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https://github.com/cloud-hypervisor/cloud-hypervisor.git
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cf55698168
Fuzzing QcowFile, which is not used by virtio-block, is less helpful than using the abstraction that is. Ensure we cover at least the same functionality as before. Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Rob Bradford <rbradford@meta.com>
85 lines
3.0 KiB
Rust
85 lines
3.0 KiB
Rust
// Copyright 2018 The Chromium OS Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE-BSD-3-Clause file.
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//
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// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
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#![no_main]
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use std::ffi;
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use std::fs::File;
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use std::io::{self, Cursor, Read, Seek, SeekFrom, Write};
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use std::mem::size_of;
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use std::os::unix::io::{FromRawFd, RawFd};
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use std::sync::Arc;
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use block::async_io::GuestMemoryTarget;
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use block::disk_file::AsyncDiskFile;
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use block::formats::qcow::QcowDisk;
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use libfuzzer_sys::{fuzz_target, Corpus};
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use vm_memory::{Bytes, GuestAddress, GuestMemoryMmap};
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// Take the first 64 bits of data as an address and the next 64 bits as data to
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// store there. The rest of the data is used as a qcow image.
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fuzz_target!(|bytes: &[u8]| -> Corpus {
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if bytes.len() < 16 {
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// Need an address and data, each are 8 bytes.
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return Corpus::Reject;
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}
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let mut disk_image = Cursor::new(bytes);
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let addr = read_u64(&mut disk_image);
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let value = read_u64(&mut disk_image);
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let shm = memfd_create(&ffi::CString::new("fuzz").unwrap(), 0).unwrap();
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let mut disk_file: File = unsafe { File::from_raw_fd(shm) };
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disk_file.write_all(&bytes[16..]).unwrap();
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disk_file.seek(SeekFrom::Start(0)).unwrap();
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let Ok(disk) = QcowDisk::new(disk_file, false, false, true, false) else {
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return Corpus::Keep;
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};
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let Ok(mut async_io) = disk.create_async_io(1) else {
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return Corpus::Keep;
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};
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let len = size_of::<u64>();
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let Ok(mem) = GuestMemoryMmap::<()>::from_ranges(&[(GuestAddress(0), len)]) else {
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return Corpus::Keep;
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};
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let mem = Arc::new(mem);
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let _ = mem.write_slice(&value.to_le_bytes(), GuestAddress(0));
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let range = [(GuestAddress(0), len as u32)];
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let off = addr as libc::off_t;
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if let Ok(target) = GuestMemoryTarget::new(Arc::clone(&mem), &range) {
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let _ = async_io.write_from_memory(off, target, 0);
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while async_io.next_completed_request().is_some() {}
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}
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if let Ok(target) = GuestMemoryTarget::new(Arc::clone(&mem), &range) {
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let _ = async_io.read_to_memory(off, target, 1);
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while async_io.next_completed_request().is_some() {}
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}
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let _ = async_io.write_zeroes(addr, len as u64, 2);
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while async_io.next_completed_request().is_some() {}
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let _ = async_io.punch_hole(addr, len as u64, 3);
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while async_io.next_completed_request().is_some() {}
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let _ = async_io.fsync(Some(4));
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while async_io.next_completed_request().is_some() {}
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Corpus::Keep
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});
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fn read_u64<T: Read>(readable: &mut T) -> u64 {
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let mut buf = [0u8; size_of::<u64>()];
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readable.read_exact(&mut buf[..]).unwrap();
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u64::from_le_bytes(buf)
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}
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fn memfd_create(name: &ffi::CStr, flags: u32) -> Result<RawFd, io::Error> {
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let res = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags) };
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if res < 0 {
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Err(io::Error::last_os_error())
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} else {
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Ok(res as RawFd)
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}
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}
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