1 // Copyright © 2022 Intel Corporation 2 // 3 // SPDX-License-Identifier: Apache-2.0 4 5 #![no_main] 6 7 use libc::{MAP_NORESERVE, MAP_PRIVATE, PROT_READ, PROT_WRITE}; 8 use libfuzzer_sys::fuzz_target; 9 use seccompiler::SeccompAction; 10 use std::ffi; 11 use std::fs::File; 12 use std::io; 13 use std::os::unix::io::{AsRawFd, FromRawFd, RawFd}; 14 use std::sync::Arc; 15 use virtio_devices::{Pmem, UserspaceMapping, VirtioDevice, VirtioInterrupt, VirtioInterruptType}; 16 use virtio_queue::{Queue, QueueT}; 17 use vm_memory::guest_memory::FileOffset; 18 use vm_memory::{bitmap::AtomicBitmap, Bytes, GuestAddress, GuestMemoryAtomic, MmapRegion}; 19 use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK}; 20 21 type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>; 22 23 const QUEUE_DATA_SIZE: usize = 4; 24 const MEM_SIZE: usize = 256 * 1024 * 1024; 25 const PMEM_FILE_SIZE: usize = 128 * 1024 * 1024; 26 // Max entries in the queue. 27 const QUEUE_SIZE: u16 = 256; 28 // Guest physical address for descriptor table. 29 const DESC_TABLE_ADDR: u64 = 0; 30 const DESC_TABLE_SIZE: u64 = 16_u64 * QUEUE_SIZE as u64; 31 // Guest physical address for available ring 32 const AVAIL_RING_ADDR: u64 = DESC_TABLE_ADDR + DESC_TABLE_SIZE; 33 const AVAIL_RING_SIZE: u64 = 6_u64 + 2 * QUEUE_SIZE as u64; 34 // Guest physical address for used ring (requires to 4-bytes aligned) 35 const USED_RING_ADDR: u64 = (AVAIL_RING_ADDR + AVAIL_RING_SIZE + 3) & !3_u64; 36 37 fuzz_target!(|bytes| { 38 if bytes.len() < QUEUE_DATA_SIZE || bytes.len() > (QUEUE_DATA_SIZE + MEM_SIZE) { 39 return; 40 } 41 42 let mut pmem = create_dummy_pmem(); 43 let queue_data = &bytes[..QUEUE_DATA_SIZE]; 44 let mem_bytes = &bytes[QUEUE_DATA_SIZE..]; 45 46 // Setup the virt queue with the input bytes 47 let q = setup_virt_queue(queue_data.try_into().unwrap()); 48 49 // Setup the guest memory with the input bytes 50 let mem = GuestMemoryMmap::from_ranges(&[(GuestAddress(0), MEM_SIZE)]).unwrap(); 51 if mem.write_slice(mem_bytes, GuestAddress(0 as u64)).is_err() { 52 return; 53 } 54 let guest_memory = GuestMemoryAtomic::new(mem); 55 56 let evt = EventFd::new(0).unwrap(); 57 let queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(evt.as_raw_fd())) }; 58 59 // Kick the 'queue' event before activate the pmem device 60 queue_evt.write(1).unwrap(); 61 62 pmem.activate( 63 guest_memory, 64 Arc::new(NoopVirtioInterrupt {}), 65 vec![(0, q, evt)], 66 ) 67 .ok(); 68 69 // Wait for the events to finish and pmem device worker thread to return 70 pmem.wait_for_epoll_threads(); 71 }); 72 73 fn memfd_create_with_size(name: &ffi::CStr, flags: u32, size: usize) -> Result<RawFd, io::Error> { 74 let fd = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags) }; 75 if fd < 0 { 76 return Err(io::Error::last_os_error()); 77 } 78 79 let res = unsafe { libc::syscall(libc::SYS_ftruncate, fd, size) }; 80 if res < 0 { 81 return Err(io::Error::last_os_error()); 82 } 83 84 Ok(fd as RawFd) 85 } 86 87 pub struct NoopVirtioInterrupt {} 88 89 impl VirtioInterrupt for NoopVirtioInterrupt { 90 fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> { 91 Ok(()) 92 } 93 } 94 95 // Create a dummy virtio-pmem device for fuzzing purpose only 96 fn create_dummy_pmem() -> Pmem { 97 let shm = 98 memfd_create_with_size(&ffi::CString::new("fuzz").unwrap(), 0, PMEM_FILE_SIZE).unwrap(); 99 let file: File = unsafe { File::from_raw_fd(shm) }; 100 101 // The fuzzer is focusing on the virtio-pmem code that processes guest inputs (e.g. virt queues), 102 // so dummy mappings (both mmap and user mapping) does the job and is faster (using smaller amount of memory). 103 let dummy_mapping_size = 1; 104 let cloned_file = file.try_clone().unwrap(); 105 let dummy_mmap_region = MmapRegion::build( 106 Some(FileOffset::new(cloned_file, 0)), 107 dummy_mapping_size, 108 PROT_READ | PROT_WRITE, 109 MAP_NORESERVE | MAP_PRIVATE, 110 ) 111 .unwrap(); 112 let guest_addr = GuestAddress(0); 113 let dummy_user_mapping = UserspaceMapping { 114 host_addr: dummy_mmap_region.as_ptr() as u64, 115 mem_slot: 0, 116 addr: guest_addr, 117 len: dummy_mapping_size as u64, 118 mergeable: false, 119 }; 120 121 Pmem::new( 122 "tmp".to_owned(), 123 file, 124 guest_addr, 125 dummy_user_mapping, 126 dummy_mmap_region, 127 false, 128 SeccompAction::Allow, 129 EventFd::new(EFD_NONBLOCK).unwrap(), 130 None, 131 ) 132 .unwrap() 133 } 134 135 fn setup_virt_queue(bytes: &[u8; QUEUE_DATA_SIZE]) -> Queue { 136 let mut q = Queue::new(QUEUE_SIZE).unwrap(); 137 q.set_next_avail(bytes[0] as u16); // 'u8' is enough given the 'QUEUE_SIZE' is small 138 q.set_next_used(bytes[1] as u16); 139 q.set_event_idx(bytes[2] % 2 != 0); 140 q.set_size(bytes[3] as u16 % QUEUE_SIZE); 141 142 q.try_set_desc_table_address(GuestAddress(DESC_TABLE_ADDR)) 143 .unwrap(); 144 q.try_set_avail_ring_address(GuestAddress(AVAIL_RING_ADDR)) 145 .unwrap(); 146 q.try_set_used_ring_address(GuestAddress(USED_RING_ADDR)) 147 .unwrap(); 148 q.set_ready(true); 149 150 q 151 } 152