syzkaller-repros/linux/00965426fe7ceec1fd2d8756770d4c7c3cacdc4b.c

// KASAN: use-after-free Read in blkdev_get
// https://syzkaller.appspot.com/bug?id=00965426fe7ceec1fd2d8756770d4c7c3cacdc4b
// status:open
// autogenerated by syzkaller (http://github.com/google/syzkaller)

#define _GNU_SOURCE
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/loop.h>
#include <stdint.h>
#include <stdio.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>

extern unsigned long long procid;

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

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

#define SYZ_memfd_create 319

static uintptr_t syz_mount_image(uintptr_t fsarg, uintptr_t dir, uintptr_t size,
                                 uintptr_t nsegs, uintptr_t segments,
                                 uintptr_t flags, uintptr_t optsarg)
{
  char loopname[64], fs[32], opts[256];
  int loopfd, err = 0, res = -1;
  uintptr_t i;
  struct fs_image_segment* segs = (struct fs_image_segment*)segments;

  if (nsegs > IMAGE_MAX_SEGMENTS)
    nsegs = IMAGE_MAX_SEGMENTS;
  for (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;
  int memfd = syscall(SYZ_memfd_create, "syz_mount_image", 0);
  if (memfd == -1) {
    err = errno;
    goto error;
  }
  if (ftruncate(memfd, size)) {
    err = errno;
    goto error_close_memfd;
  }
  for (i = 0; i < nsegs; i++) {
    if (pwrite(memfd, segs[i].data, segs[i].size, segs[i].offset) < 0) {
    }
  }
  snprintf(loopname, sizeof(loopname), "/dev/loop%llu", procid);
  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;
    }
  }
  mkdir((char*)dir, 0777);
  memset(fs, 0, sizeof(fs));
  strncpy(fs, (char*)fsarg, sizeof(fs) - 1);
  memset(opts, 0, sizeof(opts));
  strncpy(opts, (char*)optsarg, 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");
  }
  if (mount(loopname, (char*)dir, fs, flags, opts)) {
    err = errno;
    goto error_clear_loop;
  }
  res = 0;
error_clear_loop:
  ioctl(loopfd, LOOP_CLR_FD, 0);
error_close_loop:
  close(loopfd);
error_close_memfd:
  close(memfd);
error:
  errno = err;
  return res;
}

static void execute_one();
extern unsigned long long procid;

void loop()
{
  while (1) {
    execute_one();
  }
}

unsigned long long procid;
void execute_one()
{
  memcpy((void*)0x20000000, "reiserfs", 9);
  memcpy((void*)0x20000100, "./fiue0", 8);
  *(uint64_t*)0x20000200 = 0x20000240;
  memcpy((void*)0x20000240,
         "\x00\x08\x00\x00\xec\x05\x00\x00\x6d\x8a\x2b\x00\x12\x00\x00\x00\x08"
         "\x08\x00\x00\xb9\x02\x00\x00\x00\x01\x00\x00\x84\x81\x1f\x4c\xe1\x00"
         "\x00\x00\x1e\x00\x00\x00\x00\x00\x00\x00\x00\x10\xec\x03\x02\xe5\xfb"
         "\x00\x52\x65\x49\x73\x45\x72\x33\x46\x73",
         61);
  *(uint64_t*)0x20000208 = 0x3d;
  *(uint64_t*)0x20000210 = 0x10000;
  *(uint8_t*)0x20013900 = 0;
  syz_mount_image(0x20000000, 0x20000100, 0x400000000000000, 1, 0x20000200, 0,
                  0x20013900);
}

int main()
{
  syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
  for (procid = 0; procid < 8; procid++) {
    if (fork() == 0) {
      for (;;) {
        loop();
      }
    }
  }
  sleep(1000000);
  return 0;
}