KASAN: use-after-free Read in ext4_rename_dir_prepare

【标题描述】use-after-free Read in ext4_rename_dir_prepare
【环境信息】
硬件信息：不涉及
软件信息：5.10-OLK、openEuler-22.03-LTS
【问题复现步骤】
编译执行repo.c文件
出现概率(是否必现，概率性错误)大概率
【预期结果】
内核报错
【实际结果】
```
EXT4-fs (loop0): mounted filesystem without journal. Opts: ,errors=continue
```
【附件信息】
错误信息：
```
BUG: KASAN: use-after-free in ext4_rename_dir_prepare+0x181/0x210 fs/ext4/namei.c:3574
Read of size 4 at addr ffff888114c666ae by task syz-executor318/2335

CPU: 0 PID: 2335 Comm: syz-executor318 Not tainted 5.10.0+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:83 [inline]
 dump_stack+0x144/0x187 lib/dump_stack.c:124
 print_address_description+0x7d/0x630 mm/kasan/report.c:387
 __kasan_report+0x132/0x190 mm/kasan/report.c:547
 kasan_report+0x47/0x60 mm/kasan/report.c:564
 ext4_rename_dir_prepare+0x181/0x210 fs/ext4/namei.c:3574
 ext4_rename fs/ext4/namei.c:3865 [inline]
 ext4_rename2+0x171a/0x2530 fs/ext4/namei.c:4166
 vfs_rename+0x710/0x990 fs/namei.c:4307
 do_renameat2+0x5eb/0x9e0 fs/namei.c:4454
 __do_sys_renameat fs/namei.c:4495 [inline]
 __se_sys_renameat fs/namei.c:4492 [inline]
 __x64_sys_renameat+0x51/0x60 fs/namei.c:4492
 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x444f09
Code: 8d d2 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 5b d2 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffdf4b03c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000108
RAX: ffffffffffffffda RBX: 0000000000400280 RCX: 0000000000444f09
RDX: 0000000000000005 RSI: 0000000020000180 RDI: 0000000000000005
RBP: 00007fffdf4b03d0 R08: 0000000000000080 R09: 6c616b7a79732f2e
R10: 00000000200001c0 R11: 0000000000000246 R12: 00000000004025f0
R13: 0000000000402680 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:00000000ab15a76a refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x114c66
flags: 0x200000000000000()
raw: 0200000000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888114c66580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888114c66600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888114c66680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff

^
 ffff888114c66700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888114c66780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
```
repo.c
```
// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE

#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

#include <linux/loop.h>

#ifndef __NR_memfd_create
#define __NR_memfd_create 319
#endif

static unsigned long long procid;

static void use_temporary_dir(void)
{
  char tmpdir_template[] = "./syzkaller.XXXXXX";
  char* tmpdir = mkdtemp(tmpdir_template);
  if (!tmpdir)
    exit(1);
  if (chmod(tmpdir, 0777))
    exit(1);
  if (chdir(tmpdir))
    exit(1);
}

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;
}

struct fs_image_segment {
  void* data;
  uintptr_t size;
  uintptr_t offset;
};

#define IMAGE_MAX_SEGMENTS 4096
#define IMAGE_MAX_SIZE (129 << 20)

static unsigned long fs_image_segment_check(unsigned long size,
                                            unsigned long nsegs,
                                            struct fs_image_segment* segs)
{
  if (nsegs > IMAGE_MAX_SEGMENTS)
    nsegs = IMAGE_MAX_SEGMENTS;
  for (size_t i = 0; i < nsegs; i++) {
    if (segs[i].size > IMAGE_MAX_SIZE)
      segs[i].size = IMAGE_MAX_SIZE;
    segs[i].offset %= IMAGE_MAX_SIZE;
    if (segs[i].offset > IMAGE_MAX_SIZE - segs[i].size)
      segs[i].offset = IMAGE_MAX_SIZE - segs[i].size;
    if (size < segs[i].offset + segs[i].offset)
      size = segs[i].offset + segs[i].offset;
  }
  if (size > IMAGE_MAX_SIZE)
    size = IMAGE_MAX_SIZE;
  return size;
}
static int setup_loop_device(long unsigned size, long unsigned nsegs,
                             struct fs_image_segment* segs,
                             const char* loopname, int* memfd_p, int* loopfd_p)
{
  int err = 0, loopfd = -1;
  size = fs_image_segment_check(size, nsegs, segs);
  int memfd = syscall(__NR_memfd_create, "syzkaller", 0);
  if (memfd == -1) {
    err = errno;
    goto error;
  }
  if (ftruncate(memfd, size)) {
    err = errno;
    goto error_close_memfd;
  }
  for (size_t i = 0; i < nsegs; i++) {
    if (pwrite(memfd, segs[i].data, segs[i].size, segs[i].offset) < 0) {
    }
  }
  loopfd = open(loopname, O_RDWR);
  if (loopfd == -1) {
    err = errno;
    goto error_close_memfd;
  }
  if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
    if (errno != EBUSY) {
      err = errno;
      goto error_close_loop;
    }
    ioctl(loopfd, LOOP_CLR_FD, 0);
    usleep(1000);
    if (ioctl(loopfd, LOOP_SET_FD, memfd)) {
      err = errno;
      goto error_close_loop;
    }
  }
  *memfd_p = memfd;
  *loopfd_p = loopfd;
  return 0;

error_close_loop:
  close(loopfd);
error_close_memfd:
  close(memfd);
error:
  errno = err;
  return -1;
}

static long syz_mount_image(volatile long fsarg, volatile long dir,
                            volatile unsigned long size,
                            volatile unsigned long nsegs,
                            volatile long segments, volatile long flags,
                            volatile long optsarg)
{
  struct fs_image_segment* segs = (struct fs_image_segment*)segments;
  int res = -1, err = 0, loopfd = -1, memfd = -1, need_loop_device = !!segs;
  char* mount_opts = (char*)optsarg;
  char* target = (char*)dir;
  char* fs = (char*)fsarg;
  char* source = NULL;
  char loopname[64];
  if (need_loop_device) {
    memset(loopname, 0, sizeof(loopname));
    snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
    if (setup_loop_device(size, nsegs, segs, loopname, &memfd, &loopfd) == -1)
      return -1;
    source = loopname;
  }
  mkdir(target, 0777);
  char opts[256];
  memset(opts, 0, sizeof(opts));
  if (strlen(mount_opts) > (sizeof(opts) - 32)) {
  }
  strncpy(opts, mount_opts, sizeof(opts) - 32);
  if (strcmp(fs, "iso9660") == 0) {
    flags |= MS_RDONLY;
  } else if (strncmp(fs, "ext", 3) == 0) {
    if (strstr(opts, "errors=panic") || strstr(opts, "errors=remount-ro") == 0)
      strcat(opts, ",errors=continue");
  } else if (strcmp(fs, "xfs") == 0) {
    strcat(opts, ",nouuid");
  }
  res = mount(source, target, fs, flags, opts);
  if (res == -1) {
    err = errno;
    goto error_clear_loop;
  }
  res = open(target, O_RDONLY | O_DIRECTORY);
  if (res == -1) {
    err = errno;
  }

error_clear_loop:
  if (need_loop_device) {
    ioctl(loopfd, LOOP_CLR_FD, 0);
    close(loopfd);
    close(memfd);
  }
  errno = err;
  return res;
}

static void setup_sysctl()
{
  char mypid[32];
  snprintf(mypid, sizeof(mypid), "%d", getpid());
  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/net/ipv4/ping_group_range", "0 65535"},
      {"/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", mypid},
  };
  for (size_t i = 0; i < sizeof(files) / sizeof(files[0]); i++) {
    if (!write_file(files[i].name, files[i].data))
      printf("write to %s failed: %s\n", files[i].name, strerror(errno));
  }
}

uint64_t r[1] = {0xffffffffffffffff};

int main(void)
{
  syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
  syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
  syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
  setup_sysctl();
  use_temporary_dir();
  intptr_t res = 0;
  memcpy((void*)0x20000000, "ext4\000", 5);
  memcpy((void*)0x20000100, "./file0\000", 8);
  *(uint64_t*)0x20000200 = 0x20010000;
  memcpy((void*)0x20010000,
         "\x20\x00\x00\x00\x00\x02\x00\x00\x19\x00\x00\x00\x60\x01\x00\x00\x0f"
         "\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x05\x00\x00\x00\x00\x00"
         "\x04\x00\x00\x40\x00\x00\x20\x00\x00\x00\xd4\xf4\x65\x5f\xd4\xf4\x65"
         "\x5f\x01\x00\xff\xff\x53\xef\x01\x00\x01\x00\x00\x00\xd3\xf4\x65\x5f"
         "\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x0b"
         "\x00\x00\x00\x00\x01\x00\x00\x08\x00\x00\x00\xd2\x42\x01\x00\x12\x03",
         102);
  *(uint64_t*)0x20000208 = 0x66;
  *(uint64_t*)0x20000210 = 0x400;
  *(uint64_t*)0x20000218 = 0x20010100;
  memcpy((void*)0x20010100,
         "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x76\xa3\x4e\x3f\x63"
         "\xe5\x4d\xbc\x89\x55\xdd\x45\x88\x8f\x61\x06\x01\x00\x40",
         31);
  *(uint64_t*)0x20000220 = 0x1f;
  *(uint64_t*)0x20000228 = 0x4e0;
  *(uint64_t*)0x20000230 = 0x20010400;
  memcpy((void*)0x20010400,
         "\x02\x00\x00\x00\x03\x00\x00\x00\x04\x00\x00\x00\x16\x00\x0f\x00\x03"
         "\x00\x04\x00\x00\x00\x00\x00\x00\x00\x00\x00\x0f\x00\xc5\xd7",
         32);
  *(uint64_t*)0x20000238 = 0x20;
  *(uint64_t*)0x20000240 = 0x800;
  *(uint64_t*)0x20000248 = 0x20011600;
  memcpy((void*)0x20011600,
         "\xed\x41\x00\x00\x00\x08\x00\x00\xd3\xf4\x65\x5f\xd4\xf4\x65\x5f\xd4"
         "\xf4\x65\x5f\x00\x00\x00\x00\x00\x00\x04\x00\x40\x00\x00\x00\x00\x00"
         "\x08\x00\x05\x00\x00\x00\x0a\xf3\x01\x00\x04\x00\x00\x00\x00\x00\x00"
         "\x00\x00\x00\x00\x00\x01\x00\x00\x00\x10",
         61);
  *(uint64_t*)0x20000250 = 0x3d;
  *(uint64_t*)0x20000258 = 0x2100;
  *(uint64_t*)0x20000260 = 0x20000140;
  memcpy((void*)0x20000140,
         "\xed\x41\x00\x00\x00\x08\x00\x00\xd4\xf4\x65\x5f\xd4\xf4\x65\x5f\xd4"
         "\xf4\x65\x5f\x00\x00\x00\x00\x00\x00\x02\x00\x40\x00\x00\x00\x00\x00"
         "\x08\x00\x03\x00\x00\x00\x0a\xf3\x01\x00\x04\x00\x00\x00\x00\x00\x00"
         "\x00\x00\x00\x00\x00\x01\x00\x00\x00\x50",
         61);
  *(uint64_t*)0x20000268 = 0x3d;
  *(uint64_t*)0x20000270 = 0x2b00;
  *(uint64_t*)0x20000278 = 0x20012400;
  memcpy((void*)0x20012400,
         "\x02\x00\x00\x00\x0c\x00\x01\x02\x2e\x00\x00\x00\x02\x00\x00\x00\x0c"
         "\x00\x02\x02\x2e\x2e\x00\x00\x0b\x00\x00\x00\x14\x00\x0a\x02\x6c\x6f"
         "\x73\x74\x2b\x66\x6f\x75\x6e\x64\x00\x00\x0c\x00\x00\x00\x10\x00\x05"
         "\x02\x66\x69\x6c\x65\x30",
         57);
  *(uint64_t*)0x20000280 = 0x39;
  *(uint64_t*)0x20000288 = 0x8000;
  *(uint64_t*)0x20000290 = 0x20013900;
  memcpy((void*)0x20013900,
         "\x0c\x00\x00\xea\xae\x86\x70\x2f\x43\xde\x0b\x00\x02", 13);
  *(uint64_t*)0x20000298 = 0xd;
  *(uint64_t*)0x200002a0 = 0x28000;
  *(uint8_t*)0x20000080 = 0;
  res = -1;
  res = syz_mount_image(0x20000000, 0x20000100, 0x100000, 7, 0x20000200, 0x80,
                        0x20000080);
  if (res != -1)
    r[0] = res;
  memcpy((void*)0x20000180, "./file0\000", 8);
  memcpy((void*)0x200001c0, "./file1\000", 8);
  syscall(__NR_renameat, r[0], 0x20000180ul, r[0], 0x200001c0ul);
  return 0;
}
```

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