From c6e038fe25789caa8da777f53154de1bd7b4e178 Mon Sep 17 00:00:00 2001 From: hexcoder- Date: Mon, 4 Jan 2021 20:40:53 +0100 Subject: code cleanups (shadowed vars, (un)signed type mismatches, format types, etc.) --- src/afl-forkserver.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/afl-forkserver.c') diff --git a/src/afl-forkserver.c b/src/afl-forkserver.c index 90fa55e9..d6195cb5 100644 --- a/src/afl-forkserver.c +++ b/src/afl-forkserver.c @@ -213,7 +213,7 @@ restart_select: static void afl_fauxsrv_execv(afl_forkserver_t *fsrv, char **argv) { unsigned char tmp[4] = {0, 0, 0, 0}; - pid_t child_pid = -1; + pid_t child_pid; if (!be_quiet) { ACTF("Using Fauxserver:"); } @@ -1104,7 +1104,7 @@ fsrv_run_result_t afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 timeout, "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" + " to something higher than %llu.\n" " - The binary or one of the libraries it uses manages to " "create\n" " threads before the forkserver initializes.\n" -- cgit 1.4.1 From 9cdf5c415015e4e80b577c021b8b9fcf8a3d58fb Mon Sep 17 00:00:00 2001 From: buherator Date: Thu, 7 Jan 2021 22:35:34 +0100 Subject: User defined kill signal value (#678) * Adding AFL_KILL_SIGNAL environment variable Controlling the kill signal used to end forked processes. * Checking validity of AFL_KILL_SIGNAL env variable This commit also sets a valid value in the environment to avoid duplicating code in at_exit(). Changing data type of fsrv->kill_signal to u8 to match last_kill_signal. * Adding afl_kill_signal to AFL (environment) state This commit simply introduces a struct member for future use. The env variable is not used from the afl struct but from fsrv, where its validity is checked, resulting in a FATAL in case of errors. --- include/afl-fuzz.h | 2 +- include/envs.h | 1 + include/forkserver.h | 2 ++ src/afl-forkserver.c | 44 +++++++++++++++++++++++++++++++++++++++----- src/afl-fuzz-state.c | 11 +++++++++-- src/afl-fuzz.c | 13 +++++++++++-- 6 files changed, 63 insertions(+), 10 deletions(-) (limited to 'src/afl-forkserver.c') diff --git a/include/afl-fuzz.h b/include/afl-fuzz.h index ede54f0e..988a907d 100644 --- a/include/afl-fuzz.h +++ b/include/afl-fuzz.h @@ -381,7 +381,7 @@ typedef struct afl_env_vars { *afl_hang_tmout, *afl_forksrv_init_tmout, *afl_skip_crashes, *afl_preload, *afl_max_det_extras, *afl_statsd_host, *afl_statsd_port, *afl_crash_exitcode, *afl_statsd_tags_flavor, *afl_testcache_size, - *afl_testcache_entries; + *afl_testcache_entries, *afl_kill_signal; } afl_env_vars_t; diff --git a/include/envs.h b/include/envs.h index e4e49c4d..97367fae 100644 --- a/include/envs.h +++ b/include/envs.h @@ -61,6 +61,7 @@ static char *afl_environment_variables[] = { "AFL_IMPORT_FIRST", "AFL_INST_LIBS", "AFL_INST_RATIO", + "AFL_KILL_SIGNAL", "AFL_KEEP_TRACES", "AFL_KEEP_ASSEMBLY", "AFL_LD_HARD_FAIL", diff --git a/include/forkserver.h b/include/forkserver.h index 8e029266..3019e289 100644 --- a/include/forkserver.h +++ b/include/forkserver.h @@ -99,6 +99,8 @@ typedef struct afl_forkserver { void (*add_extra_func)(void *afl_ptr, u8 *mem, u32 len); + u8 kill_signal; + } afl_forkserver_t; typedef enum fsrv_run_result { diff --git a/src/afl-forkserver.c b/src/afl-forkserver.c index d6195cb5..70fb9572 100644 --- a/src/afl-forkserver.c +++ b/src/afl-forkserver.c @@ -95,6 +95,29 @@ void afl_fsrv_init(afl_forkserver_t *fsrv) { fsrv->uses_asan = false; fsrv->init_child_func = fsrv_exec_child; + fsrv->kill_signal = SIGKILL; + + char *kill_signal_env = get_afl_env("AFL_KILL_SIGNAL"); + if (kill_signal_env) { + + char *endptr; + u8 signal_code; + signal_code = (u8)strtoul(kill_signal_env, &endptr, 10); + /* Did we manage to parse the full string? */ + if (*endptr != '\0' || endptr == kill_signal_env) { + + FATAL("Invalid kill signal value!"); + + } + + fsrv->kill_signal = signal_code; + + } else { + + /* Using hardcoded code for SIGKILL for the sake of simplicity */ + setenv("AFL_KILL_SIGNAL", "9", 1); + + } list_append(&fsrv_list, fsrv); @@ -126,6 +149,8 @@ void afl_fsrv_init_dup(afl_forkserver_t *fsrv_to, afl_forkserver_t *from) { fsrv_to->init_child_func = from->init_child_func; // Note: do not copy ->add_extra_func + fsrv_to->kill_signal = from->kill_signal; + list_append(&fsrv_list, fsrv_to); } @@ -559,12 +584,12 @@ void afl_fsrv_start(afl_forkserver_t *fsrv, char **argv, if (!time_ms) { - kill(fsrv->fsrv_pid, SIGKILL); + kill(fsrv->fsrv_pid, fsrv->kill_signal); } else if (time_ms > fsrv->init_tmout) { fsrv->last_run_timed_out = 1; - kill(fsrv->fsrv_pid, SIGKILL); + kill(fsrv->fsrv_pid, fsrv->kill_signal); } else { @@ -944,10 +969,10 @@ void afl_fsrv_start(afl_forkserver_t *fsrv, char **argv, static void afl_fsrv_kill(afl_forkserver_t *fsrv) { - if (fsrv->child_pid > 0) { kill(fsrv->child_pid, SIGKILL); } + if (fsrv->child_pid > 0) { kill(fsrv->child_pid, fsrv->kill_signal); } if (fsrv->fsrv_pid > 0) { - kill(fsrv->fsrv_pid, SIGKILL); + kill(fsrv->fsrv_pid, fsrv->kill_signal); if (waitpid(fsrv->fsrv_pid, NULL, 0) <= 0) { WARNF("error waitpid\n"); } } @@ -1091,7 +1116,7 @@ fsrv_run_result_t afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 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); + kill(fsrv->child_pid, fsrv->kill_signal); fsrv->last_run_timed_out = 1; if (read(fsrv->fsrv_st_fd, &fsrv->child_status, 4) < 4) { exec_ms = 0; } @@ -1137,6 +1162,15 @@ fsrv_run_result_t afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 timeout, /* Report outcome to caller. */ + /* TODO We use SIGTERM here as an indicator of Xen mode, + although it's not equivalent! */ + if (fsrv->kill_signal == SIGTERM && !*stop_soon_p && + fsrv->last_run_timed_out) { + + return FSRV_RUN_TMOUT; + + } + if (WIFSIGNALED(fsrv->child_status) && !*stop_soon_p) { fsrv->last_kill_signal = WTERMSIG(fsrv->child_status); diff --git a/src/afl-fuzz-state.c b/src/afl-fuzz-state.c index 34456c0d..60c9684c 100644 --- a/src/afl-fuzz-state.c +++ b/src/afl-fuzz-state.c @@ -418,6 +418,13 @@ void read_afl_environment(afl_state_t *afl, char **envp) { (u8 *)get_afl_env(afl_environment_variables[i]); #endif + } else if (!strncmp(env, "AFL_KILL_SIGNAL", + + afl_environment_variable_len)) { + + afl->afl_env.afl_kill_signal = + (u8 *)get_afl_env(afl_environment_variables[i]); + } } else { @@ -524,8 +531,8 @@ void afl_states_stop(void) { LIST_FOREACH(&afl_states, afl_state_t, { - if (el->fsrv.child_pid > 0) kill(el->fsrv.child_pid, SIGKILL); - if (el->fsrv.fsrv_pid > 0) kill(el->fsrv.fsrv_pid, SIGKILL); + if (el->fsrv.child_pid > 0) kill(el->fsrv.child_pid, el->fsrv.kill_signal); + if (el->fsrv.fsrv_pid > 0) kill(el->fsrv.fsrv_pid, el->fsrv.kill_signal); }); diff --git a/src/afl-fuzz.c b/src/afl-fuzz.c index 063134fb..00625f2e 100644 --- a/src/afl-fuzz.c +++ b/src/afl-fuzz.c @@ -76,8 +76,17 @@ static void at_exit() { } - if (pid1 > 0) { kill(pid1, SIGKILL); } - if (pid2 > 0) { kill(pid2, SIGKILL); } + u8 kill_signal = SIGKILL; + + /* AFL_KILL_SIGNAL should already be initialized by afl_fsrv_init() */ + if (getenv("AFL_KILL_SIGNAL")) { + + kill_signal = atoi(getenv("AFL_KILL_SIGNAL")); + + } + + if (pid1 > 0) { kill(pid1, kill_signal); } + if (pid2 > 0) { kill(pid2, kill_signal); } } -- cgit 1.4.1 From a06b25538fd7b6eef6755094aa4678c2cb5333fd Mon Sep 17 00:00:00 2001 From: Dominik Maier Date: Thu, 7 Jan 2021 23:21:10 +0100 Subject: cleaned up AFL_KILL_SIGNAL --- afl-cmin | 1 + docs/Changelog.md | 2 +- docs/env_variables.md | 4 ++++ src/afl-forkserver.c | 45 +++++++-------------------------------------- src/afl-fuzz.c | 30 +++++++++++++++++++++++++++++- src/afl-showmap.c | 37 +++++++++++++++++++++++++++++++++---- src/afl-tmin.c | 29 +++++++++++++++++++++++++++++ 7 files changed, 104 insertions(+), 44 deletions(-) (limited to 'src/afl-forkserver.c') diff --git a/afl-cmin b/afl-cmin index eef2b7ef..726e90ab 100755 --- a/afl-cmin +++ b/afl-cmin @@ -120,6 +120,7 @@ function usage() { "AFL_CRASH_EXITCODE: optional child exit code to be interpreted as crash\n" \ "AFL_FORKSRV_INIT_TMOUT: time the fuzzer waits for the target to come up, initially\n" \ "AFL_KEEP_TRACES: leave the temporary /.traces directory\n" \ +"AFL_KILL_SIGNAL: Signal ID delivered to child processes on timeout, etc. (default: SIGKILL)\n" "AFL_PATH: path for the afl-showmap binary if not found anywhere else\n" \ "AFL_SKIP_BIN_CHECK: skip check for target binary\n" exit 1 diff --git a/docs/Changelog.md b/docs/Changelog.md index 03b8e036..81ac91b0 100644 --- a/docs/Changelog.md +++ b/docs/Changelog.md @@ -32,7 +32,7 @@ sending a mail to . already building with all cores, the gcc plugin needs only one. - added dummy Makefile to instrumentation/ - Updated utils/afl_frida to be 5% faster - + - Added AFL_KILL_SIGNAL env variable for custom targets (thanks @v-p-b) ### Version ++3.00c (release) - llvm_mode/ and gcc_plugin/ moved to instrumentation/ diff --git a/docs/env_variables.md b/docs/env_variables.md index e6b9381b..26128b01 100644 --- a/docs/env_variables.md +++ b/docs/env_variables.md @@ -350,6 +350,10 @@ checks or alter some of the more exotic semantics of the tool: - Note that `AFL_POST_LIBRARY` is deprecated, use `AFL_CUSTOM_MUTATOR_LIBRARY` instead (see below). + - `AFL_KILL_SIGNAL`: Set the signal ID to be delivered to child processes on timeout. + Unless you implement your own targets or instrumentation, you likely don't have to set it. + By default, on timeout and on exit, `SIGKILL` (`AFL_KILL_SIGNAL=9`) will be delivered to the child. + - Setting `AFL_CUSTOM_MUTATOR_LIBRARY` to a shared library with afl_custom_fuzz() creates additional mutations through this library. If afl-fuzz is compiled with Python (which is autodetected during builing diff --git a/src/afl-forkserver.c b/src/afl-forkserver.c index 70fb9572..b7aa87f8 100644 --- a/src/afl-forkserver.c +++ b/src/afl-forkserver.c @@ -84,6 +84,7 @@ void afl_fsrv_init(afl_forkserver_t *fsrv) { fsrv->init_tmout = EXEC_TIMEOUT * FORK_WAIT_MULT; fsrv->mem_limit = MEM_LIMIT; fsrv->out_file = NULL; + fsrv->kill_signal = SIGKILL; /* exec related stuff */ fsrv->child_pid = -1; @@ -95,30 +96,6 @@ void afl_fsrv_init(afl_forkserver_t *fsrv) { fsrv->uses_asan = false; fsrv->init_child_func = fsrv_exec_child; - fsrv->kill_signal = SIGKILL; - - char *kill_signal_env = get_afl_env("AFL_KILL_SIGNAL"); - if (kill_signal_env) { - - char *endptr; - u8 signal_code; - signal_code = (u8)strtoul(kill_signal_env, &endptr, 10); - /* Did we manage to parse the full string? */ - if (*endptr != '\0' || endptr == kill_signal_env) { - - FATAL("Invalid kill signal value!"); - - } - - fsrv->kill_signal = signal_code; - - } else { - - /* Using hardcoded code for SIGKILL for the sake of simplicity */ - setenv("AFL_KILL_SIGNAL", "9", 1); - - } - list_append(&fsrv_list, fsrv); } @@ -139,6 +116,7 @@ void afl_fsrv_init_dup(afl_forkserver_t *fsrv_to, afl_forkserver_t *from) { fsrv_to->no_unlink = from->no_unlink; fsrv_to->uses_crash_exitcode = from->uses_crash_exitcode; fsrv_to->crash_exitcode = from->crash_exitcode; + fsrv_to->kill_signal = from->kill_signal; // These are forkserver specific. fsrv_to->out_dir_fd = -1; @@ -149,8 +127,6 @@ void afl_fsrv_init_dup(afl_forkserver_t *fsrv_to, afl_forkserver_t *from) { fsrv_to->init_child_func = from->init_child_func; // Note: do not copy ->add_extra_func - fsrv_to->kill_signal = from->kill_signal; - list_append(&fsrv_list, fsrv_to); } @@ -1162,25 +1138,18 @@ fsrv_run_result_t afl_fsrv_run_target(afl_forkserver_t *fsrv, u32 timeout, /* Report outcome to caller. */ - /* TODO We use SIGTERM here as an indicator of Xen mode, - although it's not equivalent! */ - if (fsrv->kill_signal == SIGTERM && !*stop_soon_p && - fsrv->last_run_timed_out) { + /* Did we timeout? */ + if (unlikely(fsrv->last_run_timed_out)) { + fsrv->last_kill_signal = fsrv->kill_signal; return FSRV_RUN_TMOUT; } - if (WIFSIGNALED(fsrv->child_status) && !*stop_soon_p) { + /* Did we crash? */ + if (unlikely(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; } diff --git a/src/afl-fuzz.c b/src/afl-fuzz.c index 00625f2e..5c363c63 100644 --- a/src/afl-fuzz.c +++ b/src/afl-fuzz.c @@ -194,10 +194,11 @@ static void usage(u8 *argv0, int more_help) { "AFL_EXPAND_HAVOC_NOW: immediately enable expand havoc mode (default: after 60 minutes and a cycle without finds)\n" "AFL_FAST_CAL: limit the calibration stage to three cycles for speedup\n" "AFL_FORCE_UI: force showing the status screen (for virtual consoles)\n" - "AFL_HANG_TMOUT: override timeout value (in milliseconds)\n" "AFL_FORKSRV_INIT_TMOUT: time spent waiting for forkserver during startup (in milliseconds)\n" + "AFL_HANG_TMOUT: override timeout value (in milliseconds)\n" "AFL_I_DONT_CARE_ABOUT_MISSING_CRASHES: don't warn about core dump handlers\n" "AFL_IMPORT_FIRST: sync and import test cases from other fuzzer instances first\n" + "AFL_KILL_SIGNAL: Signal ID delivered to child processes on timeout, etc. (default: SIGKILL)\n" "AFL_MAP_SIZE: the shared memory size for that target. must be >= the size\n" " the target was compiled for\n" "AFL_MAX_DET_EXTRAS: if more entries are in the dictionary list than this value\n" @@ -986,6 +987,33 @@ int main(int argc, char **argv_orig, char **envp) { #endif + afl->fsrv.kill_signal = SIGKILL; + if (afl->afl_env.afl_kill_signal) { + + char *endptr; + u8 signal_code; + signal_code = (u8)strtoul(afl->afl_env.afl_kill_signal, &endptr, 10); + /* Did we manage to parse the full string? */ + if (*endptr != '\0' || endptr == (char *)afl->afl_env.afl_kill_signal) { + + FATAL("Invalid AFL_KILL_SIGNAL: %s (expected unsigned int)", + afl->afl_env.afl_kill_signal); + + } + + afl->fsrv.kill_signal = signal_code; + + } else { + + char *sigstr = alloc_printf("%d", (int)SIGKILL); + if (!sigstr) { FATAL("Failed to alloc mem for signal buf"); } + + /* Set the env for signal handler */ + setenv("AFL_KILL_SIGNAL", sigstr, 1); + free(sigstr); + + } + setup_signal_handlers(); check_asan_opts(afl); diff --git a/src/afl-showmap.c b/src/afl-showmap.c index d50601fc..2c9c38ed 100644 --- a/src/afl-showmap.c +++ b/src/afl-showmap.c @@ -693,12 +693,13 @@ static void usage(u8 *argv0) { "AFL_CRASH_EXITCODE: optional child exit code to be interpreted as " "crash\n" "AFL_DEBUG: enable extra developer output\n" - "AFL_MAP_SIZE: the shared memory size for that target. must be >= the " - "size\n" - " the target was compiled for\n" - "AFL_PRELOAD: LD_PRELOAD / DYLD_INSERT_LIBRARIES settings for target\n" "AFL_FORKSRV_INIT_TMOUT: time spent waiting for forkserver during " "startup (in milliseconds)\n" + "AFL_KILL_SIGNAL: Signal ID delivered to child processes on timeout, " + "etc. (default: SIGKILL)\n" + "AFL_MAP_SIZE: the shared memory size for that target. must be >= the " + "size the target was compiled for\n" + "AFL_PRELOAD: LD_PRELOAD / DYLD_INSERT_LIBRARIES settings for target\n" "AFL_QUIET: do not print extra informational output\n", argv0, MEM_LIMIT, doc_path); @@ -1115,6 +1116,34 @@ int main(int argc, char **argv_orig, char **envp) { } + fsrv->kill_signal = SIGKILL; + char *afl_kill_signal_env = getenv("AFL_KILL_SIGNAL"); + if (afl_kill_signal_env && afl_kill_signal_env[0]) { + + char *endptr; + u8 signal_code; + signal_code = (u8)strtoul(afl_kill_signal_env, &endptr, 10); + /* Did we manage to parse the full string? */ + if (*endptr != '\0' || endptr == afl_kill_signal_env) { + + FATAL("Invalid AFL_KILL_SIGNAL: %s (expected unsigned int)", + afl_kill_signal_env); + + } + + fsrv->kill_signal = signal_code; + + } else { + + char *sigstr = alloc_printf("%d", (int)SIGKILL); + if (!sigstr) { FATAL("Failed to alloc mem for signal buf"); } + + /* Set the env for signal handler */ + setenv("AFL_KILL_SIGNAL", sigstr, 1); + free(sigstr); + + } + if (getenv("AFL_CRASH_EXITCODE")) { long exitcode = strtol(getenv("AFL_CRASH_EXITCODE"), NULL, 10); diff --git a/src/afl-tmin.c b/src/afl-tmin.c index 09d97f58..342de9c8 100644 --- a/src/afl-tmin.c +++ b/src/afl-tmin.c @@ -855,6 +855,7 @@ static void usage(u8 *argv0) { "Environment variables used:\n" "AFL_CRASH_EXITCODE: optional child exit code to be interpreted as crash\n" "AFL_FORKSRV_INIT_TMOUT: time spent waiting for forkserver during startup (in milliseconds)\n" + "AFL_KILL_SIGNAL: Signal ID delivered to child processes on timeout, etc. (default: SIGKILL)\n" "AFL_MAP_SIZE: the shared memory size for that target. must be >= the size\n" " the target was compiled for\n" "AFL_PRELOAD: LD_PRELOAD / DYLD_INSERT_LIBRARIES settings for target\n" @@ -1134,6 +1135,34 @@ int main(int argc, char **argv_orig, char **envp) { } + fsrv->kill_signal = SIGKILL; + char *afl_kill_signal_env = getenv("AFL_KILL_SIGNAL"); + if (afl_kill_signal_env && afl_kill_signal_env[0]) { + + char *endptr; + u8 signal_code; + signal_code = (u8)strtoul(afl_kill_signal_env, &endptr, 10); + /* Did we manage to parse the full string? */ + if (*endptr != '\0' || endptr == afl_kill_signal_env) { + + FATAL("Invalid AFL_KILL_SIGNAL: %s (expected unsigned int)", + afl_kill_signal_env); + + } + + fsrv->kill_signal = signal_code; + + } else { + + char *sigstr = alloc_printf("%d", (int)SIGKILL); + if (!sigstr) { FATAL("Failed to alloc mem for signal buf"); } + + /* Set the env for signal handler */ + setenv("AFL_KILL_SIGNAL", sigstr, 1); + free(sigstr); + + } + if (getenv("AFL_CRASH_EXITCODE")) { long exitcode = strtol(getenv("AFL_CRASH_EXITCODE"), NULL, 10); -- cgit 1.4.1