1 // Copyright © 2022 Intel Corporation 2 // 3 // SPDX-License-Identifier: Apache-2.0 4 5 #![no_main] 6 7 use libfuzzer_sys::fuzz_target; 8 use seccompiler::SeccompAction; 9 use std::os::unix::io::{AsRawFd, FromRawFd}; 10 use std::sync::Arc; 11 use virtio_devices::{VirtioDevice, VirtioInterrupt, VirtioInterruptType}; 12 use virtio_queue::{Queue, QueueT}; 13 use vm_memory::{bitmap::AtomicBitmap, Bytes, GuestAddress, GuestMemoryAtomic}; 14 use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK}; 15 16 type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>; 17 18 macro_rules! align { 19 ($n:expr, $align:expr) => {{ 20 (($n + $align - 1) / $align) * $align 21 }}; 22 } 23 24 const QUEUE_DATA_SIZE: usize = 4; 25 const MEM_SIZE: usize = 1 * 1024 * 1024; 26 27 // Max entries in the queue. 28 const QUEUE_SIZE: u16 = 256; 29 // Descriptor table alignment 30 const DESC_TABLE_ALIGN_SIZE: u64 = 16; 31 // Available ring alignment 32 const AVAIL_RING_ALIGN_SIZE: u64 = 2; 33 // Used ring alignment 34 const USED_RING_ALIGN_SIZE: u64 = 4; 35 // Descriptor table size 36 const DESC_TABLE_SIZE: u64 = 16_u64 * QUEUE_SIZE as u64; 37 // Available ring size 38 const AVAIL_RING_SIZE: u64 = 6_u64 + 2 * QUEUE_SIZE as u64; 39 // Used ring size 40 const USED_RING_SIZE: u64 = 6_u64 + 8 * QUEUE_SIZE as u64; 41 42 // Guest memory gap 43 const GUEST_MEM_GAP: u64 = 1 * 1024 * 1024; 44 // Guest physical address for descriptor table. 45 const DESC_TABLE_ADDR: u64 = align!(MEM_SIZE as u64 + GUEST_MEM_GAP, DESC_TABLE_ALIGN_SIZE); 46 // Guest physical address for available ring 47 const AVAIL_RING_ADDR: u64 = align!(DESC_TABLE_ADDR + DESC_TABLE_SIZE, AVAIL_RING_ALIGN_SIZE); 48 // Guest physical address for used ring 49 const USED_RING_ADDR: u64 = align!(AVAIL_RING_ADDR + AVAIL_RING_SIZE, USED_RING_ALIGN_SIZE); 50 // Virtio-queue size in bytes 51 const QUEUE_BYTES_SIZE: usize = (USED_RING_ADDR + USED_RING_SIZE - DESC_TABLE_ADDR) as usize; 52 53 fuzz_target!(|bytes| { 54 if bytes.len() < (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) 55 || bytes.len() > (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE + MEM_SIZE) 56 { 57 return; 58 } 59 60 let mut rng = virtio_devices::Rng::new( 61 "fuzzer_rng".to_owned(), 62 "/dev/urandom", 63 false, 64 SeccompAction::Allow, 65 EventFd::new(EFD_NONBLOCK).unwrap(), 66 None, 67 ) 68 .unwrap(); 69 70 let queue_data = &bytes[..QUEUE_DATA_SIZE]; 71 let queue_bytes = &bytes[QUEUE_DATA_SIZE..QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE]; 72 let mem_bytes = &bytes[QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE..]; 73 74 // Setup the virt queue with the input bytes 75 let q = setup_virt_queue(queue_data.try_into().unwrap()); 76 77 // Setup the guest memory with the input bytes 78 let mem = GuestMemoryMmap::from_ranges(&[ 79 (GuestAddress(0), MEM_SIZE), 80 (GuestAddress(DESC_TABLE_ADDR), QUEUE_BYTES_SIZE), 81 ]) 82 .unwrap(); 83 if mem 84 .write_slice(queue_bytes, GuestAddress(DESC_TABLE_ADDR)) 85 .is_err() 86 { 87 return; 88 } 89 if mem.write_slice(mem_bytes, GuestAddress(0 as u64)).is_err() { 90 return; 91 } 92 let guest_memory = GuestMemoryAtomic::new(mem); 93 94 let evt = EventFd::new(0).unwrap(); 95 let queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(evt.as_raw_fd())) }; 96 97 // Kick the 'queue' event before activate the rng device 98 queue_evt.write(1).unwrap(); 99 100 rng.activate( 101 guest_memory, 102 Arc::new(NoopVirtioInterrupt {}), 103 vec![(0, q, evt)], 104 ) 105 .ok(); 106 107 // Wait for the events to finish and rng device worker thread to return 108 rng.wait_for_epoll_threads(); 109 }); 110 111 pub struct NoopVirtioInterrupt {} 112 113 impl VirtioInterrupt for NoopVirtioInterrupt { 114 fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> { 115 Ok(()) 116 } 117 } 118 119 fn setup_virt_queue(bytes: &[u8; QUEUE_DATA_SIZE]) -> Queue { 120 let mut q = Queue::new(QUEUE_SIZE).unwrap(); 121 q.set_next_avail(bytes[0] as u16); // 'u8' is enough given the 'QUEUE_SIZE' is small 122 q.set_next_used(bytes[1] as u16); 123 q.set_event_idx(bytes[2] % 2 != 0); 124 q.set_size(bytes[3] as u16 % QUEUE_SIZE); 125 126 q.try_set_desc_table_address(GuestAddress(DESC_TABLE_ADDR)) 127 .unwrap(); 128 q.try_set_avail_ring_address(GuestAddress(AVAIL_RING_ADDR)) 129 .unwrap(); 130 q.try_set_used_ring_address(GuestAddress(USED_RING_ADDR)) 131 .unwrap(); 132 q.set_ready(true); 133 134 q 135 } 136