net: WARNING in dccp_set_state

[Dmitry Vyukov]

Hello,

The following program triggers WARNING in dccp_set_state.
Also note the subsequent print:
dccp_close: ABORT with 4294967274 bytes unread
also looks quite suspicious (underflow?).

------------[ cut here ]------------
WARNING: CPU: 0 PID: 6889 at net/dccp/proto.c:83 dccp_set_state+0x247/0x420()
Modules linked in:
CPU: 0 PID: 6889 Comm: syz-executor Not tainted 4.4.0+ #273
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 00000000ffffffff ffff880033ff7818 ffffffff8299464d 0000000000000000
 ffff8800341e17c0 ffffffff86f496a0 ffff880033ff7858 ffffffff81352089
 ffffffff85d1b9b7 ffffffff86f496a0 0000000000000053 0000000000000007
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff8299464d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
 [<ffffffff81352089>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
 [<ffffffff813522b9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
 [<ffffffff85d1b9b7>] dccp_set_state+0x247/0x420 net/dccp/proto.c:83
 [<ffffffff85d1f30b>] dccp_close+0x52b/0xb50 net/dccp/proto.c:1016
 [<ffffffff856147ef>] inet_release+0xef/0x1c0 net/ipv4/af_inet.c:416
 [<ffffffff8573a5f0>] inet6_release+0x50/0x70 net/ipv6/af_inet6.c:409
 [<ffffffff851c1bff>] sock_release+0x8f/0x1d0 net/socket.c:572
 [<ffffffff851c1d56>] sock_close+0x16/0x20 net/socket.c:1023
 [<ffffffff817b36f6>] __fput+0x236/0x780 fs/file_table.c:208
 [<ffffffff817b3cc5>] ____fput+0x15/0x20 fs/file_table.c:244
 [<ffffffff813af2b0>] task_work_run+0x170/0x210 kernel/task_work.c:115
 [<     inline     >] exit_task_work include/linux/task_work.h:21
 [<ffffffff8135b275>] do_exit+0x8b5/0x2c60 kernel/exit.c:750
 [<ffffffff8135d798>] do_group_exit+0x108/0x330 kernel/exit.c:880
 [<ffffffff813806e4>] get_signal+0x5e4/0x14f0 kernel/signal.c:2307
 [<ffffffff811a2db3>] do_signal+0x83/0x1c90 arch/x86/kernel/signal.c:712
 [<ffffffff81006685>] exit_to_usermode_loop+0x1a5/0x210
arch/x86/entry/common.c:247
 [<     inline     >] prepare_exit_to_usermode arch/x86/entry/common.c:282
 [<ffffffff810084ea>] syscall_return_slowpath+0x2ba/0x340
arch/x86/entry/common.c:344
 [<ffffffff86330662>] int_ret_from_sys_call+0x25/0x9f
arch/x86/entry/entry_64.S:281
---[ end trace 99891e826168782f ]---
dccp_close: ABORT with 4294967274 bytes unread
------------[ cut here ]------------

// autogenerated by syzkaller (http://github.com/google/syzkaller)
#include <pthread.h>
#include <stdint.h>
#include <string.h>
#include <sys/syscall.h>
#include <unistd.h>

long r[15];

void* thr(void* arg)
{
  switch ((long)arg) {
  case 0:
    r[0] = syscall(SYS_mmap, 0x20000000ul, 0x600000ul, 0x3ul, 0x32ul,
                   0xfffffffffffffffful, 0x0ul);
    break;
  case 1:
    r[1] = syscall(SYS_socket, 0xaul, 0x80806ul, 0x0ul, 0, 0, 0);
    break;
  case 2:
    memcpy((void*)0x20000fca,
           "\x0a\x00\x33\xe2\x8c\xb2\x7f\x3e\x00\x00\x00\x00\x00\x00"
           "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x30\x8c\x2d\x7b"
           "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
           "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
           "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
           "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
           "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
           "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
           "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
           "\x00\x00",
           128);
    r[3] = syscall(SYS_connect, r[1], 0x20000fcaul, 0x80ul, 0, 0, 0);
    break;
  case 3:
    *(uint16_t*)0x20004dae = (uint16_t)0x0;
    *(uint8_t*)0x20004db0 = (uint8_t)0x0;
    *(uint32_t*)0x20004db2 = (uint32_t)0x9;
    r[7] = syscall(SYS_connect, r[1], 0x20004da6ul, 0x7ul, 0, 0, 0);
    break;
  case 4:
    *(uint16_t*)0x2053e22b = (uint16_t)0x1;
    *(uint64_t*)0x2053e233 = (uint64_t)0x2053eff8;
    *(uint16_t*)0x2053eff8 = (uint16_t)0x6;
    *(uint8_t*)0x2053effa = (uint8_t)0x0;
    *(uint8_t*)0x2053effb = (uint8_t)0x101;
    *(uint32_t*)0x2053effc = (uint32_t)0x6;
    r[14] = syscall(SYS_setsockopt, r[1], 0x1ul, 0x1aul, 0x2053e22bul,
                    0x10ul, 0);
    break;
  }
  return 0;
}

int main()
{
  long i;
  pthread_t th[5];

  memset(r, -1, sizeof(r));
  for (i = 0; i < 5; i++) {
    pthread_create(&th[i], 0, thr, (void*)i);
    usleep(10000);
  }
  for (i = 0; i < 5; i++) {
    pthread_create(&th[i], 0, thr, (void*)i);
    if (i % 2 == 0)
      usleep(10000);
  }
  usleep(100000);
  return 0;
}

On commit a200dcb34693084e56496960d855afdeaaf9578f