cloud-hypervisor/fuzz/fuzz_targets/watchdog.rs

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// Copyright © 2022 Intel Corporation
//
// SPDX-License-Identifier: Apache-2.0
#![no_main]
use std::os::unix::io::{AsRawFd, FromRawFd};
use std::sync::Arc;
use libfuzzer_sys::fuzz_target;
use seccompiler::SeccompAction;
use virtio_devices::{VirtioDevice, VirtioInterrupt, VirtioInterruptType};
use virtio_queue::{Queue, QueueT};
use vm_memory::bitmap::AtomicBitmap;
use vm_memory::{Bytes, GuestAddress, GuestMemoryAtomic};
use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK};
type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>;
const QUEUE_DATA_SIZE: usize = 4;
const MEM_SIZE: usize = 256 * 1024 * 1024;
// Max entries in the queue.
const QUEUE_SIZE: u16 = 256;
// Guest physical address for descriptor table.
const DESC_TABLE_ADDR: u64 = 0;
const DESC_TABLE_SIZE: u64 = 16_u64 * QUEUE_SIZE as u64;
// Guest physical address for available ring
const AVAIL_RING_ADDR: u64 = DESC_TABLE_ADDR + DESC_TABLE_SIZE;
const AVAIL_RING_SIZE: u64 = 6_u64 + 2 * QUEUE_SIZE as u64;
// Guest physical address for used ring (requires to 4-bytes aligned)
const USED_RING_ADDR: u64 = (AVAIL_RING_ADDR + AVAIL_RING_SIZE + 3) & !3_u64;
fuzz_target!(|bytes| {
if bytes.len() < QUEUE_DATA_SIZE || bytes.len() > (QUEUE_DATA_SIZE + MEM_SIZE) {
return;
}
let mut watchdog = virtio_devices::Watchdog::new(
"fuzzer_watchdog".to_owned(),
EventFd::new(EFD_NONBLOCK).unwrap(),
SeccompAction::Allow,
EventFd::new(EFD_NONBLOCK).unwrap(),
None,
)
.unwrap();
let queue_data = &bytes[..QUEUE_DATA_SIZE];
let mem_bytes = &bytes[QUEUE_DATA_SIZE..];
// 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 watchdog device
queue_evt.write(1).unwrap();
watchdog
.activate(
guest_memory,
Arc::new(NoopVirtioInterrupt {}),
vec![(0, q, evt)],
)
.ok();
// Wait for the events to finish and watchdog device worker thread to return
watchdog.wait_for_epoll_threads();
});
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.try_set_desc_table_address(GuestAddress(DESC_TABLE_ADDR))
.unwrap();
q.try_set_avail_ring_address(GuestAddress(AVAIL_RING_ADDR))
.unwrap();
q.try_set_used_ring_address(GuestAddress(USED_RING_ADDR))
.unwrap();
q.set_ready(true);
q
}