cloud-hypervisor/fuzz/fuzz_targets/block.rs

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// Copyright 2018 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Copyright © 2022 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause
#![no_main]
use block_util::{async_io::DiskFile, raw_sync::RawFileDiskSync};
use libfuzzer_sys::fuzz_target;
use seccompiler::SeccompAction;
use std::ffi;
use std::fs::File;
use std::io;
use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
use std::path::PathBuf;
use std::sync::Arc;
use virtio_devices::{Block, VirtioDevice, VirtioInterrupt, VirtioInterruptType};
use virtio_queue::{Queue, QueueT};
use vm_memory::{bitmap::AtomicBitmap, Bytes, GuestAddress, GuestMemoryAtomic};
use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK};
type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>;
const QUEUE_DATA_SIZE: usize = 28;
const MEM_SIZE: usize = 256 * 1024 * 1024;
const QUEUE_SIZE: u16 = 16; // Max entries in the queue.
fuzz_target!(|bytes| {
if bytes.len() < QUEUE_DATA_SIZE || bytes.len() > (QUEUE_DATA_SIZE + MEM_SIZE) {
return;
}
let queue_data = &bytes[..QUEUE_DATA_SIZE];
let mem_bytes = &bytes[QUEUE_DATA_SIZE..];
// Create a virtio-block device backed by a synchronous raw file
let shm = memfd_create(&ffi::CString::new("fuzz").unwrap(), 0).unwrap();
let disk_file: File = unsafe { File::from_raw_fd(shm) };
let qcow_disk = Box::new(RawFileDiskSync::new(disk_file)) as Box<dyn DiskFile>;
let mut block = Block::new(
"tmp".to_owned(),
qcow_disk,
PathBuf::from(""),
false,
false,
2,
256,
SeccompAction::Allow,
None,
EventFd::new(EFD_NONBLOCK).unwrap(),
)
.unwrap();
// Setup the virt queue with the input bytes
let q = setup_virt_queue(queue_data.try_into().unwrap());
// Setup the guest memory with the input bytes
let mem = GuestMemoryMmap::from_ranges(&[(GuestAddress(0), MEM_SIZE)]).unwrap();
if mem.write_slice(mem_bytes, GuestAddress(0 as u64)).is_err() {
return;
}
let guest_memory = GuestMemoryAtomic::new(mem);
let evt = EventFd::new(0).unwrap();
let queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(evt.as_raw_fd())) };
// Kick the 'queue' event before activate the block device
queue_evt.write(1).unwrap();
block
.activate(
guest_memory,
Arc::new(NoopVirtioInterrupt {}),
vec![(0, q, evt)],
)
.ok();
// Wait for the events to finish and block device worker thread to return
block.reset();
});
fn memfd_create(name: &ffi::CStr, flags: u32) -> Result<RawFd, io::Error> {
let res = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags) };
if res < 0 {
Err(io::Error::last_os_error())
} else {
Ok(res as RawFd)
}
}
pub struct NoopVirtioInterrupt {}
impl VirtioInterrupt for NoopVirtioInterrupt {
fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> {
Ok(())
}
}
fn setup_virt_queue(bytes: &[u8; QUEUE_DATA_SIZE]) -> Queue {
let mut q = Queue::new(QUEUE_SIZE).unwrap();
q.set_next_avail(bytes[0] as u16); // 'u8' is enough given the 'QUEUE_SIZE' is small
q.set_next_used(bytes[1] as u16);
q.set_event_idx(bytes[2] % 2 != 0);
q.set_size(bytes[3] as u16 % QUEUE_SIZE);
q.set_desc_table_address(
Some(u32::from_le_bytes(bytes[4..8].try_into().unwrap())),
Some(u32::from_le_bytes(bytes[8..12].try_into().unwrap())),
);
q.set_avail_ring_address(
Some(u32::from_le_bytes(bytes[12..16].try_into().unwrap())),
Some(u32::from_le_bytes(bytes[16..20].try_into().unwrap())),
);
q.set_used_ring_address(
Some(u32::from_le_bytes(bytes[20..24].try_into().unwrap())),
Some(u32::from_le_bytes(bytes[24..28].try_into().unwrap())),
);
q.set_ready(true);
q
}