diff --git a/Makefile b/Makefile
index 3a0f0100232c..a70623dd4a52 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,31 @@
+ifeq ("$(origin V)", "command line")
+	BUILD_VERBOSE = $(V)
+else
+	BUILD_VERBOSE = 0
+endif
+ifndef BUILD_VERBOSE
+	BUILD_VERBOSE = 0
+endif
+
+ifeq ($(BUILD_VERBOSE),1)
+	Q =
+else
+	Q = @
+endif
+
+MAKEOPTS = --no-print-directory Q=$(Q)
+
+SUBDIRS = src
+default:
+	$(Q)$(MAKE) $(MAKEOPTS) -C $(SUBDIRS)
+
+clean:
+	$(Q)$(MAKE) $(MAKEOPTS) -C $(SUBDIRS) clean
+
 all:
 	@echo "Please read README.md"
 
 shellcheck:
 	shellcheck -x -f gcc check new common/* tests/*/[0-9]*[0-9]
 
-.PHONY: all shellcheck
+.PHONY: all shellcheck clean
diff --git a/src/.gitignore b/src/.gitignore
new file mode 100644
index 000000000000..f543ddb9280f
--- /dev/null
+++ b/src/.gitignore
@@ -0,0 +1 @@
+sg-001
diff --git a/src/Makefile b/src/Makefile
new file mode 100644
index 000000000000..d05b625cc7f8
--- /dev/null
+++ b/src/Makefile
@@ -0,0 +1,16 @@
+CC = gcc
+CFLAGS = -O2
+
+TARGETS = sg-001
+
+FILES = $(TARGETS:=.c)
+
+all: $(TARGETS)
+
+$(TARGETS): $(FILES)
+	@echo "    [CC]    $@"
+	$(Q)$(CC) $@.c -o $@ $(CFLAGS)
+
+clean:
+	@echo "    [CLEAN]  $(notdir $(CURDIR))"
+	$(Q)rm -f $(TARGETS) *.o
diff --git a/src/sg-001.c b/src/sg-001.c
new file mode 100644
index 000000000000..1dabba7d5ae8
--- /dev/null
+++ b/src/sg-001.c
@@ -0,0 +1,438 @@
+// autogenerated by syzkaller (http://github.com/google/syzkaller)
+
+#ifndef __NR_read
+#define __NR_read 0
+#endif
+#ifndef __NR_mmap
+#define __NR_mmap 9
+#endif
+#ifndef __NR_syz_open_dev
+#define __NR_syz_open_dev 1000002
+#endif
+#ifndef __NR_write
+#define __NR_write 1
+#endif
+
+#define _GNU_SOURCE
+
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
+#include <sys/prctl.h>
+#include <sys/resource.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include <arpa/inet.h>
+#include <linux/capability.h>
+#include <linux/if.h>
+#include <linux/if_ether.h>
+#include <linux/if_tun.h>
+#include <linux/ip.h>
+#include <linux/kvm.h>
+#include <linux/sched.h>
+#include <linux/tcp.h>
+#include <net/if_arp.h>
+
+#include <assert.h>
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <pthread.h>
+#include <setjmp.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+const int kFailStatus = 67;
+const int kErrorStatus = 68;
+const int kRetryStatus = 69;
+
+const char *dev_sg;
+
+__attribute__((noreturn)) void doexit(int status)
+{
+  volatile unsigned i;
+  syscall(__NR_exit_group, status);
+  for (i = 0;; i++) {
+  }
+}
+
+__attribute__((noreturn)) void fail(const char* msg, ...)
+{
+  int e = errno;
+  fflush(stdout);
+  va_list args;
+  va_start(args, msg);
+  vfprintf(stderr, msg, args);
+  va_end(args);
+  fprintf(stderr, " (errno %d)\n", e);
+  doexit((e == ENOMEM || e == EAGAIN) ? kRetryStatus : kFailStatus);
+}
+
+__attribute__((noreturn)) void exitf(const char* msg, ...)
+{
+  int e = errno;
+  fflush(stdout);
+  va_list args;
+  va_start(args, msg);
+  vfprintf(stderr, msg, args);
+  va_end(args);
+  fprintf(stderr, " (errno %d)\n", e);
+  doexit(kRetryStatus);
+}
+
+static int flag_debug;
+
+void debug(const char* msg, ...)
+{
+  if (!flag_debug)
+    return;
+  va_list args;
+  va_start(args, msg);
+  vfprintf(stdout, msg, args);
+  va_end(args);
+  fflush(stdout);
+}
+
+__thread int skip_segv;
+__thread jmp_buf segv_env;
+
+static void segv_handler(int sig, siginfo_t* info, void* uctx)
+{
+  uintptr_t addr = (uintptr_t)info->si_addr;
+  const uintptr_t prog_start = 1 << 20;
+  const uintptr_t prog_end = 100 << 20;
+  if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) &&
+      (addr < prog_start || addr > prog_end)) {
+    debug("SIGSEGV on %p, skipping\n", addr);
+    _longjmp(segv_env, 1);
+  }
+  debug("SIGSEGV on %p, exiting\n", addr);
+  doexit(sig);
+  for (;;) {
+  }
+}
+
+static void install_segv_handler()
+{
+  struct sigaction sa;
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_sigaction = segv_handler;
+  sa.sa_flags = SA_NODEFER | SA_SIGINFO;
+  sigaction(SIGSEGV, &sa, NULL);
+  sigaction(SIGBUS, &sa, NULL);
+}
+
+#define NONFAILING(...)                                                \
+  {                                                                    \
+    __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST);               \
+    if (_setjmp(segv_env) == 0) {                                      \
+      __VA_ARGS__;                                                     \
+    }                                                                  \
+    __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST);               \
+  }
+
+#define BITMASK_LEN(type, bf_len) (type)((1ull << (bf_len)) - 1)
+
+#define BITMASK_LEN_OFF(type, bf_off, bf_len)                          \
+  (type)(BITMASK_LEN(type, (bf_len)) << (bf_off))
+
+#define STORE_BY_BITMASK(type, addr, val, bf_off, bf_len)              \
+  if ((bf_off) == 0 && (bf_len) == 0) {                                \
+    *(type*)(addr) = (type)(val);                                      \
+  } else {                                                             \
+    type new_val = *(type*)(addr);                                     \
+    new_val &= ~BITMASK_LEN_OFF(type, (bf_off), (bf_len));             \
+    new_val |= ((type)(val)&BITMASK_LEN(type, (bf_len))) << (bf_off);  \
+    *(type*)(addr) = new_val;                                          \
+  }
+
+struct csum_inet {
+  uint32_t acc;
+};
+
+void csum_inet_init(struct csum_inet* csum)
+{
+  csum->acc = 0;
+}
+
+void csum_inet_update(struct csum_inet* csum, const uint8_t* data,
+                      size_t length)
+{
+  if (length == 0)
+    return;
+
+  size_t i;
+  for (i = 0; i < length - 1; i += 2)
+    csum->acc += *(uint16_t*)&data[i];
+
+  if (length & 1)
+    csum->acc += (uint16_t)data[length - 1];
+
+  while (csum->acc > 0xffff)
+    csum->acc = (csum->acc & 0xffff) + (csum->acc >> 16);
+}
+
+uint16_t csum_inet_digest(struct csum_inet* csum)
+{
+  return ~csum->acc;
+}
+
+static uintptr_t syz_open_dev(uintptr_t a0, uintptr_t a1, uintptr_t a2)
+{
+  if (a0 == 0xc || a0 == 0xb) {
+    char buf[128];
+    sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block",
+            (uint8_t)a1, (uint8_t)a2);
+    return open(buf, O_RDWR, 0);
+  } else {
+    char buf[1024];
+    char* hash;
+    NONFAILING(strncpy(buf, (char*)a0, sizeof(buf)));
+    buf[sizeof(buf) - 1] = 0;
+    while ((hash = strchr(buf, '#'))) {
+      *hash = '0' + (char)(a1 % 10);
+      a1 /= 10;
+    }
+    return open(buf, a2, 0);
+  }
+}
+
+static uintptr_t execute_syscall(int nr, uintptr_t a0, uintptr_t a1,
+                                 uintptr_t a2, uintptr_t a3,
+                                 uintptr_t a4, uintptr_t a5,
+                                 uintptr_t a6, uintptr_t a7,
+                                 uintptr_t a8)
+{
+  switch (nr) {
+  default:
+    return syscall(nr, a0, a1, a2, a3, a4, a5);
+  case __NR_syz_open_dev:
+    return syz_open_dev(a0, a1, a2);
+  }
+}
+
+static void setup_main_process()
+{
+  struct sigaction sa;
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_handler = SIG_IGN;
+  syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8);
+  syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8);
+  install_segv_handler();
+
+  char tmpdir_template[] = "./syzkaller.XXXXXX";
+  char* tmpdir = mkdtemp(tmpdir_template);
+  if (!tmpdir)
+    fail("failed to mkdtemp");
+  if (chmod(tmpdir, 0777))
+    fail("failed to chmod");
+  if (chdir(tmpdir))
+    fail("failed to chdir");
+}
+
+static void loop();
+
+static void sandbox_common()
+{
+  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
+  setpgrp();
+  setsid();
+
+  struct rlimit rlim;
+  rlim.rlim_cur = rlim.rlim_max = 128 << 20;
+  setrlimit(RLIMIT_AS, &rlim);
+  rlim.rlim_cur = rlim.rlim_max = 1 << 20;
+  setrlimit(RLIMIT_FSIZE, &rlim);
+  rlim.rlim_cur = rlim.rlim_max = 1 << 20;
+  setrlimit(RLIMIT_STACK, &rlim);
+  rlim.rlim_cur = rlim.rlim_max = 0;
+  setrlimit(RLIMIT_CORE, &rlim);
+
+  unshare(CLONE_NEWNS);
+  unshare(CLONE_NEWIPC);
+  unshare(CLONE_IO);
+}
+
+static int do_sandbox_none(int executor_pid, bool enable_tun)
+{
+  int pid = fork();
+  if (pid)
+    return pid;
+
+  sandbox_common();
+
+  loop();
+  doexit(1);
+}
+
+static void remove_dir(const char* dir)
+{
+  DIR* dp;
+  struct dirent* ep;
+  int iter = 0;
+retry:
+  dp = opendir(dir);
+  if (dp == NULL) {
+    if (errno == EMFILE) {
+      exitf("opendir(%s) failed due to NOFILE, exiting");
+    }
+    exitf("opendir(%s) failed", dir);
+  }
+  while ((ep = readdir(dp))) {
+    if (strcmp(ep->d_name, ".") == 0 || strcmp(ep->d_name, "..") == 0)
+      continue;
+    char filename[FILENAME_MAX];
+    snprintf(filename, sizeof(filename), "%s/%s", dir, ep->d_name);
+    struct stat st;
+    if (lstat(filename, &st))
+      exitf("lstat(%s) failed", filename);
+    if (S_ISDIR(st.st_mode)) {
+      remove_dir(filename);
+      continue;
+    }
+    int i;
+    for (i = 0;; i++) {
+      debug("unlink(%s)\n", filename);
+      if (unlink(filename) == 0)
+        break;
+      if (errno == EROFS) {
+        debug("ignoring EROFS\n");
+        break;
+      }
+      if (errno != EBUSY || i > 100)
+        exitf("unlink(%s) failed", filename);
+      debug("umount(%s)\n", filename);
+      if (umount2(filename, MNT_DETACH))
+        exitf("umount(%s) failed", filename);
+    }
+  }
+  closedir(dp);
+  int i;
+  for (i = 0;; i++) {
+    debug("rmdir(%s)\n", dir);
+    if (rmdir(dir) == 0)
+      break;
+    if (i < 100) {
+      if (errno == EROFS) {
+        debug("ignoring EROFS\n");
+        break;
+      }
+      if (errno == EBUSY) {
+        debug("umount(%s)\n", dir);
+        if (umount2(dir, MNT_DETACH))
+          exitf("umount(%s) failed", dir);
+        continue;
+      }
+      if (errno == ENOTEMPTY) {
+        if (iter < 100) {
+          iter++;
+          goto retry;
+        }
+      }
+    }
+    exitf("rmdir(%s) failed", dir);
+  }
+}
+
+static uint64_t current_time_ms()
+{
+  struct timespec ts;
+
+  if (clock_gettime(CLOCK_MONOTONIC, &ts))
+    fail("clock_gettime failed");
+  return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
+}
+
+static void test();
+
+void loop()
+{
+  int iter;
+  for (iter = 0;; iter++) {
+    char cwdbuf[256];
+    sprintf(cwdbuf, "./%d", iter);
+    if (mkdir(cwdbuf, 0777))
+      fail("failed to mkdir");
+    int pid = fork();
+    if (pid < 0)
+      fail("clone failed");
+    if (pid == 0) {
+      prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
+      setpgrp();
+      if (chdir(cwdbuf))
+        fail("failed to chdir");
+      test();
+      doexit(0);
+    }
+    int status = 0;
+    uint64_t start = current_time_ms();
+    for (;;) {
+      int res = waitpid(-1, &status, __WALL | WNOHANG);
+      if (res == pid)
+        break;
+      usleep(1000);
+      if (current_time_ms() - start > 5 * 1000) {
+        kill(-pid, SIGKILL);
+        kill(pid, SIGKILL);
+        while (waitpid(-1, &status, __WALL) != pid) {
+        }
+        break;
+      }
+    }
+    remove_dir(cwdbuf);
+  }
+}
+
+long r[15];
+void test()
+{
+  memset(r, -1, sizeof(r));
+  r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x5000ul, 0x3ul,
+                         0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
+  NONFAILING(memcpy((void*)0x20000000,
+//                    "\x2f\x64\x65\x76\x2f\x73\x67\x23\x00", 9));
+                    dev_sg, strlen(dev_sg)));
+  r[2] = execute_syscall(__NR_syz_open_dev, 0x20000000ul, 0x0ul, 0x2ul,
+                         0, 0, 0, 0, 0, 0);
+  NONFAILING(*(uint64_t*)0x20001fdc = (uint64_t)0x0);
+  NONFAILING(*(uint64_t*)0x20001fe4 = (uint64_t)0x0);
+  NONFAILING(*(uint16_t*)0x20001fec = (uint16_t)0x3);
+  NONFAILING(*(uint16_t*)0x20001fee = (uint16_t)0x4);
+  NONFAILING(*(uint32_t*)0x20001ff0 = (uint32_t)0x9);
+  NONFAILING(*(uint64_t*)0x20001ff4 = (uint64_t)0x0);
+  NONFAILING(*(uint64_t*)0x20001ffc = (uint64_t)0x2710);
+  NONFAILING(*(uint16_t*)0x20002004 = (uint16_t)0x7);
+  NONFAILING(*(uint16_t*)0x20002006 = (uint16_t)0x7);
+  NONFAILING(*(uint32_t*)0x20002008 = (uint32_t)0x8);
+  r[13] = execute_syscall(__NR_write, r[2], 0x20001fdcul, 0x30ul, 0, 0,
+                          0, 0, 0, 0);
+  r[14] = execute_syscall(__NR_read, r[2], 0x20002f36ul, 0x0ul, 0, 0, 0,
+                          0, 0, 0);
+}
+int main(int argc, char **argv)
+{
+  if (argc == 2)
+    dev_sg = strdup(argv[1]);
+  else
+    dev_sg = "/dev/sg0";
+
+  setup_main_process();
+  int pid = do_sandbox_none(0, false);
+  int status = 0;
+  while (waitpid(pid, &status, __WALL) != pid) {
+  }
+  return 0;
+}
