1 // Copyright © 2022 Intel Corporation 2 // 3 // SPDX-License-Identifier: Apache-2.0 4 5 #![no_main] 6 7 use std::os::unix::io::{AsRawFd, FromRawFd}; 8 use std::sync::Arc; 9 10 use libfuzzer_sys::{fuzz_target, Corpus}; 11 use seccompiler::SeccompAction; 12 use virtio_devices::{VirtioDevice, VirtioInterrupt, VirtioInterruptType}; 13 use virtio_queue::{Queue, QueueT}; 14 use vm_memory::bitmap::AtomicBitmap; 15 use vm_memory::{Bytes, GuestAddress, GuestMemoryAtomic}; 16 use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK}; 17 18 type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>; 19 20 const QUEUE_DATA_SIZE: usize = 4; 21 const MEM_SIZE: usize = 256 * 1024 * 1024; 22 // Max entries in the queue. 23 const QUEUE_SIZE: u16 = 256; 24 // Guest physical address for descriptor table. 25 const DESC_TABLE_ADDR: u64 = 0; 26 const DESC_TABLE_SIZE: u64 = 16_u64 * QUEUE_SIZE as u64; 27 // Guest physical address for available ring 28 const AVAIL_RING_ADDR: u64 = DESC_TABLE_ADDR + DESC_TABLE_SIZE; 29 const AVAIL_RING_SIZE: u64 = 6_u64 + 2 * QUEUE_SIZE as u64; 30 // Guest physical address for used ring (requires to 4-bytes aligned) 31 const USED_RING_ADDR: u64 = (AVAIL_RING_ADDR + AVAIL_RING_SIZE + 3) & !3_u64; 32 33 fuzz_target!(|bytes: &[u8]| -> Corpus { 34 if bytes.len() < QUEUE_DATA_SIZE || bytes.len() > (QUEUE_DATA_SIZE + MEM_SIZE) { 35 return Corpus::Reject; 36 } 37 38 let mut watchdog = virtio_devices::Watchdog::new( 39 "fuzzer_watchdog".to_owned(), 40 EventFd::new(EFD_NONBLOCK).unwrap(), 41 SeccompAction::Allow, 42 EventFd::new(EFD_NONBLOCK).unwrap(), 43 None, 44 ) 45 .unwrap(); 46 47 let queue_data = &bytes[..QUEUE_DATA_SIZE]; 48 let mem_bytes = &bytes[QUEUE_DATA_SIZE..]; 49 50 // Setup the virt queue with the input bytes 51 let q = setup_virt_queue(queue_data.try_into().unwrap()); 52 53 // Setup the guest memory with the input bytes 54 let mem = GuestMemoryMmap::from_ranges(&[(GuestAddress(0), MEM_SIZE)]).unwrap(); 55 if mem.write_slice(mem_bytes, GuestAddress(0 as u64)).is_err() { 56 return Corpus::Reject; 57 } 58 let guest_memory = GuestMemoryAtomic::new(mem); 59 60 let evt = EventFd::new(0).unwrap(); 61 let queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(evt.as_raw_fd())) }; 62 63 // Kick the 'queue' event before activate the watchdog device 64 queue_evt.write(1).unwrap(); 65 66 watchdog 67 .activate( 68 guest_memory, 69 Arc::new(NoopVirtioInterrupt {}), 70 vec![(0, q, evt)], 71 ) 72 .ok(); 73 74 // Wait for the events to finish and watchdog device worker thread to return 75 watchdog.wait_for_epoll_threads(); 76 77 Corpus::Keep 78 }); 79 80 pub struct NoopVirtioInterrupt {} 81 82 impl VirtioInterrupt for NoopVirtioInterrupt { 83 fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> { 84 Ok(()) 85 } 86 } 87 88 fn setup_virt_queue(bytes: &[u8; QUEUE_DATA_SIZE]) -> Queue { 89 let mut q = Queue::new(QUEUE_SIZE).unwrap(); 90 q.set_next_avail(bytes[0] as u16); // 'u8' is enough given the 'QUEUE_SIZE' is small 91 q.set_next_used(bytes[1] as u16); 92 q.set_event_idx(bytes[2] % 2 != 0); 93 q.set_size(bytes[3] as u16 % QUEUE_SIZE); 94 95 q.try_set_desc_table_address(GuestAddress(DESC_TABLE_ADDR)) 96 .unwrap(); 97 q.try_set_avail_ring_address(GuestAddress(AVAIL_RING_ADDR)) 98 .unwrap(); 99 q.try_set_used_ring_address(GuestAddress(USED_RING_ADDR)) 100 .unwrap(); 101 q.set_ready(true); 102 103 q 104 } 105