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 file. 4 // 5 // Copyright © 2022 Intel Corporation 6 // 7 // SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause 8 9 #![no_main] 10 11 use block::{async_io::DiskFile, raw_sync::RawFileDiskSync}; 12 use libfuzzer_sys::fuzz_target; 13 use seccompiler::SeccompAction; 14 use std::ffi; 15 use std::fs::File; 16 use std::io; 17 use std::os::unix::io::{AsRawFd, FromRawFd, RawFd}; 18 use std::path::PathBuf; 19 use std::sync::Arc; 20 use virtio_devices::{Block, VirtioDevice, VirtioInterrupt, VirtioInterruptType}; 21 use virtio_queue::{Queue, QueueT}; 22 use vm_memory::{bitmap::AtomicBitmap, Bytes, GuestAddress, GuestMemoryAtomic}; 23 use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK}; 24 25 type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>; 26 27 const QUEUE_DATA_SIZE: usize = 4; 28 const MEM_SIZE: usize = 256 * 1024 * 1024; 29 // Max entries in the queue. 30 const QUEUE_SIZE: u16 = 256; 31 // Guest physical address for descriptor table. 32 const DESC_TABLE_ADDR: u64 = 0; 33 const DESC_TABLE_SIZE: u64 = 16_u64 * QUEUE_SIZE as u64; 34 // Guest physical address for available ring 35 const AVAIL_RING_ADDR: u64 = DESC_TABLE_ADDR + DESC_TABLE_SIZE; 36 const AVAIL_RING_SIZE: u64 = 6_u64 + 2 * QUEUE_SIZE as u64; 37 // Guest physical address for used ring (requires to 4-bytes aligned) 38 const USED_RING_ADDR: u64 = (AVAIL_RING_ADDR + AVAIL_RING_SIZE + 3) & !3_u64; 39 40 fuzz_target!(|bytes| { 41 if bytes.len() < QUEUE_DATA_SIZE || bytes.len() > (QUEUE_DATA_SIZE + MEM_SIZE) { 42 return; 43 } 44 45 let queue_data = &bytes[..QUEUE_DATA_SIZE]; 46 let mem_bytes = &bytes[QUEUE_DATA_SIZE..]; 47 48 // Create a virtio-block device backed by a synchronous raw file 49 let shm = memfd_create(&ffi::CString::new("fuzz").unwrap(), 0).unwrap(); 50 let disk_file: File = unsafe { File::from_raw_fd(shm) }; 51 let qcow_disk = Box::new(RawFileDiskSync::new(disk_file)) as Box<dyn DiskFile>; 52 let mut block = Block::new( 53 "tmp".to_owned(), 54 qcow_disk, 55 PathBuf::from(""), 56 false, 57 false, 58 2, 59 256, 60 SeccompAction::Allow, 61 None, 62 EventFd::new(EFD_NONBLOCK).unwrap(), 63 None, 64 ) 65 .unwrap(); 66 67 // Setup the virt queue with the input bytes 68 let q = setup_virt_queue(queue_data.try_into().unwrap()); 69 70 // Setup the guest memory with the input bytes 71 let mem = GuestMemoryMmap::from_ranges(&[(GuestAddress(0), MEM_SIZE)]).unwrap(); 72 if mem.write_slice(mem_bytes, GuestAddress(0 as u64)).is_err() { 73 return; 74 } 75 let guest_memory = GuestMemoryAtomic::new(mem); 76 77 let evt = EventFd::new(0).unwrap(); 78 let queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(evt.as_raw_fd())) }; 79 80 // Kick the 'queue' event before activate the block device 81 queue_evt.write(1).unwrap(); 82 83 block 84 .activate( 85 guest_memory, 86 Arc::new(NoopVirtioInterrupt {}), 87 vec![(0, q, evt)], 88 ) 89 .ok(); 90 91 // Wait for the events to finish and block device worker thread to return 92 block.wait_for_epoll_threads(); 93 }); 94 95 fn memfd_create(name: &ffi::CStr, flags: u32) -> Result<RawFd, io::Error> { 96 let res = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags) }; 97 98 if res < 0 { 99 Err(io::Error::last_os_error()) 100 } else { 101 Ok(res as RawFd) 102 } 103 } 104 105 pub struct NoopVirtioInterrupt {} 106 107 impl VirtioInterrupt for NoopVirtioInterrupt { 108 fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> { 109 Ok(()) 110 } 111 } 112 113 fn setup_virt_queue(bytes: &[u8; QUEUE_DATA_SIZE]) -> Queue { 114 let mut q = Queue::new(QUEUE_SIZE).unwrap(); 115 q.set_next_avail(bytes[0] as u16); // 'u8' is enough given the 'QUEUE_SIZE' is small 116 q.set_next_used(bytes[1] as u16); 117 q.set_event_idx(bytes[2] % 2 != 0); 118 q.set_size(bytes[3] as u16 % QUEUE_SIZE); 119 120 q.try_set_desc_table_address(GuestAddress(DESC_TABLE_ADDR)) 121 .unwrap(); 122 q.try_set_avail_ring_address(GuestAddress(AVAIL_RING_ADDR)) 123 .unwrap(); 124 q.try_set_used_ring_address(GuestAddress(USED_RING_ADDR)) 125 .unwrap(); 126 q.set_ready(true); 127 128 q 129 } 130