net/atm: warning in alloc_tx/__might_sleep

* net/atm: warning in alloc_tx/__might_sleep
@ 2017-01-09 17:20 Andrey Konovalov
  2017-01-10 17:35 ` Cong Wang
  2017-01-11 14:37 ` Chas Williams
  0 siblings, 2 replies; 14+ messages in thread
From: Andrey Konovalov @ 2017-01-09 17:20 UTC (permalink / raw)
  To: David S. Miller, Alexey Kuznetsov, James Morris,
	Hideaki YOSHIFUJI, Patrick McHardy, netdev, LKML, Al Viro
  Cc: Dmitry Vyukov, Kostya Serebryany, Eric Dumazet, syzkaller

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Hi!

I've got the following error report while running the syzkaller fuzzer.

On commit a121103c922847ba5010819a3f250f1f7fc84ab8 (4.10-rc3).

A reproducer is attached.

------------[ cut here ]------------
WARNING: CPU: 0 PID: 4114 at kernel/sched/core.c:7737 __might_sleep+0x149/0x1a0
do not call blocking ops when !TASK_RUNNING; state=1 set at
[<ffffffff813fcb22>] prepare_to_wait+0x182/0x530
Modules linked in:
CPU: 0 PID: 4114 Comm: a.out Not tainted 4.10.0-rc3+ #59
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:15
 dump_stack+0x292/0x398 lib/dump_stack.c:51
 __warn+0x19f/0x1e0 kernel/panic.c:547
 warn_slowpath_fmt+0xc5/0x110 kernel/panic.c:562
 __might_sleep+0x149/0x1a0 kernel/sched/core.c:7732
 slab_pre_alloc_hook mm/slab.h:408
 slab_alloc_node mm/slub.c:2634
 kmem_cache_alloc_node+0x14a/0x280 mm/slub.c:2744
 __alloc_skb+0x10f/0x800 net/core/skbuff.c:219
 alloc_skb ./include/linux/skbuff.h:926
 alloc_tx net/atm/common.c:75
 vcc_sendmsg+0x5e8/0x1010 net/atm/common.c:609
 sock_sendmsg_nosec net/socket.c:635
 sock_sendmsg+0xca/0x110 net/socket.c:645
 ___sys_sendmsg+0x9d2/0xae0 net/socket.c:1985
 __sys_sendmsg+0x138/0x320 net/socket.c:2019
 SYSC_sendmsg net/socket.c:2030
 SyS_sendmsg+0x2d/0x50 net/socket.c:2026
 entry_SYSCALL_64_fastpath+0x1f/0xc2 arch/x86/entry/entry_64.S:203
RIP: 0033:0x7fcbacfddb79
RSP: 002b:00007ffed8b5a7b8 EFLAGS: 00000206 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffed8b5a950 RCX: 00007fcbacfddb79
RDX: 000000000000c000 RSI: 0000000020002000 RDI: 0000000000000003
RBP: 0000000000400af0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007ffed8b5a950 R14: 0000000000000000 R15: 0000000000000000
---[ end trace 9edf2da84d8112da ]---
atm:sigd_send: bad message type 0

[-- Attachment #2: sched-sleep-warn-poc.c --]
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// autogenerated by syzkaller (http://github.com/google/syzkaller)

#ifndef __NR_mmap
#define __NR_mmap 9
#endif
#ifndef __NR_socket
#define __NR_socket 41
#endif
#ifndef __NR_ioctl
#define __NR_ioctl 16
#endif
#ifndef __NR_sendmsg
#define __NR_sendmsg 46
#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 <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 doexit(int status)
{
  syscall(__NR_exit_group, status);
  volatile unsigned i;
  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 ? 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)
{
  if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED))
    _longjmp(segv_env, 1);
  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);               \
  }

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();
  doexit(1);
}

long r[11];
void loop()
{
  memset(r, -1, sizeof(r));
  r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x4000ul, 0x3ul,
                         0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
  r[1] = execute_syscall(__NR_socket, 0x8ul, 0x0ul, 0x0ul, 0, 0, 0, 0,
                         0, 0);
  r[2] = execute_syscall(__NR_ioctl, r[1], 0x61f0ul, 0x20003000ul, 0, 0,
                         0, 0, 0, 0);
  NONFAILING(*(uint64_t*)0x20002000 = (uint64_t)0x0);
  NONFAILING(*(uint32_t*)0x20002008 = (uint32_t)0x0);
  NONFAILING(*(uint64_t*)0x20002010 = (uint64_t)0x20002000);
  NONFAILING(*(uint64_t*)0x20002018 = (uint64_t)0x2);
  NONFAILING(*(uint64_t*)0x20002020 = (uint64_t)0x0);
  NONFAILING(*(uint64_t*)0x20002028 = (uint64_t)0x0);
  NONFAILING(*(uint32_t*)0x20002030 = (uint32_t)0x0);
  r[10] = execute_syscall(__NR_sendmsg, r[1], 0x20002000ul, 0xc000ul, 0,
                          0, 0, 0, 0, 0);
}
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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