On Sat, Dec 3, 2016 at 2:49 PM, Eric Dumazet <eric.duma...@gmail.com> wrote:
> On Sat, 2016-12-03 at 14:05 +0100, Andrey Konovalov wrote:
>> On Sat, Dec 3, 2016 at 1:58 PM, Andrey Konovalov <andreyk...@google.com> 
>> wrote:
>> > +syzkal...@googlegroups.com
>> >
>> > On Sat, Dec 3, 2016 at 1:56 PM, Andrey Konovalov <andreyk...@google.com> 
>> > wrote:
>> >> Hi!
>> >>
>> >> I'm seeing lots of the following error reports while running the
>> >> syzkaller fuzzer.
>> >>
>> >> Reports appeared when I updated to 3c49de52 (Dec 2) from 2caceb32 (Dec 1).
>> >>
>> >> ==================================================================
>> >> BUG: KASAN: use-after-free in worker_thread+0x17d8/0x18a0
>> >> Read of size 8 at addr ffff880067f3ecd8 by task kworker/3:1/774
>> >>
>> >> page:ffffea00019fce00 count:1 mapcount:0 mapping:          (null)
>> >> index:0xffff880067f39c10 compound_mapcount: 0
>> >> flags: 0x500000000004080(slab|head)
>> >> page dumped because: kasan: bad access detected
>> >>
>> >> CPU: 3 PID: 774 Comm: kworker/3:1 Not tainted 4.9.0-rc7+ #66
>> >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 
>> >> 01/01/2011
>> >>  ffff88006c267838 ffffffff81f882da ffffffff6c25e338 1ffff1000d84ce9a
>> >>  ffffed000d84ce92 ffff88006c25e340 0000000041b58ab3 ffffffff8541e198
>> >>  ffffffff81f88048 0000000100000000 0000000041b58ab3 ffffffff853d3ee8
>> >> Call Trace:
>> >>  [<     inline     >] __dump_stack lib/dump_stack.c:15
>> >>  [<ffffffff81f882da>] dump_stack+0x292/0x398 lib/dump_stack.c:51
>> >>  [<     inline     >] describe_address mm/kasan/report.c:262
>> >>  [<ffffffff817e50d1>] kasan_report_error+0x121/0x560 mm/kasan/report.c:368
>> >>  [<     inline     >] kasan_report mm/kasan/report.c:390
>> >>  [<ffffffff817e560e>] __asan_report_load8_noabort+0x3e/0x40
>> >> mm/kasan/report.c:411
>> >>  [<ffffffff81329b88>] worker_thread+0x17d8/0x18a0 kernel/workqueue.c:2228
>> >>  [<ffffffff8133ebf3>] kthread+0x323/0x3e0 kernel/kthread.c:209
>> >>  [<ffffffff84a2a22a>] ret_from_fork+0x2a/0x40 
>> >> arch/x86/entry/entry_64.S:433
>> >>
>> >> The buggy address belongs to the object at ffff880067f3e6d0
>> >>  which belongs to the cache kmalloc-2048 of size 2048
>> >> The buggy address ffff880067f3ecd8 is located 1544 bytes inside
>> >>  of 2048-byte region [ffff880067f3e6d0, ffff880067f3eed0)
>> >>
>> >> Freed by task 0:
>> >>  [<ffffffff81203526>] save_stack_trace+0x16/0x20 
>> >> arch/x86/kernel/stacktrace.c:57
>> >>  [<ffffffff817e4173>] save_stack+0x43/0xd0 mm/kasan/kasan.c:495
>> >>  [<     inline     >] set_track mm/kasan/kasan.c:507
>> >>  [<ffffffff817e4a53>] kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:571
>> >>  [<     inline     >] slab_free_hook mm/slub.c:1352
>> >>  [<     inline     >] slab_free_freelist_hook mm/slub.c:1374
>> >>  [<     inline     >] slab_free mm/slub.c:2951
>> >>  [<ffffffff817e0eb7>] kfree+0xe7/0x2b0 mm/slub.c:3871
>> >>  [<     inline     >] sk_prot_free net/core/sock.c:1372
>> >>  [<ffffffff831ea1c7>] __sk_destruct+0x5c7/0x6e0 net/core/sock.c:1445
>> >>  [<ffffffff831f3517>] sk_destruct+0x47/0x80 net/core/sock.c:1453
>> >>  [<ffffffff831f35a7>] __sk_free+0x57/0x230 net/core/sock.c:1461
>> >>  [<ffffffff831f37a3>] sk_free+0x23/0x30 net/core/sock.c:1472
>> >>  [<     inline     >] sock_put include/net/sock.h:1591
>> >>  [<ffffffff8348ca9c>] deferred_put_nlk_sk+0x2c/0x40 
>> >> net/netlink/af_netlink.c:671
>> >>  [<     inline     >] __rcu_reclaim kernel/rcu/rcu.h:118
>> >>  [<ffffffff8146d42f>] rcu_do_batch.isra.67+0x8ff/0xc50 
>> >> kernel/rcu/tree.c:2776
>> >>  [<     inline     >] invoke_rcu_callbacks kernel/rcu/tree.c:3040
>> >>  [<     inline     >] __rcu_process_callbacks kernel/rcu/tree.c:3007
>> >>  [<ffffffff8146e097>] rcu_process_callbacks+0x2b7/0xba0 
>> >> kernel/rcu/tree.c:3024
>> >>  [<ffffffff84a2d08b>] __do_softirq+0x2fb/0xb63 kernel/softirq.c:284
>> >>
>> >> Allocated by task 10748:
>> >>  [<ffffffff81203526>] save_stack_trace+0x16/0x20 
>> >> arch/x86/kernel/stacktrace.c:57
>> >>  [<ffffffff817e4173>] save_stack+0x43/0xd0 mm/kasan/kasan.c:495
>> >>  [<     inline     >] set_track mm/kasan/kasan.c:507
>> >>  [<ffffffff817e43fd>] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:598
>> >>  [<ffffffff817e0050>] __kmalloc+0xa0/0x2d0 mm/slub.c:3734
>> >>  [<     inline     >] kmalloc include/linux/slab.h:495
>> >>  [<ffffffff831e4c01>] sk_prot_alloc+0x101/0x2a0 net/core/sock.c:1333
>> >>  [<ffffffff831efd15>] sk_alloc+0x105/0x1000 net/core/sock.c:1389
>> >>  [<ffffffff8348ad46>] __netlink_create+0x66/0x1d0 
>> >> net/netlink/af_netlink.c:588
>> >>  [<ffffffff8348cdab>] netlink_create+0x2fb/0x500 
>> >> net/netlink/af_netlink.c:647
>> >>  [<ffffffff831dd1d6>] __sock_create+0x4f6/0x880 net/socket.c:1168
>> >>  [<     inline     >] sock_create net/socket.c:1208
>> >>  [<     inline     >] SYSC_socket net/socket.c:1238
>> >>  [<ffffffff831dd799>] SyS_socket+0xf9/0x230 net/socket.c:1218
>> >>  [<ffffffff84a29fc1>] entry_SYSCALL_64_fastpath+0x1f/0xc2
>> >>
>> >> Memory state around the buggy address:
>> >>  ffff880067f3eb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> >>  ffff880067f3ec00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> >>>ffff880067f3ec80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> >>                                                     ^
>> >>  ffff880067f3ed00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> >>  ffff880067f3ed80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> >> ==================================================================
>>
>> Here is another report that looks related:
>>
>> ==================================================================
>> BUG: KASAN: use-after-free in __list_add+0x236/0x2c0
>> Read of size 8 at addr ffff880068854780 by task ksoftirqd/2/20
>>
>> page:ffffea0001a21400 count:1 mapcount:0 mapping:          (null)
>> index:0x0 compound_mapcount: 0
>> flags: 0x500000000004080(slab|head)
>> page dumped because: kasan: bad access detected
>>
>> CPU: 2 PID: 20 Comm: ksoftirqd/2 Not tainted 4.9.0-rc7+ #66
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>  ffff88006daf6578 ffffffff81f882da ffffffff6daf62a0 1ffff1000db5ec42
>>  ffffed000db5ec3a dffffc0000000000 0000000041b58ab3 ffffffff8541e198
>>  ffffffff81f88048 ffff88006dac3610 ffff88006daf6300 0000000000000802
>> Call Trace:
>>  [<     inline     >] __dump_stack lib/dump_stack.c:15
>>  [<ffffffff81f882da>] dump_stack+0x292/0x398 lib/dump_stack.c:51
>>  [<     inline     >] describe_address mm/kasan/report.c:262
>>  [<ffffffff817e50d1>] kasan_report_error+0x121/0x560 mm/kasan/report.c:368
>>  [<     inline     >] kasan_report mm/kasan/report.c:390
>>  [<ffffffff817e560e>] __asan_report_load8_noabort+0x3e/0x40
>> mm/kasan/report.c:411
>>  [<ffffffff8200c166>] __list_add+0x236/0x2c0 lib/list_debug.c:30
>>  [<     inline     >] list_add_tail include/linux/list.h:77
>>  [<ffffffff8131e295>] insert_work+0x175/0x4b0 kernel/workqueue.c:1298
>>  [<ffffffff8131eb52>] __queue_work+0x582/0x11e0 kernel/workqueue.c:1459
>>  [<ffffffff81320c21>] queue_work_on+0x231/0x240 kernel/workqueue.c:1484
>>  [<     inline     >] queue_work include/linux/workqueue.h:474
>>  [<     inline     >] schedule_work include/linux/workqueue.h:532
>>  [<ffffffff8348c8cc>] netlink_sock_destruct+0x23c/0x2d0
>> net/netlink/af_netlink.c:361
>>  [<ffffffff831e9ce1>] __sk_destruct+0xe1/0x6e0 net/core/sock.c:1423
>>  [<ffffffff831f3517>] sk_destruct+0x47/0x80 net/core/sock.c:1453
>>  [<ffffffff831f35a7>] __sk_free+0x57/0x230 net/core/sock.c:1461
>>  [<ffffffff831f37a3>] sk_free+0x23/0x30 net/core/sock.c:1472
>>  [<     inline     >] sock_put include/net/sock.h:1591
>>  [<ffffffff8348ca9c>] deferred_put_nlk_sk+0x2c/0x40 
>> net/netlink/af_netlink.c:671
>>  [<     inline     >] __rcu_reclaim kernel/rcu/rcu.h:118
>>  [<ffffffff8146d42f>] rcu_do_batch.isra.67+0x8ff/0xc50 kernel/rcu/tree.c:2776
>>  [<     inline     >] invoke_rcu_callbacks kernel/rcu/tree.c:3040
>>  [<     inline     >] __rcu_process_callbacks kernel/rcu/tree.c:3007
>>  [<ffffffff8146e097>] rcu_process_callbacks+0x2b7/0xba0 
>> kernel/rcu/tree.c:3024
>>  [<ffffffff84a2d08b>] __do_softirq+0x2fb/0xb63 kernel/softirq.c:284
>>  [<ffffffff812d38c0>] run_ksoftirqd+0x20/0x60 kernel/softirq.c:676
>>  [<ffffffff81350132>] smpboot_thread_fn+0x562/0x860 kernel/smpboot.c:163
>>  [<ffffffff8133ebf3>] kthread+0x323/0x3e0 kernel/kthread.c:209
>>  [<ffffffff84a2a22a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433
>>
>> The buggy address belongs to the object at ffff880068854170
>>  which belongs to the cache kmalloc-2048 of size 2048
>> The buggy address ffff880068854780 is located 1552 bytes inside
>>  of 2048-byte region [ffff880068854170, ffff880068854970)
>>
>> Freed by task 20:
>>  [<ffffffff81203526>] save_stack_trace+0x16/0x20 
>> arch/x86/kernel/stacktrace.c:57
>>  [<ffffffff817e4173>] save_stack+0x43/0xd0 mm/kasan/kasan.c:495
>>  [<     inline     >] set_track mm/kasan/kasan.c:507
>>  [<ffffffff817e4a53>] kasan_slab_free+0x73/0xc0 mm/kasan/kasan.c:571
>>  [<     inline     >] slab_free_hook mm/slub.c:1352
>>  [<     inline     >] slab_free_freelist_hook mm/slub.c:1374
>>  [<     inline     >] slab_free mm/slub.c:2951
>>  [<ffffffff817e0eb7>] kfree+0xe7/0x2b0 mm/slub.c:3871
>>  [<     inline     >] sk_prot_free net/core/sock.c:1372
>>  [<ffffffff831ea1c7>] __sk_destruct+0x5c7/0x6e0 net/core/sock.c:1445
>>  [<ffffffff831f3517>] sk_destruct+0x47/0x80 net/core/sock.c:1453
>>  [<ffffffff831f35a7>] __sk_free+0x57/0x230 net/core/sock.c:1461
>>  [<ffffffff831f37a3>] sk_free+0x23/0x30 net/core/sock.c:1472
>>  [<     inline     >] sock_put include/net/sock.h:1591
>>  [<ffffffff8348ca9c>] deferred_put_nlk_sk+0x2c/0x40 
>> net/netlink/af_netlink.c:671
>>  [<     inline     >] __rcu_reclaim kernel/rcu/rcu.h:118
>>  [<ffffffff8146d42f>] rcu_do_batch.isra.67+0x8ff/0xc50 kernel/rcu/tree.c:2776
>>  [<     inline     >] invoke_rcu_callbacks kernel/rcu/tree.c:3040
>>  [<     inline     >] __rcu_process_callbacks kernel/rcu/tree.c:3007
>>  [<ffffffff8146e097>] rcu_process_callbacks+0x2b7/0xba0 
>> kernel/rcu/tree.c:3024
>>  [<ffffffff84a2d08b>] __do_softirq+0x2fb/0xb63 kernel/softirq.c:284
>>
>> Allocated by task 9480:
>>  [<ffffffff81203526>] save_stack_trace+0x16/0x20 
>> arch/x86/kernel/stacktrace.c:57
>>  [<ffffffff817e4173>] save_stack+0x43/0xd0 mm/kasan/kasan.c:495
>>  [<     inline     >] set_track mm/kasan/kasan.c:507
>>  [<ffffffff817e43fd>] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:598
>>  [<ffffffff817e0050>] __kmalloc+0xa0/0x2d0 mm/slub.c:3734
>>  [<     inline     >] kmalloc include/linux/slab.h:495
>>  [<ffffffff831e4c01>] sk_prot_alloc+0x101/0x2a0 net/core/sock.c:1333
>>  [<ffffffff831efd15>] sk_alloc+0x105/0x1000 net/core/sock.c:1389
>>  [<ffffffff8348ad46>] __netlink_create+0x66/0x1d0 
>> net/netlink/af_netlink.c:588
>>  [<ffffffff8348cdab>] netlink_create+0x2fb/0x500 net/netlink/af_netlink.c:647
>>  [<ffffffff831dd1d6>] __sock_create+0x4f6/0x880 net/socket.c:1168
>>  [<     inline     >] sock_create net/socket.c:1208
>>  [<     inline     >] SYSC_socket net/socket.c:1238
>>  [<ffffffff831dd799>] SyS_socket+0xf9/0x230 net/socket.c:1218
>>  [<ffffffff84a29fc1>] entry_SYSCALL_64_fastpath+0x1f/0xc2
>>
>> Memory state around the buggy address:
>>  ffff880068854680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff880068854700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> >ffff880068854780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>                    ^
>>  ffff880068854800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff880068854880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ==================================================================
>
>
> Hi Andrey. Please give us some rest during the week end ;)

Hi Eric,

Sorry, wanted to restart fuzzer on newer kernel and immediately
started getting enormous amount of crashes :)

>
> This looks like the bug I mentioned earlier for which I have a pending
> patch ? Can you try it ?

No, it seems that your patch doesn't help, this is apparently something else.

I've attached a reproducer.

Thanks!

>
> The RCU conversion done by Thomas was quite buggy.
>
> Thanks.
>
>
> diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
> index 
> 602e5ebe9db39ec6c72708628bc48efad9f0e680..c348c4a5ea4ecc05dcc9e2afbc069ab65a1a57fe
>  100644
> --- a/net/netlink/af_netlink.c
> +++ b/net/netlink/af_netlink.c
> @@ -475,8 +475,8 @@ static struct sock *netlink_lookup(struct net *net, int 
> protocol, u32 portid)
>
>         rcu_read_lock();
>         sk = __netlink_lookup(table, portid, net);
> -       if (sk)
> -               sock_hold(sk);
> +       if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
> +               sk = NULL;
>         rcu_read_unlock();
>
>         return sk;
> @@ -600,6 +600,7 @@ static int __netlink_create(struct net *net, struct 
> socket *sock,
>         }
>         init_waitqueue_head(&nlk->wait);
>
> +       sock_set_flag(sk, SOCK_RCU_FREE);
>         sk->sk_destruct = netlink_sock_destruct;
>         sk->sk_protocol = protocol;
>         return 0;
> @@ -664,13 +665,6 @@ static int netlink_create(struct net *net, struct socket 
> *sock, int protocol,
>         goto out;
>  }
>
> -static void deferred_put_nlk_sk(struct rcu_head *head)
> -{
> -       struct netlink_sock *nlk = container_of(head, struct netlink_sock, 
> rcu);
> -
> -       sock_put(&nlk->sk);
> -}
> -
>  static int netlink_release(struct socket *sock)
>  {
>         struct sock *sk = sock->sk;
> @@ -743,7 +737,7 @@ static int netlink_release(struct socket *sock)
>         local_bh_disable();
>         sock_prot_inuse_add(sock_net(sk), &netlink_proto, -1);
>         local_bh_enable();
> -       call_rcu(&nlk->rcu, deferred_put_nlk_sk);
> +       sock_put(sk);
>         return 0;
>  }
>
> diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
> index 
> 4fdb3831897775547f77c069a8018c0d2a253c8c..988d1a02487e37b7efd4872dd0ab6d230e5a2021
>  100644
> --- a/net/netlink/af_netlink.h
> +++ b/net/netlink/af_netlink.h
> @@ -33,7 +33,6 @@ struct netlink_sock {
>         struct module           *module;
>
>         struct rhash_head       node;
> -       struct rcu_head         rcu;
>         struct work_struct      work;
>  };
>
>
>
>
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// autogenerated by syzkaller (http://github.com/google/syzkaller)

#ifndef __NR_socket
#define __NR_socket 41
#endif
#ifndef __NR_write
#define __NR_write 1
#endif
#ifndef __NR_readv
#define __NR_readv 19
#endif
#ifndef __NR_mmap
#define __NR_mmap 9
#endif

#define _GNU_SOURCE

#include <sys/ioctl.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 <linux/capability.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <linux/sched.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;

__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);
  exit(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);
  exit(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)
{
  if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED))
    _longjmp(segv_env, 1);
  exit(sig);
}

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);               \
  }

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);
  }
}

static void setup_main_process(uint64_t pid, bool enable_tun)
{
  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 pid = fork();
  if (pid)
    return pid;
  sandbox_common();
  loop();
  exit(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();
      exit(0);
    }
    int status = 0;
    uint64_t start = current_time_ms();
    for (;;) {
      int res = waitpid(pid, &status, __WALL | WNOHANG);
      int errno0 = errno;
      if (res == pid)
        break;
      usleep(1000);
      if (current_time_ms() - start > 5 * 1000) {
        kill(-pid, SIGKILL);
        kill(pid, SIGKILL);
        waitpid(pid, &status, __WALL);
        break;
      }
    }
    remove_dir(cwdbuf);
  }
}

long r[7];
void* thr(void* arg)
{
  switch ((long)arg) {
  case 0:
    r[0] =
        execute_syscall(__NR_mmap, 0x20000000ul, 0xe43000ul, 0x3ul,
                        0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
    break;
  case 1:
    r[1] = execute_syscall(__NR_socket, 0x10ul, 0x3ul, 0x0ul, 0, 0, 0,
                           0, 0, 0);
    break;
  case 2:
    NONFAILING(memcpy((void*)0x20e42fe1,
                      "\x1f\x00\x00\x00\x1a\x00\x03\xf2\x00\x00\x13\xff"
                      "\x07\x00\x00\x77\x00\x00\xff\xff\xff\x7f\xd8\x00"
                      "\x00\x00\x00\x00\x00\x00\x34",
                      31));
    r[3] = execute_syscall(__NR_write, r[1], 0x20e42fe1ul, 0x1ful, 0, 0,
                           0, 0, 0, 0);
    break;
  case 3:
    NONFAILING(*(uint64_t*)0x20e41000 = (uint64_t)0x20e3ef11);
    NONFAILING(*(uint64_t*)0x20e41008 = (uint64_t)0x1);
    r[6] = execute_syscall(__NR_readv, r[1], 0x20e41000ul, 0x1ul, 0, 0,
                           0, 0, 0, 0);
    break;
  }
  return 0;
}

void test()
{
  long i;
  pthread_t th[8];

  memset(r, -1, sizeof(r));
  srand(getpid());
  for (i = 0; i < 4; i++) {
    pthread_create(&th[i], 0, thr, (void*)i);
    usleep(10000);
  }
  usleep(100000);
}

int main()
{
  setup_main_process(0, false);
  int pid = do_sandbox_none();
  int status = 0;
  while (waitpid(pid, &status, __WALL) != pid) {
  }
  return 0;
}

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