Message-ID: <CALAgD-6MJC+D0DzxLOpVvCbYzHE-r1YzNORtpOh-f+hgEkMjzg@mail.gmail.com>
Date: Wed, 28 Aug 2024 14:05:12 -0700
From: Xingyu Li <xli399@....edu>
To: mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com, 
	vincent.guittot@...aro.org, dietmar.eggemann@....com, rostedt@...dmis.org, 
	bsegall@...gle.com, mgorman@...e.de, vschneid@...hat.com, 
	linux-kernel@...r.kernel.org
Cc: Yu Hao <yhao016@....edu>
Subject: BUG: WARNING: ODEBUG bug in schedule_timeout

Hi,

We found a bug in Linux 6.10. It is possibly a use-before-initialization  bug.
The bug report and the reproducer are as follows:

Bug report:

ODEBUG: assert_init not available (active state 0) object:
ffffc9000a9cf540 object type: timer_list hint:
process_timeout+0x0/0x40
WARNING: CPU: 0 PID: 8051 at lib/debugobjects.c:517
debug_print_object+0x176/0x1e0 lib/debugobjects.c:514
Modules linked in:
CPU: 0 PID: 8051 Comm: syz-executor163 Not tainted 6.10.0 #13
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:debug_print_object+0x176/0x1e0 lib/debugobjects.c:514
Code: df e8 6e e9 95 fd 4c 8b 0b 48 c7 c7 a0 61 a9 8b 48 8b 74 24 08
48 89 ea 44 89 e1 4d 89 f8 ff 34 24 e8 de 2c f7 fc 48 83 c4 08 <0f> 0b
ff 05 42 1e c6 0a 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d
RSP: 0018:ffffc9000a9cf298 EFLAGS: 00010282
RAX: 23ee1da135379d00 RBX: ffffffff8b4ee740 RCX: ffff88801a0c9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff8ba96360 R08: ffffffff8155a25a R09: 1ffff1100c74519a
R10: dffffc0000000000 R11: ffffed100c74519b R12: 0000000000000000
R13: ffffffff8ba96248 R14: dffffc0000000000 R15: ffffc9000a9cf540
FS:  000055558a14e3c0(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f79c90aaa60 CR3: 000000001f8be000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 debug_object_assert_init+0x35f/0x420 lib/debugobjects.c:910
 debug_timer_assert_init kernel/time/timer.c:846 [inline]
 debug_assert_init kernel/time/timer.c:891 [inline]
 __try_to_del_timer_sync kernel/time/timer.c:1504 [inline]
 __timer_delete_sync+0x2ba/0x410 kernel/time/timer.c:1665
 timer_delete_sync kernel/time/timer.c:1720 [inline]
 del_timer_sync include/linux/timer.h:185 [inline]
 schedule_timeout+0x1c3/0x300 kernel/time/timer.c:2582
 io_schedule_timeout+0x96/0x120 kernel/sched/core.c:9034
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common_io+0x31c/0x620 kernel/sched/completion.c:133
 blk_wait_io block/blk.h:82 [inline]
 blk_execute_rq+0x369/0x4a0 block/blk-mq.c:1408
 sg_scsi_ioctl drivers/scsi/scsi_ioctl.c:593 [inline]
 scsi_ioctl+0x20fc/0x2c70 drivers/scsi/scsi_ioctl.c:901
 sg_ioctl_common drivers/scsi/sg.c:1109 [inline]
 sg_ioctl+0x16c3/0x2d50 drivers/scsi/sg.c:1163
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xfe/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x7e/0x150 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x67/0x6f
RIP: 0033:0x7f6a2ca8418d
Code: c3 e8 a7 1f 00 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe3f6398f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000002fba0 RCX: 00007f6a2ca8418d
RDX: 0000000020000080 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 0000000000000000 R08: 002367732f766564 R09: 0000000000000000
R10: 000000000000000f R11: 0000000000000246 R12: 00007ffe3f63990c
R13: 431bde82d7b634db R14: 00007f6a2cb014f0 R15: 0000000000000001
 </TASK>

C reproducer:
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

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 bool write_file(const char* file, const char* what, ...)
{
  char buf[1024];
  va_list args;
  va_start(args, what);
  vsnprintf(buf, sizeof(buf), what, args);
  va_end(args);
  buf[sizeof(buf) - 1] = 0;
  int len = strlen(buf);
  int fd = open(file, O_WRONLY | O_CLOEXEC);
  if (fd == -1)
    return false;
  if (write(fd, buf, len) != len) {
    int err = errno;
    close(fd);
    errno = err;
    return false;
  }
  close(fd);
  return true;
}

static long syz_open_dev(volatile long a0, volatile long a1, volatile long 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;
    strncpy(buf, (char*)a0, sizeof(buf) - 1);
    buf[sizeof(buf) - 1] = 0;
    while ((hash = strchr(buf, '#'))) {
      *hash = '0' + (char)(a1 % 10);
      a1 /= 10;
    }
    return open(buf, a2, 0);
  }
}

static void kill_and_wait(int pid, int* status)
{
  kill(-pid, SIGKILL);
  kill(pid, SIGKILL);
  for (int i = 0; i < 100; i++) {
    if (waitpid(-1, status, WNOHANG | __WALL) == pid)
      return;
    usleep(1000);
  }
  DIR* dir = opendir("/sys/fs/fuse/connections");
  if (dir) {
    for (;;) {
      struct dirent* ent = readdir(dir);
      if (!ent)
        break;
      if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
        continue;
      char abort[300];
      snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort",
               ent->d_name);
      int fd = open(abort, O_WRONLY);
      if (fd == -1) {
        continue;
      }
      if (write(fd, abort, 1) < 0) {
      }
      close(fd);
    }
    closedir(dir);
  } else {
  }
  while (waitpid(-1, status, __WALL) != pid) {
  }
}

static void setup_test()
{
  prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
  setpgrp();
  write_file("/proc/self/oom_score_adj", "1000");
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
  int iter = 0;
  for (;; iter++) {
    int pid = fork();
    if (pid < 0)
      exit(1);
    if (pid == 0) {
      setup_test();
      execute_one();
      exit(0);
    }
    int status = 0;
    uint64_t start = current_time_ms();
    for (;;) {
      sleep_ms(10);
      if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
        break;
      if (current_time_ms() - start < 5000)
        continue;
      kill_and_wait(pid, &status);
      break;
    }
  }
}

uint64_t r[1] = {0xffffffffffffffff};

void execute_one(void)
{
  intptr_t res = 0;
  if (write(1, "executing program\n", sizeof("executing program\n") - 1)) {
  }
  memcpy((void*)0x20000000,
         "\x2b\x95\x24\x80\xc7\xca\x55\x09\x7d\x17\x07\x93\x5b\xa6\x4b\x20\xf3"
         "\x02\x6c\x03\xd6\x58\x02\x6b\x81\xbf\x26\x43\x40\x51\x2b\x3c\xb4\xe0"
         "\x1a\xfd\xa2\xde\x75\x42\x99\xea\x7a\x11\x33\x43\xab\x7b\x9b\xda\x2f"
         "\xc0\xa2\xe2\xcd\xbf\xec\xbc\xa0\x23\x3a\x07\x72\xb1\x2e\xbd\xe5\xd9"
         "\x8a\x12\x03\xcb\x87\x16\x72\xdf\xf7\xe4\xc8\x6e\xc1\xdc\xce\xf0\xa7"
         "\x63\x12\xfb\xe8\xd4\x5d\xc2\xbd\x0f\x8f\xc2\xeb\xeb\x2a\x6b\xe6\xa3"
         "\x00\x91\x6c\x52\x81\xda\x2c\x1e\xf6\x4d\x66\x26\x70\x91\xb8\x24\x29"
         "\x97\x6c\x01\x9d\xa3\x64\x55\x57\xed\x1d\x43\x9c\x5a\x63\x7f\x6b\xf5"
         "\x8c\x53\xbc\x41\x45\x39\xdd\x87\xc6\x90\x98\xd6\x71\x40\x25\x86\xb6"
         "\x31\xf9\xac\x5c\x2f\xe9\xce\xdc\x28\x1a\x6f\x00\x5b\x5c\x4d\x1d\xd5"
         "\xed\x9b\xe4\x00\x00\x00\x00\x00\x00\x00",
         180);
  syscall(__NR_write, /*fd=*/-1, /*arg0=*/0x20000000ul, /*len=*/0xb4ul);
  memcpy((void*)0x20000080, "/dev/sg#\000", 9);
  res = -1;
  res = syz_open_dev(/*dev=*/0x20000080, /*id=*/0,
                     /*flags=O_CREAT|FASYNC|O_RDWR*/ 0x2042);
  if (res != -1)
    r[0] = res;
  *(uint32_t*)0x20000080 = 0;
  *(uint32_t*)0x20000084 = 2;
  *(uint8_t*)0x20000088 = 0x85;
  *(uint8_t*)0x20000089 = 8;
  *(uint8_t*)0x2000008a = 2;
  *(uint8_t*)0x2000008b = 0xd;
  syscall(__NR_ioctl, /*fd=*/r[0], /*arg0=*/1, /*arg1=*/0x20000080ul);
}
int main(void)
{
  syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
          /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul,
          /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
          /*offset=*/0ul);
  syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul,
          /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1,
          /*offset=*/0ul);
  const char* reason;
  (void)reason;
  loop();
  return 0;
}

-- 
Yours sincerely,
Xingyu

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