1 // Copyright 2018 The Chromium OS Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE-BSD-3-Clause file.
4 //
5 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
6
7 #![no_main]
8 use std::ffi;
9 use std::fs::File;
10 use std::io::{self, Cursor, Read, Seek, SeekFrom, Write};
11 use std::mem::size_of;
12 use std::os::unix::io::{FromRawFd, RawFd};
13
14 use block::qcow::{QcowFile, RawFile};
15 use libfuzzer_sys::{fuzz_target, Corpus};
16
17 // Take the first 64 bits of data as an address and the next 64 bits as data to
18 // store there. The rest of the data is used as a qcow image.
19 fuzz_target!(|bytes: &[u8]| -> Corpus {
20 if bytes.len() < 16 {
21 // Need an address and data, each are 8 bytes.
22 return Corpus::Reject;
23 }
24 let mut disk_image = Cursor::new(bytes);
25 let addr = read_u64(&mut disk_image);
26 let value = read_u64(&mut disk_image);
27 let shm = memfd_create(&ffi::CString::new("fuzz").unwrap(), 0).unwrap();
28 let mut disk_file: File = unsafe { File::from_raw_fd(shm) };
29 disk_file.write_all(&bytes[16..]).unwrap();
30 disk_file.seek(SeekFrom::Start(0)).unwrap();
31 if let Ok(mut qcow) = QcowFile::from(RawFile::new(disk_file, false)) {
32 if qcow.seek(SeekFrom::Start(addr)).is_ok() {
33 let _ = qcow.write_all(&value.to_le_bytes());
34 }
35 }
36
37 Corpus::Keep
38 });
39
read_u64<T: Read>(readable: &mut T) -> u6440 fn read_u64<T: Read>(readable: &mut T) -> u64 {
41 let mut buf = [0u8; size_of::<u64>()];
42 readable.read_exact(&mut buf[..]).unwrap();
43 u64::from_le_bytes(buf)
44 }
45
memfd_create(name: &ffi::CStr, flags: u32) -> Result<RawFd, io::Error>46 fn memfd_create(name: &ffi::CStr, flags: u32) -> Result<RawFd, io::Error> {
47 let res = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags) };
48
49 if res < 0 {
50 Err(io::Error::last_os_error())
51 } else {
52 Ok(res as RawFd)
53 }
54 }
55