Message-ID: <CACT4Y+bFh_S3=U+JF7GCzZjZ9R8b_Xqzi-1AyruKxqNqGrFVrQ@mail.gmail.com>
Date:   Fri, 1 Feb 2019 17:48:27 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        jolsa@...hat.com, Namhyung Kim <namhyung@...nel.org>,
        luca abeni <luca.abeni@...tannapisa.it>
Cc:     syzkaller <syzkaller@...glegroups.com>
Subject: perf_event_open+clone = unkillable process

Hello,

The following program creates an unkillable process that eats CPU.
/proc/pid/stack is empty, I am not sure what other info I can provide.

Tested is on upstream commit 4aa9fc2a435abe95a1e8d7f8c7b3d6356514b37a.
Config is attached.

FTR, generated from the following syzkaller program:

perf_event_open(&(0x7f0000000580)={0x2, 0x70, 0x5c61, 0x2, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, @perf_config_ext}, 0x0,
0xffffffffffffffff, 0xffffffffffffffff, 0x0)
clone(0x20002100, 0x0, 0xfffffffffffffffe, 0x0, 0xffffffffffffffff)
r0 = gettid()
timer_create(0x0, &(0x7f0000000000)={0x0, 0x7, 0x4, @tid=r0}, &(0x7f0000000080))
timer_settime(0x0, 0x3, &(0x7f0000000140)={{0x0, 0x1}, {0x0, 0x1c9c380}}, 0x0)


// autogenerated by syzkaller (https://github.com/google/syzkaller)
#define _GNU_SOURCE
#include <endian.h>
#include <errno.h>
#include <pthread.h>
#include <setjmp.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

#include <linux/futex.h>

static __thread int skip_segv;
static __thread jmp_buf segv_env;

static void segv_handler(int sig, siginfo_t* info, void* ctx)
{
  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)) {
    _longjmp(segv_env, 1);
  }
  exit(sig);
}

static void install_segv_handler(void)
{
  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);
  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);                       \
  }

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;
  for (i = 0; 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);
}

#define BITMASK(bf_off, bf_len) (((1ull << (bf_len)) - 1) << (bf_off))
#define STORE_BY_BITMASK(type, htobe, addr, val, bf_off, bf_len)               \
  *(type*)(addr) =                                                             \
      htobe((htobe(*(type*)(addr)) & ~BITMASK((bf_off), (bf_len))) |           \
            (((type)(val) << (bf_off)) & BITMASK((bf_off), (bf_len))))

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);
}

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_RELAXED))
      return 1;
    now = current_time_ms();
    if (now - start > timeout)
      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 loop(void)
{
  int i, call, thread;
  for (call = 0; call < 5; 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);
      event_timedwait(&th->done, 45);
      break;
    }
  }
  for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++)
    sleep_ms(1);
}

uint64_t r[1] = {0x0};

void execute_call(int call)
{
  long res;
  switch (call) {
  case 0:
    NONFAILING(*(uint32_t*)0x20000580 = 2);
    NONFAILING(*(uint32_t*)0x20000584 = 0x70);
    NONFAILING(*(uint8_t*)0x20000588 = 0x61);
    NONFAILING(*(uint8_t*)0x20000589 = 2);
    NONFAILING(*(uint8_t*)0x2000058a = 0);
    NONFAILING(*(uint8_t*)0x2000058b = 0);
    NONFAILING(*(uint32_t*)0x2000058c = 0);
    NONFAILING(*(uint64_t*)0x20000590 = 0);
    NONFAILING(*(uint64_t*)0x20000598 = 0);
    NONFAILING(*(uint64_t*)0x200005a0 = 0);
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 0, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 1, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 2, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 3, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 4, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 5, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 6, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 7, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 8, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 9, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 10, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 11, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 12, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 13, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 14, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 15, 2));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 17, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 18, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 19, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 20, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 21, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 22, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 23, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 24, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 25, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 26, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 27, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 28, 1));
    NONFAILING(STORE_BY_BITMASK(uint64_t, , 0x200005a8, 0, 29, 35));
    NONFAILING(*(uint32_t*)0x200005b0 = 0);
    NONFAILING(*(uint32_t*)0x200005b4 = 0);
    NONFAILING(*(uint64_t*)0x200005b8 = 0);
    NONFAILING(*(uint64_t*)0x200005c0 = 0);
    NONFAILING(*(uint64_t*)0x200005c8 = 0);
    NONFAILING(*(uint64_t*)0x200005d0 = 0);
    NONFAILING(*(uint32_t*)0x200005d8 = 0);
    NONFAILING(*(uint32_t*)0x200005dc = 0);
    NONFAILING(*(uint64_t*)0x200005e0 = 0);
    NONFAILING(*(uint32_t*)0x200005e8 = 0);
    NONFAILING(*(uint16_t*)0x200005ec = 0);
    NONFAILING(*(uint16_t*)0x200005ee = 0);
    syscall(__NR_perf_event_open, 0x20000580, 0, -1, -1, 0);
    break;
  case 1:
    syscall(__NR_clone, 0x20002100, 0, 0x9999999999999999, 0, -1);
    break;
  case 2:
    res = syscall(__NR_gettid);
    if (res != -1)
      r[0] = res;
    break;
  case 3:
    NONFAILING(*(uint64_t*)0x20000000 = 0);
    NONFAILING(*(uint32_t*)0x20000008 = 7);
    NONFAILING(*(uint32_t*)0x2000000c = 4);
    NONFAILING(*(uint32_t*)0x20000010 = r[0]);
    syscall(__NR_timer_create, 0, 0x20000000, 0x20000080);
    break;
  case 4:
    NONFAILING(*(uint64_t*)0x20000140 = 0);
    NONFAILING(*(uint64_t*)0x20000148 = 1);
    NONFAILING(*(uint64_t*)0x20000150 = 0);
    NONFAILING(*(uint64_t*)0x20000158 = 0x1c9c380);
    syscall(__NR_timer_settime, 0, 3, 0x20000140, 0);
    break;
  }
}
int main(void)
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  install_segv_handler();
  loop();
  return 0;
}

Download attachment ".config" of type "application/octet-stream" (157716 bytes)

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