// https://syzkaller.appspot.com/bug?id=3948bb34095f7acf6a3464667cb9342249cbe302 // autogenerated by syzkaller (https://github.com/google/syzkaller) #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static unsigned long long procid; static void sleep_ms(uint64_t ms) { usleep(ms * 1000); } static uint64_t current_time_ms(void) { struct timespec ts; if (clock_gettime(CLOCK_MONOTONIC, &ts)) exit(1); return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000; } static void thread_start(void* (*fn)(void*), void* arg) { pthread_t th; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setstacksize(&attr, 128 << 10); int i = 0; for (; i < 100; i++) { if (pthread_create(&th, &attr, fn, arg) == 0) { pthread_attr_destroy(&attr); return; } if (errno == EAGAIN) { usleep(50); continue; } break; } exit(1); } typedef struct { int state; } event_t; static void event_init(event_t* ev) { ev->state = 0; } static void event_reset(event_t* ev) { ev->state = 0; } static void event_set(event_t* ev) { if (ev->state) exit(1); __atomic_store_n(&ev->state, 1, __ATOMIC_RELEASE); syscall(SYS_futex, &ev->state, FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1000000); } static void event_wait(event_t* ev) { while (!__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE)) syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 0, 0); } static int event_isset(event_t* ev) { return __atomic_load_n(&ev->state, __ATOMIC_ACQUIRE); } static int event_timedwait(event_t* ev, uint64_t timeout) { uint64_t start = current_time_ms(); uint64_t now = start; for (;;) { uint64_t remain = timeout - (now - start); struct timespec ts; ts.tv_sec = remain / 1000; ts.tv_nsec = (remain % 1000) * 1000 * 1000; syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 0, &ts); if (__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE)) return 1; now = current_time_ms(); if (now - start > timeout) return 0; } } static bool write_file(const char* file, const char* what, ...) { char buf[1024]; va_list args; va_start(args, what); vsnprintf(buf, sizeof(buf), what, args); va_end(args); buf[sizeof(buf) - 1] = 0; int len = strlen(buf); int fd = open(file, O_WRONLY | O_CLOEXEC); if (fd == -1) return false; if (write(fd, buf, len) != len) { int err = errno; close(fd); errno = err; return false; } close(fd); return true; } struct nlmsg { char* pos; int nesting; struct nlattr* nested[8]; char buf[4096]; }; static void netlink_init(struct nlmsg* nlmsg, int typ, int flags, const void* data, int size) { memset(nlmsg, 0, sizeof(*nlmsg)); struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg->buf; hdr->nlmsg_type = typ; hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags; memcpy(hdr + 1, data, size); nlmsg->pos = (char*)(hdr + 1) + NLMSG_ALIGN(size); } static void netlink_attr(struct nlmsg* nlmsg, int typ, const void* data, int size) { struct nlattr* attr = (struct nlattr*)nlmsg->pos; attr->nla_len = sizeof(*attr) + size; attr->nla_type = typ; if (size > 0) memcpy(attr + 1, data, size); nlmsg->pos += NLMSG_ALIGN(attr->nla_len); } static int netlink_send_ext(struct nlmsg* nlmsg, int sock, uint16_t reply_type, int* reply_len) { if (nlmsg->pos > nlmsg->buf + sizeof(nlmsg->buf) || nlmsg->nesting) exit(1); struct nlmsghdr* hdr = (struct nlmsghdr*)nlmsg->buf; hdr->nlmsg_len = nlmsg->pos - nlmsg->buf; struct sockaddr_nl addr; memset(&addr, 0, sizeof(addr)); addr.nl_family = AF_NETLINK; unsigned n = sendto(sock, nlmsg->buf, hdr->nlmsg_len, 0, (struct sockaddr*)&addr, sizeof(addr)); if (n != hdr->nlmsg_len) exit(1); n = recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0); if (reply_len) *reply_len = 0; if (hdr->nlmsg_type == NLMSG_DONE) return 0; if (n < sizeof(struct nlmsghdr)) exit(1); if (reply_len && hdr->nlmsg_type == reply_type) { *reply_len = n; return 0; } if (n < sizeof(struct nlmsghdr) + sizeof(struct nlmsgerr)) exit(1); if (hdr->nlmsg_type != NLMSG_ERROR) exit(1); return ((struct nlmsgerr*)(hdr + 1))->error; } static int netlink_send(struct nlmsg* nlmsg, int sock) { return netlink_send_ext(nlmsg, sock, 0, NULL); } static int netlink_query_family_id(struct nlmsg* nlmsg, int sock, const char* family_name) { struct genlmsghdr genlhdr; memset(&genlhdr, 0, sizeof(genlhdr)); genlhdr.cmd = CTRL_CMD_GETFAMILY; netlink_init(nlmsg, GENL_ID_CTRL, 0, &genlhdr, sizeof(genlhdr)); netlink_attr(nlmsg, CTRL_ATTR_FAMILY_NAME, family_name, strnlen(family_name, GENL_NAMSIZ - 1) + 1); int n = 0; int err = netlink_send_ext(nlmsg, sock, GENL_ID_CTRL, &n); if (err < 0) { return -1; } uint16_t id = 0; struct nlattr* attr = (struct nlattr*)(nlmsg->buf + NLMSG_HDRLEN + NLMSG_ALIGN(sizeof(genlhdr))); for (; (char*)attr < nlmsg->buf + n; attr = (struct nlattr*)((char*)attr + NLMSG_ALIGN(attr->nla_len))) { if (attr->nla_type == CTRL_ATTR_FAMILY_ID) { id = *(uint16_t*)(attr + 1); break; } } if (!id) { return -1; } recv(sock, nlmsg->buf, sizeof(nlmsg->buf), 0); return id; } #define WIFI_INITIAL_DEVICE_COUNT 2 #define WIFI_MAC_BASE \ { \ 0x08, 0x02, 0x11, 0x00, 0x00, 0x00 \ } #define WIFI_IBSS_BSSID \ { \ 0x50, 0x50, 0x50, 0x50, 0x50, 0x50 \ } #define WIFI_IBSS_SSID \ { \ 0x10, 0x10, 0x10, 0x10, 0x10, 0x10 \ } #define WIFI_DEFAULT_FREQUENCY 2412 #define WIFI_DEFAULT_SIGNAL 0 #define WIFI_DEFAULT_RX_RATE 1 #define HWSIM_CMD_REGISTER 1 #define HWSIM_CMD_FRAME 2 #define HWSIM_CMD_NEW_RADIO 4 #define HWSIM_ATTR_SUPPORT_P2P_DEVICE 14 #define HWSIM_ATTR_PERM_ADDR 22 #define IF_OPER_UP 6 struct join_ibss_props { int wiphy_freq; bool wiphy_freq_fixed; uint8_t* mac; uint8_t* ssid; int ssid_len; }; static int set_interface_state(const char* interface_name, int on) { struct ifreq ifr; int sock = socket(AF_INET, SOCK_DGRAM, 0); if (sock < 0) { return -1; } memset(&ifr, 0, sizeof(ifr)); strcpy(ifr.ifr_name, interface_name); int ret = ioctl(sock, SIOCGIFFLAGS, &ifr); if (ret < 0) { close(sock); return -1; } if (on) ifr.ifr_flags |= IFF_UP; else ifr.ifr_flags &= ~IFF_UP; ret = ioctl(sock, SIOCSIFFLAGS, &ifr); close(sock); if (ret < 0) { return -1; } return 0; } static int nl80211_set_interface(struct nlmsg* nlmsg, int sock, int nl80211_family, uint32_t ifindex, uint32_t iftype) { struct genlmsghdr genlhdr; memset(&genlhdr, 0, sizeof(genlhdr)); genlhdr.cmd = NL80211_CMD_SET_INTERFACE; netlink_init(nlmsg, nl80211_family, 0, &genlhdr, sizeof(genlhdr)); netlink_attr(nlmsg, NL80211_ATTR_IFINDEX, &ifindex, sizeof(ifindex)); netlink_attr(nlmsg, NL80211_ATTR_IFTYPE, &iftype, sizeof(iftype)); int err = netlink_send(nlmsg, sock); if (err < 0) { return -1; } return 0; } static int nl80211_join_ibss(struct nlmsg* nlmsg, int sock, int nl80211_family, uint32_t ifindex, struct join_ibss_props* props) { struct genlmsghdr genlhdr; memset(&genlhdr, 0, sizeof(genlhdr)); genlhdr.cmd = NL80211_CMD_JOIN_IBSS; netlink_init(nlmsg, nl80211_family, 0, &genlhdr, sizeof(genlhdr)); netlink_attr(nlmsg, NL80211_ATTR_IFINDEX, &ifindex, sizeof(ifindex)); netlink_attr(nlmsg, NL80211_ATTR_SSID, props->ssid, props->ssid_len); netlink_attr(nlmsg, NL80211_ATTR_WIPHY_FREQ, &(props->wiphy_freq), sizeof(props->wiphy_freq)); if (props->mac) netlink_attr(nlmsg, NL80211_ATTR_MAC, props->mac, ETH_ALEN); if (props->wiphy_freq_fixed) netlink_attr(nlmsg, NL80211_ATTR_FREQ_FIXED, NULL, 0); int err = netlink_send(nlmsg, sock); if (err < 0) { return -1; } return 0; } static int get_ifla_operstate(struct nlmsg* nlmsg, int ifindex) { struct ifinfomsg info; memset(&info, 0, sizeof(info)); info.ifi_family = AF_UNSPEC; info.ifi_index = ifindex; int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE); if (sock == -1) { return -1; } netlink_init(nlmsg, RTM_GETLINK, 0, &info, sizeof(info)); int n; int err = netlink_send_ext(nlmsg, sock, RTM_NEWLINK, &n); close(sock); if (err) { return -1; } struct rtattr* attr = IFLA_RTA(NLMSG_DATA(nlmsg->buf)); for (; RTA_OK(attr, n); attr = RTA_NEXT(attr, n)) { if (attr->rta_type == IFLA_OPERSTATE) return *((int32_t*)RTA_DATA(attr)); } return -1; } static int await_ifla_operstate(struct nlmsg* nlmsg, char* interface, int operstate) { int ifindex = if_nametoindex(interface); while (true) { usleep(1000); int ret = get_ifla_operstate(nlmsg, ifindex); if (ret < 0) return ret; if (ret == operstate) return 0; } return 0; } static int nl80211_setup_ibss_interface(struct nlmsg* nlmsg, int sock, int nl80211_family_id, char* interface, struct join_ibss_props* ibss_props) { int ifindex = if_nametoindex(interface); if (ifindex == 0) { return -1; } int ret = nl80211_set_interface(nlmsg, sock, nl80211_family_id, ifindex, NL80211_IFTYPE_ADHOC); if (ret < 0) { return -1; } ret = set_interface_state(interface, 1); if (ret < 0) { return -1; } ret = nl80211_join_ibss(nlmsg, sock, nl80211_family_id, ifindex, ibss_props); if (ret < 0) { return -1; } return 0; } static long syz_genetlink_get_family_id(volatile long name) { struct nlmsg nlmsg_tmp; int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC); if (fd == -1) { return -1; } int ret = netlink_query_family_id(&nlmsg_tmp, fd, (char*)name); close(fd); if (ret < 0) { return -1; } return ret; } static void kill_and_wait(int pid, int* status) { kill(-pid, SIGKILL); kill(pid, SIGKILL); for (int i = 0; i < 100; i++) { if (waitpid(-1, status, WNOHANG | __WALL) == pid) return; usleep(1000); } DIR* dir = opendir("/sys/fs/fuse/connections"); if (dir) { for (;;) { struct dirent* ent = readdir(dir); if (!ent) break; if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0) continue; char abort[300]; snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name); int fd = open(abort, O_WRONLY); if (fd == -1) { continue; } if (write(fd, abort, 1) < 0) { } close(fd); } closedir(dir); } else { } while (waitpid(-1, status, __WALL) != pid) { } } static void setup_test() { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); setpgrp(); write_file("/proc/self/oom_score_adj", "1000"); } #define WIFI_MAX_SSID_LEN 32 #define WIFI_JOIN_IBSS_NO_SCAN 0 #define WIFI_JOIN_IBSS_BG_SCAN 1 #define WIFI_JOIN_IBSS_BG_NO_SCAN 2 static long syz_80211_join_ibss(volatile long a0, volatile long a1, volatile long a2, volatile long a3) { char* interface = (char*)a0; uint8_t* ssid = (uint8_t*)a1; int ssid_len = (int)a2; int mode = (int)a3; struct nlmsg tmp_msg; uint8_t bssid[ETH_ALEN] = WIFI_IBSS_BSSID; if (ssid_len < 0 || ssid_len > WIFI_MAX_SSID_LEN) { return -1; } if (mode < 0 || mode > WIFI_JOIN_IBSS_BG_NO_SCAN) { return -1; } int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC); if (sock < 0) { return -1; } int nl80211_family_id = netlink_query_family_id(&tmp_msg, sock, "nl80211"); struct join_ibss_props ibss_props = { .wiphy_freq = WIFI_DEFAULT_FREQUENCY, .wiphy_freq_fixed = (mode == WIFI_JOIN_IBSS_NO_SCAN || mode == WIFI_JOIN_IBSS_BG_NO_SCAN), .mac = bssid, .ssid = ssid, .ssid_len = ssid_len}; int ret = nl80211_setup_ibss_interface(&tmp_msg, sock, nl80211_family_id, interface, &ibss_props); close(sock); if (ret < 0) { return -1; } if (mode == WIFI_JOIN_IBSS_NO_SCAN) { ret = await_ifla_operstate(&tmp_msg, interface, IF_OPER_UP); if (ret < 0) { return -1; } } return 0; } struct thread_t { int created, call; event_t ready, done; }; static struct thread_t threads[16]; static void execute_call(int call); static int running; static void* thr(void* arg) { struct thread_t* th = (struct thread_t*)arg; for (;;) { event_wait(&th->ready); event_reset(&th->ready); execute_call(th->call); __atomic_fetch_sub(&running, 1, __ATOMIC_RELAXED); event_set(&th->done); } return 0; } static void execute_one(void) { int i, call, thread; int collide = 0; again: for (call = 0; call < 9; call++) { for (thread = 0; thread < (int)(sizeof(threads) / sizeof(threads[0])); thread++) { struct thread_t* th = &threads[thread]; if (!th->created) { th->created = 1; event_init(&th->ready); event_init(&th->done); event_set(&th->done); thread_start(thr, th); } if (!event_isset(&th->done)) continue; event_reset(&th->done); th->call = call; __atomic_fetch_add(&running, 1, __ATOMIC_RELAXED); event_set(&th->ready); if (collide && (call % 2) == 0) break; event_timedwait(&th->done, 45); break; } } for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++) sleep_ms(1); if (!collide) { collide = 1; goto again; } } static void execute_one(void); #define WAIT_FLAGS __WALL static void loop(void) { int iter = 0; for (;; iter++) { int pid = fork(); if (pid < 0) exit(1); if (pid == 0) { setup_test(); execute_one(); exit(0); } int status = 0; uint64_t start = current_time_ms(); for (;;) { if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid) break; sleep_ms(1); if (current_time_ms() - start < 5 * 1000) continue; kill_and_wait(pid, &status); break; } } } uint64_t r[6] = { 0xffffffffffffffff, 0x0, 0x0, 0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff}; void execute_call(int call) { intptr_t res = 0; switch (call) { case 0: res = syscall(__NR_socket, 0x10ul, 3ul, 0x10); if (res != -1) r[0] = res; break; case 1: memcpy((void*)0x20000000, "nl80211\000", 8); res = -1; res = syz_genetlink_get_family_id(0x20000000); if (res != -1) r[1] = res; break; case 2: memcpy((void*)0x20000700, "wlan0\000\000\000\000\000\000\000\000\000\000\000", 16); res = syscall(__NR_ioctl, r[0], 0x8933, 0x20000700ul); if (res != -1) r[2] = *(uint32_t*)0x20000710; break; case 3: *(uint64_t*)0x20000340 = 0; *(uint32_t*)0x20000348 = 0; *(uint64_t*)0x20000350 = 0x20000300; *(uint64_t*)0x20000300 = 0x20000240; *(uint32_t*)0x20000240 = 0x24; *(uint16_t*)0x20000244 = r[1]; *(uint16_t*)0x20000246 = 5; *(uint32_t*)0x20000248 = 0; *(uint32_t*)0x2000024c = 0; *(uint8_t*)0x20000250 = 6; *(uint8_t*)0x20000251 = 0; *(uint16_t*)0x20000252 = 0; *(uint16_t*)0x20000254 = 8; *(uint16_t*)0x20000256 = 3; *(uint32_t*)0x20000258 = r[2]; *(uint16_t*)0x2000025c = 8; *(uint16_t*)0x2000025e = 5; *(uint32_t*)0x20000260 = 9; *(uint64_t*)0x20000308 = 0x24; *(uint64_t*)0x20000358 = 1; *(uint64_t*)0x20000360 = 0; *(uint64_t*)0x20000368 = 0; *(uint32_t*)0x20000370 = 0; syscall(__NR_sendmsg, r[0], 0x20000340ul, 0ul); break; case 4: memcpy((void*)0x20000040, "wlan0\000", 6); syz_80211_join_ibss(0x20000040, 0, 0, 0); break; case 5: res = syscall(__NR_socket, 0x10ul, 3ul, 0x10); if (res != -1) r[3] = res; break; case 6: memcpy((void*)0x20000200, "nl80211\000", 8); res = -1; res = syz_genetlink_get_family_id(0x20000200); if (res != -1) r[4] = res; break; case 7: memcpy((void*)0x20000700, "wlan0\000\000\000\000\000\000\000\000\000\000\000", 16); res = syscall(__NR_ioctl, r[3], 0x8933, 0x20000700ul); if (res != -1) r[5] = *(uint32_t*)0x20000710; break; case 8: *(uint64_t*)0x20000340 = 0; *(uint32_t*)0x20000348 = 0; *(uint64_t*)0x20000350 = 0x20000300; *(uint64_t*)0x20000300 = 0x20000380; memcpy((void*)0x20000380, "\x00\x03\x00\x00", 4); *(uint16_t*)0x20000384 = r[4]; memcpy((void*)0x20000386, "\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0f\x00" "\x00\x00\x08\x00\x03\x00", 18); *(uint32_t*)0x20000398 = r[5]; memcpy( (void*)0x2000039c, "\x28\x00\x0e\x00\x80\x00\x00\x00\xff\xff\xff\xff\xff\xff\x08\x02\x11" "\x00\x00\x01\x4c\x88\xe8\xeb\x7e\x00\x00\x00\x00\x00\x00\x00\x00\x00" "\x00\x00\x64\x00\xff\xff\x08\x00\x26\x00\x6c\x09\x00\x00\x08\x00\x0c" "\x00\x64\x00\x00\x00\x08\x00\x0d\x00\x00\x00\x00\x00\x0a\x00\x34\x00" "\x02\x02\x02\x02\x02\x02\x00\x00\x08\x00\x35\x00\x00\x00\x00\x00\x90" "\x02\x0f\x00\x04\x4e\x79\xc1\x99\xe8\x3b\xed\x43\x6d\x9b\x18\xd6\x35" "\xd7\xd6\xe8\x00\x08\x00\x00\x88\x54\x41\x3f\x64\xd1\x7b\x8d\x7a\x90" "\x41\xea\x1a\xa6\xcb\x32\x8e\x4e\xae\x74\xed\xc1\xe0\xad\x5b\x56\x00" "\x31\x9a\x0c\xf9\x6d\x64\xa3\x28\xee\xca\xfa\xc1\x12\xed\x3e\xc8\x84" "\xa1\x53\x1d\xfd\xf1\x7a\x1c\xbe\x07\xe1\x3a\xd5\x79\x11\xd1\x2d\x26" "\x9b\x02\x2c\xcf\x8f\xf9\xaf\x66\xb4\x1d\x84\xa1\xf4\x7c\xd1\x6e\xce" "\xac\xcf\x5e\xf9\x15\x9b\x14\xc6\xd0\x25\xae\xa1\x2d\xba\xe5\x03\xb9" "\x48\x22\xfd\x6a\x1c\x7b\xbb\x4c\x9d\x1e\xff\xa4\x6a\x99\xc6\x02\x5a" "\xba\x12\x6a\xb4\xd7\x43\x3b\x72\x2b\x8c\xf4\x0f\xaa\xb9\x1f\x78\x6c" "\x32\x81\x3e\xc3\x1c\xbb\xec\xee\xeb\xe4\x4f\xb3\x52\x7d\x98\x35\x6b" "\x7c\xef\x74\x53\xa6\xd0\xbc\x7c\x65\x73\xe1\xe9\x31\x55\x7e\x85\x94" "\x57\x2f\xe5\x20\xd0\xb3\x90\x3b\xd7\xe8\x5e\xc4\xab\xc6\x4e\x96\x4b" "\x56\x55\xb2\x40\xa4\xe6\x02\x0c\x7a\x9f\x72\xb1\x6a\xf0\xfb\xcd\xcb" "\x35\x4e\x91\xc6\x9c\x1a\x6b\xa7\x57\x64\x92\x63\xf8\xb0\xbc\x97\xce" "\x3f\xfc\x1f\xff\xa6\x04\x7b\xb4\xa1\x8a\xad\x45\xa0\xfa\x6f\x1c\xf4" "\x40\x8c\x8d\xf7\x9b\xce\xdd\xae\xff\xb0\x50\x1f\x61\x5f\xeb\x70\x80" "\x1a\xac\x79\xa1\xb3\xb7\x40\x01\x06\x6b\xfe\x7b\x65\x2c\x5b\xa9\xe6" "\xdf\x56\x06\x10\xaf\xa7\xb2\xb0\xae\x89\xd8\x16\x7e\xf9\x5c\xab\x5f" "\x20\x73\x20\x67\x98\x08\x9f\x72\x5a\x5d\x9f\x20\x7a\x14\x09\x90\x61" "\x12\xda\x7e\x52\xb9\x0d\x5e\xa3\x45\x37\xd6\xd6\xce\x24\xa2\xdb\x63" "\x14\x41\xbe\x1e\x6d\x63\x23\xd6\x16\x55\xd4\x15\x6b\x50\x6f\xdb\xe3" "\xf6\xc9\x81\x35\x28\xa9\x50\xdf\x8a\x4c\x2a\x6a\x00\x00\x00\x00\x00" "\x00\x00\x00\x00\x00\x00\x00\x00", 467); *(uint64_t*)0x20000308 = 0x300; *(uint64_t*)0x20000358 = 1; *(uint64_t*)0x20000360 = 0; *(uint64_t*)0x20000368 = 0; *(uint32_t*)0x20000370 = 0; syscall(__NR_sendmsg, r[3], 0x20000340ul, 0ul); break; } } int main(void) { syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul); syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); for (procid = 0; procid < 6; procid++) { if (fork() == 0) { loop(); } } sleep(1000000); return 0; }