[Linux Kernel Bug] WARNING: ODEBUG bug in free_netdev

Dear developers and maintainers,

We encountered a kernel warning while using our modified syzkaller.
The bug has been reproduced on the latest kernel
commit(9b332cece987ee1790b2ed4c989e28162fa47860). The kernel crash log is
listed below.

cdc_ncm 2-1:1.0 usb5: unregister 'cdc_ncm' usb-dummy_hcd.1-1, CDC NCM (NO ZLP)
------------[ cut here ]------------
ODEBUG: free active (active state 0) object: ff1100004c40d280 object
type: work_struct hint: usbnet_deferred_kevent+0x0/0xea0
drivers/net/usb/usbnet.c:1439
WARNING: CPU: 0 PID: 975 at lib/debugobjects.c:612
debug_print_object+0x1a2/0x2b0 lib/debugobjects.c:612
Modules linked in:
CPU: 0 UID: 0 PID: 975 Comm: kworker/0:2 Not tainted
6.17.0-rc5-00018-g9dd1835ecda5 #8 PREEMPT(full)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Workqueue: usb_hub_wq hub_event
RIP: 0010:debug_print_object+0x1a2/0x2b0 lib/debugobjects.c:612
Code: fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 54 41 56 48 8b 14
dd e0 2b f6 8b 4c 89 e6 48 c7 c7 60 20 f6 8b e8 2f 10 9b fc 90 <0f> 0b
90 90 58 83 05 d6 da ac 0b 01 48 83 c4 18 5b 5d 41 5c 41 5d
RSP: 0018:ffa0000004d1f458 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000003 RCX: ffffffff81795e09
RDX: ff1100001cbd0000 RSI: ffffffff81795e16 RDI: 0000000000000001
RBP: 0000000000000001 R08: 0000000000000001 R09: ffe21c00056c4841
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8bf62700
R13: ffffffff8b8c1c20 R14: ffffffff8715d610 R15: ffa0000004d1f548
FS:  0000000000000000(0000) GS:ff11000097ada000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9983176020 CR3: 0000000046572000 CR4: 0000000000753ef0
PKRU: 55555554
Call Trace:
 <TASK>
 __debug_check_no_obj_freed lib/debugobjects.c:1099 [inline]
 debug_check_no_obj_freed+0x3ec/0x520 lib/debugobjects.c:1129
 slab_free_hook mm/slub.c:2353 [inline]
 slab_free mm/slub.c:4695 [inline]
 kfree+0x2b1/0x4e0 mm/slub.c:4894
 device_release+0xa6/0x240 drivers/base/core.c:2565
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1af/0x4c0 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3797
 free_netdev+0x61b/0x900 net/core/dev.c:12002
 usbnet_disconnect+0x25c/0x510 drivers/net/usb/usbnet.c:1673
 usb_unbind_interface+0x1e5/0x9c0 drivers/usb/core/driver.c:458
 device_remove drivers/base/dd.c:571 [inline]
 device_remove+0x122/0x170 drivers/base/dd.c:563
 __device_release_driver drivers/base/dd.c:1274 [inline]
 device_release_driver_internal+0x43e/0x610 drivers/base/dd.c:1297
 bus_remove_device+0x22f/0x420 drivers/base/bus.c:579
 device_del+0x396/0x9d0 drivers/base/core.c:3878
 usb_disable_device+0x359/0x7b0 drivers/usb/core/message.c:1418
 usb_disconnect+0x2df/0x9e0 drivers/usb/core/hub.c:2344
 hub_port_connect drivers/usb/core/hub.c:5406 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x1e6d/0x4e60 drivers/usb/core/hub.c:5952
 process_one_work+0x98f/0x1b60 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x67e/0xe90 kernel/workqueue.c:3400
 kthread+0x3cd/0x780 kernel/kthread.c:463
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Though syzbot reported similar bug
(https://syzkaller.appspot.com/bug?extid=8bfd7bcc98f7300afb84), we
have successfully reproduced the bug with the following C program:

#define _GNU_SOURCE

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <nftables/libnftables.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 <sys/mount.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>

#include <linux/usb/ch9.h>

#ifndef __NR_bpf
#define __NR_bpf 321
#endif

static unsigned long long procid;

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;
}

#define TCP_CONNECTIONS 8
#define UDP_CONNECTIONS 8
#define BASE_PORT 30000

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 int runcmdline(char* cmdline)
{
  int ret = system(cmdline);
  if (ret) {
  }
  return ret;
}

#define MAX_FDS 30

#define USB_MAX_IFACE_NUM 4
#define USB_MAX_EP_NUM 32
#define USB_MAX_FDS 6

struct usb_endpoint_index {
  struct usb_endpoint_descriptor desc;
  int handle;
};

struct usb_iface_index {
  struct usb_interface_descriptor* iface;
  uint8_t bInterfaceNumber;
  uint8_t bAlternateSetting;
  uint8_t bInterfaceClass;
  struct usb_endpoint_index eps[USB_MAX_EP_NUM];
  int eps_num;
};

struct usb_device_index {
  struct usb_device_descriptor* dev;
  struct usb_config_descriptor* config;
  uint8_t bDeviceClass;
  uint8_t bMaxPower;
  int config_length;
  struct usb_iface_index ifaces[USB_MAX_IFACE_NUM];
  int ifaces_num;
  int iface_cur;
};

struct usb_info {
  int fd;
  struct usb_device_index index;
};

static struct usb_info usb_devices[USB_MAX_FDS];

static struct usb_device_index* lookup_usb_index(int fd)
{
  for (int i = 0; i < USB_MAX_FDS; i++) {
    if (__atomic_load_n(&usb_devices[i].fd, __ATOMIC_ACQUIRE) == fd)
      return &usb_devices[i].index;
  }
  return NULL;
}

static int usb_devices_num;

static bool parse_usb_descriptor(const char* buffer, size_t length,
                                 struct usb_device_index* index)
{
  if (length < sizeof(*index->dev) + sizeof(*index->config))
    return false;
  memset(index, 0, sizeof(*index));
  index->dev = (struct usb_device_descriptor*)buffer;
  index->config = (struct usb_config_descriptor*)(buffer + sizeof(*index->dev));
  index->bDeviceClass = index->dev->bDeviceClass;
  index->bMaxPower = index->config->bMaxPower;
  index->config_length = length - sizeof(*index->dev);
  index->iface_cur = -1;
  size_t offset = 0;
  while (true) {
    if (offset + 1 >= length)
      break;
    uint8_t desc_length = buffer[offset];
    uint8_t desc_type = buffer[offset + 1];
    if (desc_length <= 2)
      break;
    if (offset + desc_length > length)
      break;
    if (desc_type == USB_DT_INTERFACE &&
        index->ifaces_num < USB_MAX_IFACE_NUM) {
      struct usb_interface_descriptor* iface =
          (struct usb_interface_descriptor*)(buffer + offset);
      index->ifaces[index->ifaces_num].iface = iface;
      index->ifaces[index->ifaces_num].bInterfaceNumber =
          iface->bInterfaceNumber;
      index->ifaces[index->ifaces_num].bAlternateSetting =
          iface->bAlternateSetting;
      index->ifaces[index->ifaces_num].bInterfaceClass = iface->bInterfaceClass;
      index->ifaces_num++;
    }
    if (desc_type == USB_DT_ENDPOINT && index->ifaces_num > 0) {
      struct usb_iface_index* iface = &index->ifaces[index->ifaces_num - 1];
      if (iface->eps_num < USB_MAX_EP_NUM) {
        memcpy(&iface->eps[iface->eps_num].desc, buffer + offset,
               sizeof(iface->eps[iface->eps_num].desc));
        iface->eps_num++;
      }
    }
    offset += desc_length;
  }
  return true;
}

static struct usb_device_index* add_usb_index(int fd, const char* dev,
                                              size_t dev_len)
{
  int i = __atomic_fetch_add(&usb_devices_num, 1, __ATOMIC_RELAXED);
  if (i >= USB_MAX_FDS)
    return NULL;
  if (!parse_usb_descriptor(dev, dev_len, &usb_devices[i].index))
    return NULL;
  __atomic_store_n(&usb_devices[i].fd, fd, __ATOMIC_RELEASE);
  return &usb_devices[i].index;
}

struct vusb_connect_string_descriptor {
  uint32_t len;
  char* str;
} __attribute__((packed));

struct vusb_connect_descriptors {
  uint32_t qual_len;
  char* qual;
  uint32_t bos_len;
  char* bos;
  uint32_t strs_len;
  struct vusb_connect_string_descriptor strs[0];
} __attribute__((packed));

static const char default_string[] = {8, USB_DT_STRING, 's', 0, 'y', 0, 'z', 0};

static const char default_lang_id[] = {4, USB_DT_STRING, 0x09, 0x04};

static bool
lookup_connect_response_in(int fd, const struct vusb_connect_descriptors* descs,
                           const struct usb_ctrlrequest* ctrl,
                           struct usb_qualifier_descriptor* qual,
                           char** response_data, uint32_t* response_length)
{
  struct usb_device_index* index = lookup_usb_index(fd);
  uint8_t str_idx;
  if (!index)
    return false;
  switch (ctrl->bRequestType & USB_TYPE_MASK) {
  case USB_TYPE_STANDARD:
    switch (ctrl->bRequest) {
    case USB_REQ_GET_DESCRIPTOR:
      switch (ctrl->wValue >> 8) {
      case USB_DT_DEVICE:
        *response_data = (char*)index->dev;
        *response_length = sizeof(*index->dev);
        return true;
      case USB_DT_CONFIG:
        *response_data = (char*)index->config;
        *response_length = index->config_length;
        return true;
      case USB_DT_STRING:
        str_idx = (uint8_t)ctrl->wValue;
        if (descs && str_idx < descs->strs_len) {
          *response_data = descs->strs[str_idx].str;
          *response_length = descs->strs[str_idx].len;
          return true;
        }
        if (str_idx == 0) {
          *response_data = (char*)&default_lang_id[0];
          *response_length = default_lang_id[0];
          return true;
        }
        *response_data = (char*)&default_string[0];
        *response_length = default_string[0];
        return true;
      case USB_DT_BOS:
        *response_data = descs->bos;
        *response_length = descs->bos_len;
        return true;
      case USB_DT_DEVICE_QUALIFIER:
        if (!descs->qual) {
          qual->bLength = sizeof(*qual);
          qual->bDescriptorType = USB_DT_DEVICE_QUALIFIER;
          qual->bcdUSB = index->dev->bcdUSB;
          qual->bDeviceClass = index->dev->bDeviceClass;
          qual->bDeviceSubClass = index->dev->bDeviceSubClass;
          qual->bDeviceProtocol = index->dev->bDeviceProtocol;
          qual->bMaxPacketSize0 = index->dev->bMaxPacketSize0;
          qual->bNumConfigurations = index->dev->bNumConfigurations;
          qual->bRESERVED = 0;
          *response_data = (char*)qual;
          *response_length = sizeof(*qual);
          return true;
        }
        *response_data = descs->qual;
        *response_length = descs->qual_len;
        return true;
      default:
        break;
      }
      break;
    default:
      break;
    }
    break;
  default:
    break;
  }
  return false;
}

typedef bool (*lookup_connect_out_response_t)(
    int fd, const struct vusb_connect_descriptors* descs,
    const struct usb_ctrlrequest* ctrl, bool* done);

static bool lookup_connect_response_out_generic(
    int fd, const struct vusb_connect_descriptors* descs,
    const struct usb_ctrlrequest* ctrl, bool* done)
{
  switch (ctrl->bRequestType & USB_TYPE_MASK) {
  case USB_TYPE_STANDARD:
    switch (ctrl->bRequest) {
    case USB_REQ_SET_CONFIGURATION:
      *done = true;
      return true;
    default:
      break;
    }
    break;
  }
  return false;
}

struct vusb_descriptor {
  uint8_t req_type;
  uint8_t desc_type;
  uint32_t len;
  char data[0];
} __attribute__((packed));

struct vusb_descriptors {
  uint32_t len;
  struct vusb_descriptor* generic;
  struct vusb_descriptor* descs[0];
} __attribute__((packed));

struct vusb_response {
  uint8_t type;
  uint8_t req;
  uint32_t len;
  char data[0];
} __attribute__((packed));

struct vusb_responses {
  uint32_t len;
  struct vusb_response* generic;
  struct vusb_response* resps[0];
} __attribute__((packed));

static bool lookup_control_response(const struct vusb_descriptors* descs,
                                    const struct vusb_responses* resps,
                                    struct usb_ctrlrequest* ctrl,
                                    char** response_data,
                                    uint32_t* response_length)
{
  int descs_num = 0;
  int resps_num = 0;
  if (descs)
    descs_num = (descs->len - offsetof(struct vusb_descriptors, descs)) /
                sizeof(descs->descs[0]);
  if (resps)
    resps_num = (resps->len - offsetof(struct vusb_responses, resps)) /
                sizeof(resps->resps[0]);
  uint8_t req = ctrl->bRequest;
  uint8_t req_type = ctrl->bRequestType & USB_TYPE_MASK;
  uint8_t desc_type = ctrl->wValue >> 8;
  if (req == USB_REQ_GET_DESCRIPTOR) {
    int i;
    for (i = 0; i < descs_num; i++) {
      struct vusb_descriptor* desc = descs->descs[i];
      if (!desc)
        continue;
      if (desc->req_type == req_type && desc->desc_type == desc_type) {
        *response_length = desc->len;
        if (*response_length != 0)
          *response_data = &desc->data[0];
        else
          *response_data = NULL;
        return true;
      }
    }
    if (descs && descs->generic) {
      *response_data = &descs->generic->data[0];
      *response_length = descs->generic->len;
      return true;
    }
  } else {
    int i;
    for (i = 0; i < resps_num; i++) {
      struct vusb_response* resp = resps->resps[i];
      if (!resp)
        continue;
      if (resp->type == req_type && resp->req == req) {
        *response_length = resp->len;
        if (*response_length != 0)
          *response_data = &resp->data[0];
        else
          *response_data = NULL;
        return true;
      }
    }
    if (resps && resps->generic) {
      *response_data = &resps->generic->data[0];
      *response_length = resps->generic->len;
      return true;
    }
  }
  return false;
}

#define UDC_NAME_LENGTH_MAX 128

struct usb_raw_init {
  __u8 driver_name[UDC_NAME_LENGTH_MAX];
  __u8 device_name[UDC_NAME_LENGTH_MAX];
  __u8 speed;
};

enum usb_raw_event_type {
  USB_RAW_EVENT_INVALID = 0,
  USB_RAW_EVENT_CONNECT = 1,
  USB_RAW_EVENT_CONTROL = 2,
};

struct usb_raw_event {
  __u32 type;
  __u32 length;
  __u8 data[0];
};

struct usb_raw_ep_io {
  __u16 ep;
  __u16 flags;
  __u32 length;
  __u8 data[0];
};

#define USB_RAW_EPS_NUM_MAX 30
#define USB_RAW_EP_NAME_MAX 16
#define USB_RAW_EP_ADDR_ANY 0xff

struct usb_raw_ep_caps {
  __u32 type_control : 1;
  __u32 type_iso : 1;
  __u32 type_bulk : 1;
  __u32 type_int : 1;
  __u32 dir_in : 1;
  __u32 dir_out : 1;
};

struct usb_raw_ep_limits {
  __u16 maxpacket_limit;
  __u16 max_streams;
  __u32 reserved;
};

struct usb_raw_ep_info {
  __u8 name[USB_RAW_EP_NAME_MAX];
  __u32 addr;
  struct usb_raw_ep_caps caps;
  struct usb_raw_ep_limits limits;
};

struct usb_raw_eps_info {
  struct usb_raw_ep_info eps[USB_RAW_EPS_NUM_MAX];
};

#define USB_RAW_IOCTL_INIT _IOW('U', 0, struct usb_raw_init)
#define USB_RAW_IOCTL_RUN _IO('U', 1)
#define USB_RAW_IOCTL_EVENT_FETCH _IOR('U', 2, struct usb_raw_event)
#define USB_RAW_IOCTL_EP0_WRITE _IOW('U', 3, struct usb_raw_ep_io)
#define USB_RAW_IOCTL_EP0_READ _IOWR('U', 4, struct usb_raw_ep_io)
#define USB_RAW_IOCTL_EP_ENABLE _IOW('U', 5, struct usb_endpoint_descriptor)
#define USB_RAW_IOCTL_EP_DISABLE _IOW('U', 6, __u32)
#define USB_RAW_IOCTL_EP_WRITE _IOW('U', 7, struct usb_raw_ep_io)
#define USB_RAW_IOCTL_EP_READ _IOWR('U', 8, struct usb_raw_ep_io)
#define USB_RAW_IOCTL_CONFIGURE _IO('U', 9)
#define USB_RAW_IOCTL_VBUS_DRAW _IOW('U', 10, __u32)
#define USB_RAW_IOCTL_EPS_INFO _IOR('U', 11, struct usb_raw_eps_info)
#define USB_RAW_IOCTL_EP0_STALL _IO('U', 12)
#define USB_RAW_IOCTL_EP_SET_HALT _IOW('U', 13, __u32)
#define USB_RAW_IOCTL_EP_CLEAR_HALT _IOW('U', 14, __u32)
#define USB_RAW_IOCTL_EP_SET_WEDGE _IOW('U', 15, __u32)

static int usb_raw_open()
{
  return open("/dev/raw-gadget", O_RDWR);
}

static int usb_raw_init(int fd, uint32_t speed, const char* driver,
                        const char* device)
{
  struct usb_raw_init arg;
  strncpy((char*)&arg.driver_name[0], driver, sizeof(arg.driver_name));
  strncpy((char*)&arg.device_name[0], device, sizeof(arg.device_name));
  arg.speed = speed;
  return ioctl(fd, USB_RAW_IOCTL_INIT, &arg);
}

static int usb_raw_run(int fd)
{
  return ioctl(fd, USB_RAW_IOCTL_RUN, 0);
}

static int usb_raw_configure(int fd)
{
  return ioctl(fd, USB_RAW_IOCTL_CONFIGURE, 0);
}

static int usb_raw_vbus_draw(int fd, uint32_t power)
{
  return ioctl(fd, USB_RAW_IOCTL_VBUS_DRAW, power);
}

static int usb_raw_ep0_write(int fd, struct usb_raw_ep_io* io)
{
  return ioctl(fd, USB_RAW_IOCTL_EP0_WRITE, io);
}

static int usb_raw_ep0_read(int fd, struct usb_raw_ep_io* io)
{
  return ioctl(fd, USB_RAW_IOCTL_EP0_READ, io);
}

static int usb_raw_event_fetch(int fd, struct usb_raw_event* event)
{
  return ioctl(fd, USB_RAW_IOCTL_EVENT_FETCH, event);
}

static int usb_raw_ep_enable(int fd, struct usb_endpoint_descriptor* desc)
{
  return ioctl(fd, USB_RAW_IOCTL_EP_ENABLE, desc);
}

static int usb_raw_ep_disable(int fd, int ep)
{
  return ioctl(fd, USB_RAW_IOCTL_EP_DISABLE, ep);
}

static int usb_raw_ep0_stall(int fd)
{
  return ioctl(fd, USB_RAW_IOCTL_EP0_STALL, 0);
}

static int lookup_interface(int fd, uint8_t bInterfaceNumber,
                            uint8_t bAlternateSetting)
{
  struct usb_device_index* index = lookup_usb_index(fd);
  if (!index)
    return -1;
  for (int i = 0; i < index->ifaces_num; i++) {
    if (index->ifaces[i].bInterfaceNumber == bInterfaceNumber &&
        index->ifaces[i].bAlternateSetting == bAlternateSetting)
      return i;
  }
  return -1;
}

#define USB_MAX_PACKET_SIZE 4096

struct usb_raw_control_event {
  struct usb_raw_event inner;
  struct usb_ctrlrequest ctrl;
  char data[USB_MAX_PACKET_SIZE];
};

struct usb_raw_ep_io_data {
  struct usb_raw_ep_io inner;
  char data[USB_MAX_PACKET_SIZE];
};

static void set_interface(int fd, int n)
{
  struct usb_device_index* index = lookup_usb_index(fd);
  if (!index)
    return;
  if (index->iface_cur >= 0 && index->iface_cur < index->ifaces_num) {
    for (int ep = 0; ep < index->ifaces[index->iface_cur].eps_num; ep++) {
      int rv = usb_raw_ep_disable(
          fd, index->ifaces[index->iface_cur].eps[ep].handle);
      if (rv < 0) {
      } else {
      }
    }
  }
  if (n >= 0 && n < index->ifaces_num) {
    for (int ep = 0; ep < index->ifaces[n].eps_num; ep++) {
      int rv = usb_raw_ep_enable(fd, &index->ifaces[n].eps[ep].desc);
      if (rv < 0) {
      } else {
        index->ifaces[n].eps[ep].handle = rv;
      }
    }
    index->iface_cur = n;
  }
}

static int configure_device(int fd)
{
  struct usb_device_index* index = lookup_usb_index(fd);
  if (!index)
    return -1;
  int rv = usb_raw_vbus_draw(fd, index->bMaxPower);
  if (rv < 0) {
    return rv;
  }
  rv = usb_raw_configure(fd);
  if (rv < 0) {
    return rv;
  }
  set_interface(fd, 0);
  return 0;
}

static volatile long
syz_usb_connect_impl(uint64_t speed, uint64_t dev_len, const char* dev,
                     const struct vusb_connect_descriptors* descs,
                     lookup_connect_out_response_t lookup_connect_response_out)
{
  if (!dev) {
    return -1;
  }
  int fd = usb_raw_open();
  if (fd < 0) {
    return fd;
  }
  if (fd >= MAX_FDS) {
    close(fd);
    return -1;
  }
  struct usb_device_index* index = add_usb_index(fd, dev, dev_len);
  if (!index) {
    return -1;
  }
  char device[32];
  sprintf(&device[0], "dummy_udc.%llu", procid);
  int rv = usb_raw_init(fd, speed, "dummy_udc", &device[0]);
  if (rv < 0) {
    return rv;
  }
  rv = usb_raw_run(fd);
  if (rv < 0) {
    return rv;
  }
  bool done = false;
  while (!done) {
    struct usb_raw_control_event event;
    event.inner.type = 0;
    event.inner.length = sizeof(event.ctrl);
    rv = usb_raw_event_fetch(fd, (struct usb_raw_event*)&event);
    if (rv < 0) {
      return rv;
    }
    if (event.inner.type != USB_RAW_EVENT_CONTROL)
      continue;
    char* response_data = NULL;
    uint32_t response_length = 0;
    struct usb_qualifier_descriptor qual;
    if (event.ctrl.bRequestType & USB_DIR_IN) {
      if (!lookup_connect_response_in(fd, descs, &event.ctrl, &qual,
                                      &response_data, &response_length)) {
        usb_raw_ep0_stall(fd);
        continue;
      }
    } else {
      if (!lookup_connect_response_out(fd, descs, &event.ctrl, &done)) {
        usb_raw_ep0_stall(fd);
        continue;
      }
      response_data = NULL;
      response_length = event.ctrl.wLength;
    }
    if ((event.ctrl.bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD &&
        event.ctrl.bRequest == USB_REQ_SET_CONFIGURATION) {
      rv = configure_device(fd);
      if (rv < 0) {
        return rv;
      }
    }
    struct usb_raw_ep_io_data response;
    response.inner.ep = 0;
    response.inner.flags = 0;
    if (response_length > sizeof(response.data))
      response_length = 0;
    if (event.ctrl.wLength < response_length)
      response_length = event.ctrl.wLength;
    response.inner.length = response_length;
    if (response_data)
      memcpy(&response.data[0], response_data, response_length);
    else
      memset(&response.data[0], 0, response_length);
    if (event.ctrl.bRequestType & USB_DIR_IN) {
      rv = usb_raw_ep0_write(fd, (struct usb_raw_ep_io*)&response);
    } else {
      rv = usb_raw_ep0_read(fd, (struct usb_raw_ep_io*)&response);
    }
    if (rv < 0) {
      return rv;
    }
  }
  sleep_ms(200);
  return fd;
}

static volatile long syz_usb_connect(volatile long a0, volatile long a1,
                                     volatile long a2, volatile long a3)
{
  uint64_t speed = a0;
  uint64_t dev_len = a1;
  const char* dev = (const char*)a2;
  const struct vusb_connect_descriptors* descs =
      (const struct vusb_connect_descriptors*)a3;
  return syz_usb_connect_impl(speed, dev_len, dev, descs,
                              &lookup_connect_response_out_generic);
}

static volatile long syz_usb_control_io(volatile long a0, volatile long a1,
                                        volatile long a2)
{
  int fd = a0;
  const struct vusb_descriptors* descs = (const struct vusb_descriptors*)a1;
  const struct vusb_responses* resps = (const struct vusb_responses*)a2;
  struct usb_raw_control_event event;
  event.inner.type = 0;
  event.inner.length = USB_MAX_PACKET_SIZE;
  int rv = usb_raw_event_fetch(fd, (struct usb_raw_event*)&event);
  if (rv < 0) {
    return rv;
  }
  if (event.inner.type != USB_RAW_EVENT_CONTROL) {
    return -1;
  }
  char* response_data = NULL;
  uint32_t response_length = 0;
  if ((event.ctrl.bRequestType & USB_DIR_IN) && event.ctrl.wLength) {
    if (!lookup_control_response(descs, resps, &event.ctrl, &response_data,
                                 &response_length)) {
      usb_raw_ep0_stall(fd);
      return -1;
    }
  } else {
    if ((event.ctrl.bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD ||
        event.ctrl.bRequest == USB_REQ_SET_INTERFACE) {
      int iface_num = event.ctrl.wIndex;
      int alt_set = event.ctrl.wValue;
      int iface_index = lookup_interface(fd, iface_num, alt_set);
      if (iface_index < 0) {
      } else {
        set_interface(fd, iface_index);
      }
    }
    response_length = event.ctrl.wLength;
  }
  struct usb_raw_ep_io_data response;
  response.inner.ep = 0;
  response.inner.flags = 0;
  if (response_length > sizeof(response.data))
    response_length = 0;
  if (event.ctrl.wLength < response_length)
    response_length = event.ctrl.wLength;
  if ((event.ctrl.bRequestType & USB_DIR_IN) && !event.ctrl.wLength) {
    response_length = USB_MAX_PACKET_SIZE;
  }
  response.inner.length = response_length;
  if (response_data)
    memcpy(&response.data[0], response_data, response_length);
  else
    memset(&response.data[0], 0, response_length);
  if ((event.ctrl.bRequestType & USB_DIR_IN) && event.ctrl.wLength) {
    rv = usb_raw_ep0_write(fd, (struct usb_raw_ep_io*)&response);
  } else {
    rv = usb_raw_ep0_read(fd, (struct usb_raw_ep_io*)&response);
  }
  if (rv < 0) {
    return rv;
  }
  sleep_ms(200);
  return 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 setup_sysctl()
{
  int cad_pid = fork();
  if (cad_pid < 0)
    exit(1);
  if (cad_pid == 0) {
    for (;;)
      sleep(100);
  }
  char tmppid[32];
  snprintf(tmppid, sizeof(tmppid), "%d", cad_pid);
  struct {
    const char* name;
    const char* data;
  } files[] = {
      {"/sys/kernel/debug/x86/nmi_longest_ns", "10000000000"},
      {"/proc/sys/kernel/hung_task_check_interval_secs", "20"},
      {"/proc/sys/net/core/bpf_jit_kallsyms", "1"},
      {"/proc/sys/net/core/bpf_jit_harden", "0"},
      {"/proc/sys/kernel/kptr_restrict", "0"},
      {"/proc/sys/kernel/softlockup_all_cpu_backtrace", "1"},
      {"/proc/sys/fs/mount-max", "100"},
      {"/proc/sys/vm/oom_dump_tasks", "0"},
      {"/proc/sys/debug/exception-trace", "0"},
      {"/proc/sys/kernel/printk", "7 4 1 3"},
      {"/proc/sys/kernel/keys/gc_delay", "1"},
      {"/proc/sys/vm/oom_kill_allocating_task", "1"},
      {"/proc/sys/kernel/ctrl-alt-del", "0"},
      {"/proc/sys/kernel/cad_pid", tmppid},
  };
  for (size_t i = 0; i < sizeof(files) / sizeof(files[0]); i++) {
    if (!write_file(files[i].name, files[i].data)) {
    }
  }
  kill(cad_pid, SIGKILL);
  while (waitpid(cad_pid, NULL, 0) != cad_pid)
    ;
}

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)) {
  }
  *(uint8_t*)0x20000480 = 0x12;
  *(uint8_t*)0x20000481 = 1;
  *(uint16_t*)0x20000482 = 0;
  *(uint8_t*)0x20000484 = 2;
  *(uint8_t*)0x20000485 = 0;
  *(uint8_t*)0x20000486 = 0;
  *(uint8_t*)0x20000487 = 0x40;
  *(uint16_t*)0x20000488 = 0x525;
  *(uint16_t*)0x2000048a = 0xa4a1;
  *(uint16_t*)0x2000048c = 0x40;
  *(uint8_t*)0x2000048e = 1;
  *(uint8_t*)0x2000048f = 2;
  *(uint8_t*)0x20000490 = 3;
  *(uint8_t*)0x20000491 = 1;
  *(uint8_t*)0x20000492 = 9;
  *(uint8_t*)0x20000493 = 2;
  *(uint16_t*)0x20000494 = 0x5c;
  *(uint8_t*)0x20000496 = 2;
  *(uint8_t*)0x20000497 = 1;
  *(uint8_t*)0x20000498 = 0;
  *(uint8_t*)0x20000499 = 0;
  *(uint8_t*)0x2000049a = 0;
  *(uint8_t*)0x2000049b = 9;
  *(uint8_t*)0x2000049c = 4;
  *(uint8_t*)0x2000049d = 0;
  *(uint8_t*)0x2000049e = 0;
  *(uint8_t*)0x2000049f = 1;
  *(uint8_t*)0x200004a0 = 2;
  *(uint8_t*)0x200004a1 = 0xd;
  *(uint8_t*)0x200004a2 = 0;
  *(uint8_t*)0x200004a3 = 0;
  *(uint8_t*)0x200004a4 = 5;
  *(uint8_t*)0x200004a5 = 0x24;
  *(uint8_t*)0x200004a6 = 6;
  *(uint8_t*)0x200004a7 = 0;
  *(uint8_t*)0x200004a8 = 1;
  *(uint8_t*)0x200004a9 = 5;
  *(uint8_t*)0x200004aa = 0x24;
  *(uint8_t*)0x200004ab = 0;
  *(uint16_t*)0x200004ac = 0;
  *(uint8_t*)0x200004ae = 0xd;
  *(uint8_t*)0x200004af = 0x24;
  *(uint8_t*)0x200004b0 = 0xf;
  *(uint8_t*)0x200004b1 = 1;
  *(uint32_t*)0x200004b2 = 0;
  *(uint16_t*)0x200004b6 = 2;
  *(uint16_t*)0x200004b8 = 0;
  *(uint8_t*)0x200004ba = 0;
  *(uint8_t*)0x200004bb = 6;
  *(uint8_t*)0x200004bc = 0x24;
  *(uint8_t*)0x200004bd = 0x1a;
  *(uint16_t*)0x200004be = 0;
  *(uint8_t*)0x200004c0 = 0;
  *(uint8_t*)0x200004c1 = 9;
  *(uint8_t*)0x200004c2 = 5;
  *(uint8_t*)0x200004c3 = 0x81;
  *(uint8_t*)0x200004c4 = 3;
  *(uint16_t*)0x200004c5 = 0x200;
  *(uint8_t*)0x200004c7 = 0;
  *(uint8_t*)0x200004c8 = 0;
  *(uint8_t*)0x200004c9 = 0;
  *(uint8_t*)0x200004ca = 9;
  *(uint8_t*)0x200004cb = 4;
  *(uint8_t*)0x200004cc = 1;
  *(uint8_t*)0x200004cd = 0;
  *(uint8_t*)0x200004ce = 0;
  *(uint8_t*)0x200004cf = 2;
  *(uint8_t*)0x200004d0 = 0xd;
  *(uint8_t*)0x200004d1 = 0;
  *(uint8_t*)0x200004d2 = 0;
  *(uint8_t*)0x200004d3 = 9;
  *(uint8_t*)0x200004d4 = 4;
  *(uint8_t*)0x200004d5 = 1;
  *(uint8_t*)0x200004d6 = 1;
  *(uint8_t*)0x200004d7 = 2;
  *(uint8_t*)0x200004d8 = 2;
  *(uint8_t*)0x200004d9 = 0xd;
  *(uint8_t*)0x200004da = 0;
  *(uint8_t*)0x200004db = 0;
  *(uint8_t*)0x200004dc = 9;
  *(uint8_t*)0x200004dd = 5;
  *(uint8_t*)0x200004de = 0x82;
  *(uint8_t*)0x200004df = 2;
  *(uint16_t*)0x200004e0 = 0x200;
  *(uint8_t*)0x200004e2 = 0;
  *(uint8_t*)0x200004e3 = 0;
  *(uint8_t*)0x200004e4 = 0;
  *(uint8_t*)0x200004e5 = 9;
  *(uint8_t*)0x200004e6 = 5;
  *(uint8_t*)0x200004e7 = 3;
  *(uint8_t*)0x200004e8 = 2;
  *(uint16_t*)0x200004e9 = 0x200;
  *(uint8_t*)0x200004eb = 0;
  *(uint8_t*)0x200004ec = 0;
  *(uint8_t*)0x200004ed = 0;
  res = -1;
  res = syz_usb_connect(/*speed=*/0, /*dev_len=*/0x6e, /*dev=*/0x20000480,
                        /*conn_descs=*/0);
  if (res != -1)
    r[0] = res;
  syz_usb_control_io(/*fd=*/r[0], /*descs=*/0, /*resps=*/0);
  *(uint32_t*)0x20000540 = 0x101;
  *(uint32_t*)0x20000544 = 0xf3ee;
  *(uint32_t*)0x20000548 = 0xfffff8a7;
  *(uint32_t*)0x2000054c = 0x10001;
  *(uint32_t*)0x20000550 = 0xc;
  syscall(__NR_setsockopt, /*fd=*/-1, /*level=*/6, /*optname=*/0x1d,
          /*optval=*/0x20000540ul, /*optlen=*/0x14ul);
  memcpy((void*)0x20000540, "\x03\x00\x00\x00\x04\x00\x00\x00\x04\x00\x00\x00",
         12);
  syscall(__NR_bpf, /*cmd=*/0ul, /*arg=*/0x20000540ul, /*size=*/0x48ul);
  syscall(__NR_bpf, /*cmd=*/0ul, /*arg=*/0x20000540ul, /*size=*/0x48ul);
  syz_usb_control_io(/*fd=*/r[0], /*descs=*/0, /*resps=*/0);
  *(uint32_t*)0x20000340 = 0x44;
  *(uint64_t*)0x20000344 = 0;
  *(uint64_t*)0x2000034c = 0;
  *(uint64_t*)0x20000354 = 0;
  *(uint64_t*)0x2000035c = 0x20000200;
  *(uint8_t*)0x20000200 = 0x20;
  *(uint8_t*)0x20000201 = 0x80;
  *(uint32_t*)0x20000202 = 0x1c;
  *(uint16_t*)0x20000206 = 0x10;
  *(uint16_t*)0x20000208 = 0x10;
  *(uint32_t*)0x2000020a = 0x10;
  *(uint16_t*)0x2000020e = 0x10;
  *(uint16_t*)0x20000210 = 0x10;
  *(uint16_t*)0x20000212 = 0x10;
  *(uint16_t*)0x20000214 = 0x10;
  *(uint32_t*)0x20000216 = 0x10;
  *(uint16_t*)0x2000021a = 0x10;
  *(uint16_t*)0x2000021c = 0x10;
  *(uint16_t*)0x2000021e = 0x10;
  *(uint16_t*)0x20000220 = 0x10;
  *(uint64_t*)0x20000364 = 0;
  *(uint64_t*)0x2000036c = 0;
  *(uint64_t*)0x20000374 = 0;
  *(uint64_t*)0x2000037c = 0;
  syz_usb_control_io(/*fd=*/r[0], /*descs=*/0, /*resps=*/0x20000340);
  syz_usb_control_io(/*fd=*/r[0], /*descs=*/0, /*resps=*/0);
  *(uint32_t*)0x20000080 = 0x14;
  *(uint64_t*)0x20000084 = 0;
  *(uint64_t*)0x2000008c = 0x20000040;
  *(uint8_t*)0x20000040 = 0;
  *(uint8_t*)0x20000041 = 3;
  *(uint32_t*)0x20000042 = 0x1a;
  *(uint8_t*)0x20000046 = 0x1a;
  *(uint8_t*)0x20000047 = 3;
  *(uint64_t*)0x20000048 = htobe64(0x3400320034003200);
  *(uint64_t*)0x20000050 = htobe64(0x3400320034003200);
  *(uint64_t*)0x20000058 = htobe64(0x3400320034003200);
  syz_usb_control_io(/*fd=*/r[0], /*descs=*/0x20000080, /*resps=*/0);
}
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);
  setup_sysctl();
  const char* reason;
  (void)reason;
  for (procid = 0; procid < 6; procid++) {
    if (fork() == 0) {
      loop();
    }
  }
  sleep(1000000);
  return 0;
}

The kernel config is attached to this email. If you have any
questions, please contact us.

Best Regards,
Yue