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executor.cc
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// Copyright 2017 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
// +build
#include <algorithm>
#include <errno.h>
#include <limits.h>
#include <signal.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "defs.h"
#if defined(__GNUC__)
#define SYSCALLAPI
#define NORETURN __attribute__((noreturn))
#define ALIGNED(N) __attribute__((aligned(N)))
#define PRINTF(fmt, args) __attribute__((format(printf, fmt, args)))
#else
// Assuming windows/cl.
#define SYSCALLAPI WINAPI
#define NORETURN __declspec(noreturn)
#define ALIGNED(N) __declspec(align(N))
#define PRINTF(fmt, args)
#endif
#ifndef GIT_REVISION
#define GIT_REVISION "unknown"
#endif
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
// uint64 is impossible to printf without using the clumsy and verbose "%" PRId64.
// So we define and use uint64. Note: pkg/csource does s/uint64/uint64/.
// Also define uint32/16/8 for consistency.
typedef unsigned long long uint64;
typedef unsigned int uint32;
typedef unsigned short uint16;
typedef unsigned char uint8;
// exit/_exit do not necessary work (e.g. if fuzzer sets seccomp filter that prohibits exit_group).
// Use doexit instead. We must redefine exit to something that exists in stdlib,
// because some standard libraries contain "using ::exit;", but has different signature.
#define exit vsnprintf
// Dynamic memory allocation reduces test reproducibility across different libc versions and kernels.
// malloc will cause unspecified number of additional mmap's at unspecified locations.
// For small objects prefer stack allocations, for larger -- either global objects (this may have
// issues with concurrency), or controlled mmaps, or make the fuzzer allocate memory.
#define malloc do_not_use_malloc
#define calloc do_not_use_calloc
// Note: zircon max fd is 256.
// Some common_OS.h files know about this constant for RLIMIT_NOFILE.
const int kMaxFd = 250;
const int kMaxThreads = 16;
const int kInPipeFd = kMaxFd - 1; // remapped from stdin
const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
const int kCoverFd = kOutPipeFd - kMaxThreads;
const int kMaxArgs = 9;
const int kCoverSize = 256 << 10;
const int kFailStatus = 67;
// Logical error (e.g. invalid input program), use as an assert() alternative.
static NORETURN PRINTF(1, 2) void fail(const char* msg, ...);
// Just exit (e.g. due to temporal ENOMEM error).
static NORETURN PRINTF(1, 2) void exitf(const char* msg, ...);
static NORETURN void doexit(int status);
// Print debug output that is visible when running syz-manager/execprog with -debug flag.
// Debug output is supposed to be relatively high-level (syscalls executed, return values, timing, etc)
// and is intended mostly for end users. If you need to debug lower-level details, use debug_verbose
// function and temporary enable it in your build by changing #if 0 below.
// This function does not add \n at the end of msg as opposed to the previous functions.
static PRINTF(1, 2) void debug(const char* msg, ...);
void debug_dump_data(const char* data, int length);
#if 0
#define debug_verbose(...) debug(__VA_ARGS__)
#else
#define debug_verbose(...) (void)0
#endif
static void receive_execute();
static void reply_execute(int status);
#if GOOS_akaros
static void resend_execute(int fd);
#endif
#if SYZ_EXECUTOR_USES_FORK_SERVER
static void receive_handshake();
static void reply_handshake();
#endif
#if SYZ_EXECUTOR_USES_SHMEM
const int kMaxOutput = 16 << 20;
const int kInFd = 3;
const int kOutFd = 4;
static uint32* output_data;
static uint32* output_pos;
static uint32* write_output(uint32 v);
static uint32* write_output_64(uint64 v);
static void write_completed(uint32 completed);
static uint32 hash(uint32 a);
static bool dedup(uint32 sig);
#endif
uint64 start_time_ms = 0;
static bool flag_debug;
static bool flag_coverage;
static bool flag_sandbox_none;
static bool flag_sandbox_setuid;
static bool flag_sandbox_namespace;
static bool flag_sandbox_android;
static bool flag_extra_coverage;
static bool flag_net_injection;
static bool flag_net_devices;
static bool flag_net_reset;
static bool flag_cgroups;
static bool flag_close_fds;
static bool flag_devlink_pci;
static bool flag_vhci_injection;
static bool flag_wifi;
static bool flag_collect_cover;
static bool flag_dedup_cover;
static bool flag_threaded;
static bool flag_collide;
// If true, then executor should write the comparisons data to fuzzer.
static bool flag_comparisons;
// Inject fault into flag_fault_nth-th operation in flag_fault_call-th syscall.
static bool flag_fault;
static int flag_fault_call;
static int flag_fault_nth;
#define SYZ_EXECUTOR 1
#include "common.h"
const int kMaxInput = 4 << 20; // keep in sync with prog.ExecBufferSize
const int kMaxCommands = 1000;
const uint64 instr_eof = -1;
const uint64 instr_copyin = -2;
const uint64 instr_copyout = -3;
const uint64 arg_const = 0;
const uint64 arg_result = 1;
const uint64 arg_data = 2;
const uint64 arg_csum = 3;
const uint64 binary_format_native = 0;
const uint64 binary_format_bigendian = 1;
const uint64 binary_format_strdec = 2;
const uint64 binary_format_strhex = 3;
const uint64 binary_format_stroct = 4;
const uint64 no_copyout = -1;
static int running;
static bool collide;
uint32 completed;
bool is_kernel_64_bit = true;
ALIGNED(64 << 10)
static char input_data[kMaxInput];
// Checksum kinds.
static const uint64 arg_csum_inet = 0;
// Checksum chunk kinds.
static const uint64 arg_csum_chunk_data = 0;
static const uint64 arg_csum_chunk_const = 1;
typedef intptr_t(SYSCALLAPI* syscall_t)(intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t, intptr_t);
struct call_t {
const char* name;
int sys_nr;
call_attrs_t attrs;
syscall_t call;
};
struct cover_t {
int fd;
uint32 size;
char* data;
char* data_end;
};
struct thread_t {
int id;
bool created;
event_t ready;
event_t done;
uint64* copyout_pos;
uint64 copyout_index;
bool colliding;
bool executing;
int call_index;
int call_num;
int num_args;
intptr_t args[kMaxArgs];
intptr_t res;
uint32 reserrno;
bool fault_injected;
cover_t cov;
bool soft_fail_state;
};
static thread_t threads[kMaxThreads];
static thread_t* last_scheduled;
// Threads use this variable to access information about themselves.
static __thread struct thread_t* current_thread;
static cover_t extra_cov;
struct res_t {
bool executed;
uint64 val;
};
static res_t results[kMaxCommands];
const uint64 kInMagic = 0xbadc0ffeebadface;
const uint32 kOutMagic = 0xbadf00d;
struct handshake_req {
uint64 magic;
uint64 flags; // env flags
uint64 pid;
};
struct handshake_reply {
uint32 magic;
};
struct execute_req {
uint64 magic;
uint64 env_flags;
uint64 exec_flags;
uint64 pid;
uint64 fault_call;
uint64 fault_nth;
uint64 prog_size;
};
struct execute_reply {
uint32 magic;
uint32 done;
uint32 status;
};
// call_reply.flags
const uint32 call_flag_executed = 1 << 0;
const uint32 call_flag_finished = 1 << 1;
const uint32 call_flag_blocked = 1 << 2;
const uint32 call_flag_fault_injected = 1 << 3;
struct call_reply {
execute_reply header;
uint32 call_index;
uint32 call_num;
uint32 reserrno;
uint32 flags;
uint32 signal_size;
uint32 cover_size;
uint32 comps_size;
// signal/cover/comps follow
};
enum {
KCOV_CMP_CONST = 1,
KCOV_CMP_SIZE1 = 0,
KCOV_CMP_SIZE2 = 2,
KCOV_CMP_SIZE4 = 4,
KCOV_CMP_SIZE8 = 6,
KCOV_CMP_SIZE_MASK = 6,
};
struct kcov_comparison_t {
// Note: comparisons are always 64-bits regardless of kernel bitness.
uint64 type;
uint64 arg1;
uint64 arg2;
uint64 pc;
bool ignore() const;
void write();
bool operator==(const struct kcov_comparison_t& other) const;
bool operator<(const struct kcov_comparison_t& other) const;
};
typedef char kcov_comparison_size[sizeof(kcov_comparison_t) == 4 * sizeof(uint64) ? 1 : -1];
struct feature_t {
const char* name;
void (*setup)();
};
static thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos);
static void handle_completion(thread_t* th);
static void copyout_call_results(thread_t* th);
static void write_call_output(thread_t* th, bool finished);
static void write_extra_output();
static void execute_call(thread_t* th);
static void thread_create(thread_t* th, int id);
static void* worker_thread(void* arg);
static uint64 read_input(uint64** input_posp, bool peek = false);
static uint64 read_arg(uint64** input_posp);
static uint64 read_const_arg(uint64** input_posp, uint64* size_p, uint64* bf, uint64* bf_off_p, uint64* bf_len_p);
static uint64 read_result(uint64** input_posp);
static uint64 swap(uint64 v, uint64 size, uint64 bf);
static void copyin(char* addr, uint64 val, uint64 size, uint64 bf, uint64 bf_off, uint64 bf_len);
static bool copyout(char* addr, uint64 size, uint64* res);
static void setup_control_pipes();
static void setup_features(char** enable, int n);
#include "syscalls.h"
#if GOOS_linux
#include "executor_linux.h"
#elif GOOS_fuchsia
#include "executor_fuchsia.h"
#elif GOOS_akaros
#include "executor_akaros.h"
#elif GOOS_freebsd || GOOS_netbsd || GOOS_openbsd
#include "executor_bsd.h"
#elif GOOS_windows
#include "executor_windows.h"
#elif GOOS_test
#include "executor_test.h"
#else
#error "unknown OS"
#endif
#include "test.h"
int main(int argc, char** argv)
{
if (argc == 2 && strcmp(argv[1], "version") == 0) {
puts(GOOS " " GOARCH " " SYZ_REVISION " " GIT_REVISION);
return 0;
}
if (argc >= 2 && strcmp(argv[1], "setup") == 0) {
setup_features(argv + 2, argc - 2);
return 0;
}
if (argc >= 2 && strcmp(argv[1], "leak") == 0) {
#if SYZ_HAVE_LEAK_CHECK
check_leaks(argv + 2, argc - 2);
#else
fail("leak checking is not implemented");
#endif
return 0;
}
if (argc >= 2 && strcmp(argv[1], "setup_kcsan_filterlist") == 0) {
#if SYZ_HAVE_KCSAN
setup_kcsan_filterlist(argv + 2, argc - 2, true);
#else
fail("KCSAN is not implemented");
#endif
return 0;
}
if (argc == 2 && strcmp(argv[1], "test") == 0)
return run_tests();
start_time_ms = current_time_ms();
os_init(argc, argv, (char*)SYZ_DATA_OFFSET, SYZ_NUM_PAGES * SYZ_PAGE_SIZE);
current_thread = &threads[0];
#if SYZ_EXECUTOR_USES_SHMEM
if (mmap(&input_data[0], kMaxInput, PROT_READ, MAP_PRIVATE | MAP_FIXED, kInFd, 0) != &input_data[0])
fail("mmap of input file failed");
// The output region is the only thing in executor process for which consistency matters.
// If it is corrupted ipc package will fail to parse its contents and panic.
// But fuzzer constantly invents new ways of how to currupt the region,
// so we map the region at a (hopefully) hard to guess address with random offset,
// surrounded by unmapped pages.
// The address chosen must also work on 32-bit kernels with 1GB user address space.
void* preferred = (void*)(0x1b2bc20000ull + (1 << 20) * (getpid() % 128));
output_data = (uint32*)mmap(preferred, kMaxOutput,
PROT_READ | PROT_WRITE, MAP_SHARED | MAP_FIXED, kOutFd, 0);
if (output_data != preferred)
fail("mmap of output file failed");
// Prevent test programs to mess with these fds.
// Due to races in collider mode, a program can e.g. ftruncate one of these fds,
// which will cause fuzzer to crash.
close(kInFd);
close(kOutFd);
#endif
use_temporary_dir();
install_segv_handler();
setup_control_pipes();
#if SYZ_EXECUTOR_USES_FORK_SERVER
receive_handshake();
#else
receive_execute();
#endif
if (flag_coverage) {
for (int i = 0; i < kMaxThreads; i++) {
threads[i].cov.fd = kCoverFd + i;
cover_open(&threads[i].cov, false);
cover_protect(&threads[i].cov);
}
cover_open(&extra_cov, true);
cover_protect(&extra_cov);
if (flag_extra_coverage) {
// Don't enable comps because we don't use them in the fuzzer yet.
cover_enable(&extra_cov, false, true);
}
}
int status = 0;
if (flag_sandbox_none)
status = do_sandbox_none();
#if SYZ_HAVE_SANDBOX_SETUID
else if (flag_sandbox_setuid)
status = do_sandbox_setuid();
#endif
#if SYZ_HAVE_SANDBOX_NAMESPACE
else if (flag_sandbox_namespace)
status = do_sandbox_namespace();
#endif
#if SYZ_HAVE_SANDBOX_ANDROID
else if (flag_sandbox_android)
status = do_sandbox_android();
#endif
else
fail("unknown sandbox type");
#if SYZ_EXECUTOR_USES_FORK_SERVER
fprintf(stderr, "loop exited with status %d\n", status);
// Other statuses happen when fuzzer processes manages to kill loop, e.g. with:
// ptrace(PTRACE_SEIZE, 1, 0, 0x100040)
if (status != kFailStatus)
status = 0;
// If an external sandbox process wraps executor, the out pipe will be closed
// before the sandbox process exits this will make ipc package kill the sandbox.
// As the result sandbox process will exit with exit status 9 instead of the executor
// exit status (notably kFailStatus). So we duplicate the exit status on the pipe.
reply_execute(status);
doexit(status);
// Unreachable.
return 1;
#else
reply_execute(status);
return status;
#endif
}
void setup_control_pipes()
{
if (dup2(0, kInPipeFd) < 0)
fail("dup2(0, kInPipeFd) failed");
if (dup2(1, kOutPipeFd) < 0)
fail("dup2(1, kOutPipeFd) failed");
if (dup2(2, 1) < 0)
fail("dup2(2, 1) failed");
// We used to close(0), but now we dup stderr to stdin to keep fd numbers
// stable across executor and C programs generated by pkg/csource.
if (dup2(2, 0) < 0)
fail("dup2(2, 0) failed");
}
void parse_env_flags(uint64 flags)
{
// Note: Values correspond to ordering in pkg/ipc/ipc.go, e.g. FlagSandboxNamespace
flag_debug = flags & (1 << 0);
flag_coverage = flags & (1 << 1);
if (flags & (1 << 2))
flag_sandbox_setuid = true;
else if (flags & (1 << 3))
flag_sandbox_namespace = true;
else if (flags & (1 << 4))
flag_sandbox_android = true;
else
flag_sandbox_none = true;
flag_extra_coverage = flags & (1 << 5);
flag_net_injection = flags & (1 << 6);
flag_net_devices = flags & (1 << 7);
flag_net_reset = flags & (1 << 8);
flag_cgroups = flags & (1 << 9);
flag_close_fds = flags & (1 << 10);
flag_devlink_pci = flags & (1 << 11);
flag_vhci_injection = flags & (1 << 12);
flag_wifi = flags & (1 << 13);
}
#if SYZ_EXECUTOR_USES_FORK_SERVER
void receive_handshake()
{
handshake_req req = {};
int n = read(kInPipeFd, &req, sizeof(req));
if (n != sizeof(req))
fail("handshake read failed: %d", n);
if (req.magic != kInMagic)
fail("bad handshake magic 0x%llx", req.magic);
parse_env_flags(req.flags);
procid = req.pid;
}
void reply_handshake()
{
handshake_reply reply = {};
reply.magic = kOutMagic;
if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
fail("control pipe write failed");
}
#endif
static execute_req last_execute_req;
void receive_execute()
{
execute_req& req = last_execute_req;
if (read(kInPipeFd, &req, sizeof(req)) != (ssize_t)sizeof(req))
fail("control pipe read failed");
if (req.magic != kInMagic)
fail("bad execute request magic 0x%llx", req.magic);
if (req.prog_size > kMaxInput)
fail("bad execute prog size 0x%llx", req.prog_size);
parse_env_flags(req.env_flags);
procid = req.pid;
flag_collect_cover = req.exec_flags & (1 << 0);
flag_dedup_cover = req.exec_flags & (1 << 1);
flag_fault = req.exec_flags & (1 << 2);
flag_comparisons = req.exec_flags & (1 << 3);
flag_threaded = req.exec_flags & (1 << 4);
flag_collide = req.exec_flags & (1 << 5);
flag_fault_call = req.fault_call;
flag_fault_nth = req.fault_nth;
if (!flag_threaded)
flag_collide = false;
debug("[%llums] exec opts: procid=%llu threaded=%d collide=%d cover=%d comps=%d dedup=%d fault=%d/%d/%d prog=%llu\n",
current_time_ms() - start_time_ms, procid, flag_threaded, flag_collide,
flag_collect_cover, flag_comparisons, flag_dedup_cover, flag_fault,
flag_fault_call, flag_fault_nth, req.prog_size);
if (SYZ_EXECUTOR_USES_SHMEM) {
if (req.prog_size)
fail("need_prog: no program");
return;
}
if (req.prog_size == 0)
fail("need_prog: no program");
uint64 pos = 0;
for (;;) {
ssize_t rv = read(kInPipeFd, input_data + pos, sizeof(input_data) - pos);
if (rv < 0)
fail("read failed");
pos += rv;
if (rv == 0 || pos >= req.prog_size)
break;
}
if (pos != req.prog_size)
fail("bad input size %lld, want %lld", pos, req.prog_size);
}
#if GOOS_akaros
void resend_execute(int fd)
{
execute_req& req = last_execute_req;
if (write(fd, &req, sizeof(req)) != sizeof(req))
fail("child pipe header write failed");
if (write(fd, input_data, req.prog_size) != (ssize_t)req.prog_size)
fail("child pipe program write failed");
}
#endif
void reply_execute(int status)
{
execute_reply reply = {};
reply.magic = kOutMagic;
reply.done = true;
reply.status = status;
if (write(kOutPipeFd, &reply, sizeof(reply)) != sizeof(reply))
fail("control pipe write failed");
}
// execute_one executes program stored in input_data.
void execute_one()
{
// Duplicate global collide variable on stack.
// Fuzzer once come up with ioctl(fd, FIONREAD, 0x920000),
// where 0x920000 was exactly collide address, so every iteration reset collide to 0.
bool colliding = false;
#if SYZ_EXECUTOR_USES_SHMEM
output_pos = output_data;
write_output(0); // Number of executed syscalls (updated later).
#endif
uint64 start = current_time_ms();
retry:
uint64* input_pos = (uint64*)input_data;
if (flag_coverage && !colliding) {
if (!flag_threaded)
cover_enable(&threads[0].cov, flag_comparisons, false);
if (flag_extra_coverage)
cover_reset(&extra_cov);
}
int call_index = 0;
uint64 prog_extra_timeout = 0;
uint64 prog_extra_cover_timeout = 0;
for (;;) {
uint64 call_num = read_input(&input_pos);
if (call_num == instr_eof)
break;
if (call_num == instr_copyin) {
char* addr = (char*)read_input(&input_pos);
uint64 typ = read_input(&input_pos);
switch (typ) {
case arg_const: {
uint64 size, bf, bf_off, bf_len;
uint64 arg = read_const_arg(&input_pos, &size, &bf, &bf_off, &bf_len);
copyin(addr, arg, size, bf, bf_off, bf_len);
break;
}
case arg_result: {
uint64 meta = read_input(&input_pos);
uint64 size = meta & 0xff;
uint64 bf = meta >> 8;
uint64 val = read_result(&input_pos);
copyin(addr, val, size, bf, 0, 0);
break;
}
case arg_data: {
uint64 size = read_input(&input_pos);
size &= ~(1ull << 63); // readable flag
NONFAILING(memcpy(addr, input_pos, size));
// Read out the data.
for (uint64 i = 0; i < (size + 7) / 8; i++)
read_input(&input_pos);
break;
}
case arg_csum: {
debug_verbose("checksum found at %p\n", addr);
uint64 size = read_input(&input_pos);
char* csum_addr = addr;
uint64 csum_kind = read_input(&input_pos);
switch (csum_kind) {
case arg_csum_inet: {
if (size != 2)
fail("inet checksum must be 2 bytes, not %llu", size);
debug_verbose("calculating checksum for %p\n", csum_addr);
struct csum_inet csum;
csum_inet_init(&csum);
uint64 chunks_num = read_input(&input_pos);
uint64 chunk;
for (chunk = 0; chunk < chunks_num; chunk++) {
uint64 chunk_kind = read_input(&input_pos);
uint64 chunk_value = read_input(&input_pos);
uint64 chunk_size = read_input(&input_pos);
switch (chunk_kind) {
case arg_csum_chunk_data:
debug_verbose("#%lld: data chunk, addr: %llx, size: %llu\n",
chunk, chunk_value, chunk_size);
NONFAILING(csum_inet_update(&csum, (const uint8*)chunk_value, chunk_size));
break;
case arg_csum_chunk_const:
if (chunk_size != 2 && chunk_size != 4 && chunk_size != 8) {
fail("bad checksum const chunk size %lld\n", chunk_size);
}
// Here we assume that const values come to us big endian.
debug_verbose("#%lld: const chunk, value: %llx, size: %llu\n",
chunk, chunk_value, chunk_size);
csum_inet_update(&csum, (const uint8*)&chunk_value, chunk_size);
break;
default:
fail("bad checksum chunk kind %llu", chunk_kind);
}
}
uint16 csum_value = csum_inet_digest(&csum);
debug_verbose("writing inet checksum %hx to %p\n", csum_value, csum_addr);
copyin(csum_addr, csum_value, 2, binary_format_native, 0, 0);
break;
}
default:
fail("bad checksum kind %llu", csum_kind);
}
break;
}
default:
fail("bad argument type %llu", typ);
}
continue;
}
if (call_num == instr_copyout) {
read_input(&input_pos); // index
read_input(&input_pos); // addr
read_input(&input_pos); // size
// The copyout will happen when/if the call completes.
continue;
}
// Normal syscall.
if (call_num >= ARRAY_SIZE(syscalls))
fail("invalid command number %llu", call_num);
const call_t* call = &syscalls[call_num];
if (call->attrs.disabled)
fail("executing disabled syscall %s", call->name);
if (prog_extra_timeout < call->attrs.prog_timeout)
prog_extra_timeout = call->attrs.prog_timeout;
if (strncmp(syscalls[call_num].name, "syz_usb", strlen("syz_usb")) == 0)
prog_extra_cover_timeout = 500;
uint64 copyout_index = read_input(&input_pos);
uint64 num_args = read_input(&input_pos);
if (num_args > kMaxArgs)
fail("command has bad number of arguments %llu", num_args);
uint64 args[kMaxArgs] = {};
for (uint64 i = 0; i < num_args; i++)
args[i] = read_arg(&input_pos);
for (uint64 i = num_args; i < kMaxArgs; i++)
args[i] = 0;
thread_t* th = schedule_call(call_index++, call_num, colliding, copyout_index,
num_args, args, input_pos);
if (colliding && (call_index % 2) == 0) {
// Don't wait for every other call.
// We already have results from the previous execution.
} else if (flag_threaded) {
// Wait for call completion.
// Note: sys/linux knows about this 45 ms timeout when it generates timespec/timeval values.
// Note: pkg/csource also knows about this 45 ms per-call timeout.
uint64 timeout_ms = 45 + call->attrs.timeout;
if (flag_debug && timeout_ms < 1000)
timeout_ms = 1000;
if (event_timedwait(&th->done, timeout_ms))
handle_completion(th);
// Check if any of previous calls have completed.
for (int i = 0; i < kMaxThreads; i++) {
th = &threads[i];
if (th->executing && event_isset(&th->done))
handle_completion(th);
}
} else {
// Execute directly.
if (th != &threads[0])
fail("using non-main thread in non-thread mode");
event_reset(&th->ready);
execute_call(th);
event_set(&th->done);
handle_completion(th);
}
}
if (!colliding && !collide && running > 0) {
// Give unfinished syscalls some additional time.
last_scheduled = 0;
uint64 wait = 100;
uint64 wait_start = current_time_ms();
uint64 wait_end = wait_start + wait;
if (wait_end < start + 800)
wait_end = start + 800;
wait_end += prog_extra_timeout;
while (running > 0 && current_time_ms() <= wait_end) {
sleep_ms(1);
for (int i = 0; i < kMaxThreads; i++) {
thread_t* th = &threads[i];
if (th->executing && event_isset(&th->done))
handle_completion(th);
}
}
// Write output coverage for unfinished calls.
if (running > 0) {
for (int i = 0; i < kMaxThreads; i++) {
thread_t* th = &threads[i];
if (th->executing) {
if (flag_coverage)
cover_collect(&th->cov);
write_call_output(th, false);
}
}
}
}
#if SYZ_HAVE_CLOSE_FDS
close_fds();
#endif
if (!colliding && !collide) {
write_extra_output();
// Check for new extra coverage in small intervals to avoid situation
// that we were killed on timeout before we write any.
// Check for extra coverage is very cheap, effectively a memory load.
const uint64 kSleepMs = 100;
for (uint64 i = 0; i < prog_extra_cover_timeout / kSleepMs; i++) {
sleep_ms(kSleepMs);
write_extra_output();
}
}
if (flag_collide && !flag_fault && !colliding && !collide) {
debug("enabling collider\n");
collide = colliding = true;
goto retry;
}
}
thread_t* schedule_call(int call_index, int call_num, bool colliding, uint64 copyout_index, uint64 num_args, uint64* args, uint64* pos)
{
// Find a spare thread to execute the call.
int i = 0;
for (; i < kMaxThreads; i++) {
thread_t* th = &threads[i];
if (!th->created)
thread_create(th, i);
if (event_isset(&th->done)) {
if (th->executing)
handle_completion(th);
break;
}
}
if (i == kMaxThreads)
exitf("out of threads");
thread_t* th = &threads[i];
if (event_isset(&th->ready) || !event_isset(&th->done) || th->executing)
fail("bad thread state in schedule: ready=%d done=%d executing=%d",
event_isset(&th->ready), event_isset(&th->done), th->executing);
last_scheduled = th;
th->colliding = colliding;
th->copyout_pos = pos;
th->copyout_index = copyout_index;
event_reset(&th->done);
th->executing = true;
th->call_index = call_index;
th->call_num = call_num;
th->num_args = num_args;
for (int i = 0; i < kMaxArgs; i++)
th->args[i] = args[i];
event_set(&th->ready);
running++;
return th;
}
#if SYZ_EXECUTOR_USES_SHMEM
template <typename cover_data_t>
void write_coverage_signal(cover_t* cov, uint32* signal_count_pos, uint32* cover_count_pos)
{
// Write out feedback signals.
// Currently it is code edges computed as xor of two subsequent basic block PCs.
cover_data_t* cover_data = ((cover_data_t*)cov->data) + 1;
uint32 nsig = 0;
cover_data_t prev = 0;
for (uint32 i = 0; i < cov->size; i++) {
cover_data_t pc = cover_data[i];
if (!cover_check(pc)) {
debug("got bad pc: 0x%llx\n", (uint64)pc);
doexit(0);
}
cover_data_t sig = pc ^ prev;
prev = hash(pc);
if (dedup(sig))
continue;
write_output(sig);
nsig++;
}
// Write out number of signals.
*signal_count_pos = nsig;
if (!flag_collect_cover)
return;
// Write out real coverage (basic block PCs).
uint32 cover_size = cov->size;
if (flag_dedup_cover) {
cover_data_t* end = cover_data + cover_size;
cover_unprotect(cov);
std::sort(cover_data, end);
cover_size = std::unique(cover_data, end) - cover_data;
cover_protect(cov);
}
// Truncate PCs to uint32 assuming that they fit into 32-bits.
// True for x86_64 and arm64 without KASLR.
for (uint32 i = 0; i < cover_size; i++)
write_output(cover_data[i]);
*cover_count_pos = cover_size;
}
#endif
void handle_completion(thread_t* th)
{
if (event_isset(&th->ready) || !event_isset(&th->done) || !th->executing)
fail("bad thread state in completion: ready=%d done=%d executing=%d",
event_isset(&th->ready), event_isset(&th->done), th->executing);
if (th->res != (intptr_t)-1)
copyout_call_results(th);
if (!collide && !th->colliding) {
write_call_output(th, true);
write_extra_output();
}
th->executing = false;
running--;
if (running < 0) {
// This fires periodically for the past 2 years (see issue #502).
fprintf(stderr, "running=%d collide=%d completed=%d flag_threaded=%d flag_collide=%d current=%d\n",
running, collide, completed, flag_threaded, flag_collide, th->id);
for (int i = 0; i < kMaxThreads; i++) {
thread_t* th1 = &threads[i];
fprintf(stderr, "th #%2d: created=%d executing=%d colliding=%d"
" ready=%d done=%d call_index=%d res=%lld reserrno=%d\n",
i, th1->created, th1->executing, th1->colliding,
event_isset(&th1->ready), event_isset(&th1->done),
th1->call_index, (uint64)th1->res, th1->reserrno);
}
fail("running = %d", running);
}
}
void copyout_call_results(thread_t* th)
{
if (th->copyout_index != no_copyout) {
if (th->copyout_index >= kMaxCommands)
fail("result idx %lld overflows kMaxCommands", th->copyout_index);
results[th->copyout_index].executed = true;
results[th->copyout_index].val = th->res;
}
for (bool done = false; !done;) {
uint64 instr = read_input(&th->copyout_pos);
switch (instr) {
case instr_copyout: {
uint64 index = read_input(&th->copyout_pos);
if (index >= kMaxCommands)
fail("result idx %lld overflows kMaxCommands", index);
char* addr = (char*)read_input(&th->copyout_pos);
uint64 size = read_input(&th->copyout_pos);
uint64 val = 0;
if (copyout(addr, size, &val)) {
results[index].executed = true;
results[index].val = val;
}
debug_verbose("copyout 0x%llx from %p\n", val, addr);
break;
}
default:
done = true;
break;
}
}
}
void write_call_output(thread_t* th, bool finished)
{
uint32 reserrno = 999;
const bool blocked = finished && th != last_scheduled;
uint32 call_flags = call_flag_executed | (blocked ? call_flag_blocked : 0);
if (finished) {
reserrno = th->res != -1 ? 0 : th->reserrno;
call_flags |= call_flag_finished |
(th->fault_injected ? call_flag_fault_injected : 0);
}
#if SYZ_EXECUTOR_USES_SHMEM
write_output(th->call_index);
write_output(th->call_num);
write_output(reserrno);
write_output(call_flags);
uint32* signal_count_pos = write_output(0); // filled in later
uint32* cover_count_pos = write_output(0); // filled in later
uint32* comps_count_pos = write_output(0); // filled in later
if (flag_comparisons) {
// Collect only the comparisons
uint32 ncomps = th->cov.size;
kcov_comparison_t* start = (kcov_comparison_t*)(th->cov.data + sizeof(uint64));
kcov_comparison_t* end = start + ncomps;
if ((char*)end > th->cov.data_end)
fail("too many comparisons %u", ncomps);
cover_unprotect(&th->cov);
std::sort(start, end);
ncomps = std::unique(start, end) - start;
cover_protect(&th->cov);
uint32 comps_size = 0;
for (uint32 i = 0; i < ncomps; ++i) {
if (start[i].ignore())
continue;
comps_size++;
start[i].write();
}
// Write out number of comparisons.
*comps_count_pos = comps_size;
} else if (flag_coverage) {
if (is_kernel_64_bit)
write_coverage_signal<uint64>(&th->cov, signal_count_pos, cover_count_pos);
else
write_coverage_signal<uint32>(&th->cov, signal_count_pos, cover_count_pos);
}