_p); |
| |
| if (exec_ms > timeout) { |
| |
| /* If there was no response from forkserver after timeout seconds, |
| we kill the child. The forkserver should inform us afterwards */ |
| |
| kill(fsrv->child_pid, SIGKILL); |
| fsrv->last_run_timed_out = 1; |
| if (read(fsrv->fsrv_st_fd, &fsrv->child_status, 4) < 4) { exec_ms = 0; } |
| |
| } |
| |
| if (!exec_ms) { |
| |
| if (*stop_soon_p) { return 0; } |
| SAYF("\n" cLRD "[-] " cRST |
| "Unable to communicate with fork server. Some possible reasons:\n\n" |
| " - You've run out of memory. Use -m to increase the the memory " |
| "limit\n" |
| " to something higher than %lld.\n" |
| " - The binary or one of the libraries it uses manages to " |
| "create\n" |
| " threads before the forkserver initializes.\n" |
| " - The binary, at least in some circumstances, exits in a way " |
| "that\n" |
| " also kills the parent process - raise() could be the " |
| "culprit.\n" |
| " - If using persistent mode with QEMU, " |
| "AFL_QEMU_PERSISTENT_ADDR " |
| "is\n" |
| " probably not valid (hint: add the base address in case of " |
| "PIE)" |
| "\n\n" |
| "If all else fails you can disable the fork server via " |
| "AFL_NO_FORKSRV=1.\n", |
| fsrv->mem_limit); |
| RPFATAL(res, "Unable to communicate with fork server"); |
| |
| } |
| |
| if (!WIFSTOPPED(fsrv->child_status)) { fsrv->child_pid = 0; } |
| |
| fsrv->total_execs++; |
| |
| /* Any subsequent operations on fsrv->trace_bits must not be moved by the |
| compiler below this point. Past this location, fsrv->trace_bits[] |
| behave very normally and do not have to be treated as volatile. */ |
| |
| MEM_BARRIER(); |
| |
| /* Report outcome to caller. */ |
| |
| if (WIFSIGNALED(fsrv->child_status) && !*stop_soon_p) { |
| |
| fsrv->last_kill_signal = WTERMSIG(fsrv->child_status); |
| |
| if (fsrv->last_run_timed_out && fsrv->last_kill_signal == SIGKILL) { |
| |
| return FSRV_RUN_TMOUT; |
| |
| } |
| |
| return FSRV_RUN_CRASH; |
| |
| } |
| |
| /* A somewhat nasty hack for MSAN, which doesn't support abort_on_error and |
| must use a special exit code. */ |
| |
| if (fsrv->uses_asan && WEXITSTATUS(fsrv->child_status) == MSAN_ERROR) { |
| |
| fsrv->last_kill_signal = 0; |
| return FSRV_RUN_CRASH; |
| |
| } |
| |
| // Fauxserver should handle this now. |
| // if (tb4 == EXEC_FAIL_SIG) return FSRV_RUN_ERROR; |
| |
| return FSRV_RUN_OK; |
| |
| } |
| |
| void afl_fsrv_killall() { |
| |
| LIST_FOREACH(&fsrv_list, afl_forkserver_t, { |
| |
| afl_fsrv_kill(el); |
| |
| }); |
| |
| } |
| |
| void afl_fsrv_deinit(afl_forkserver_t *fsrv) { |
| |
| afl_fsrv_kill(fsrv); |
| list_remove(&fsrv_list, fsrv); |
| |
| } |
| |
