diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml index 27040d7bc..f280d2807 100644 --- a/fuzz/Cargo.toml +++ b/fuzz/Cargo.toml @@ -57,6 +57,12 @@ path = "fuzz_targets/http_api.rs" test = false doc = false +[[bin]] +name = "pmem" +path = "fuzz_targets/pmem.rs" +test = false +doc = false + [[bin]] name = "qcow" path = "fuzz_targets/qcow.rs" diff --git a/fuzz/fuzz_targets/pmem.rs b/fuzz/fuzz_targets/pmem.rs new file mode 100644 index 000000000..79ad35b19 --- /dev/null +++ b/fuzz/fuzz_targets/pmem.rs @@ -0,0 +1,150 @@ +// Copyright © 2022 Intel Corporation +// +// SPDX-License-Identifier: Apache-2.0 + +#![no_main] + +use libc::{MAP_NORESERVE, MAP_PRIVATE, PROT_READ, PROT_WRITE}; +use libfuzzer_sys::fuzz_target; +use seccompiler::SeccompAction; +use std::ffi; +use std::fs::File; +use std::io; +use std::os::unix::io::{AsRawFd, FromRawFd, RawFd}; +use std::sync::Arc; +use virtio_devices::{Pmem, UserspaceMapping, VirtioDevice, VirtioInterrupt, VirtioInterruptType}; +use virtio_queue::{Queue, QueueT}; +use vm_memory::guest_memory::FileOffset; +use vm_memory::{bitmap::AtomicBitmap, Bytes, GuestAddress, GuestMemoryAtomic, MmapRegion}; +use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK}; + +type GuestMemoryMmap = vm_memory::GuestMemoryMmap; + +const QUEUE_DATA_SIZE: usize = 4; +const MEM_SIZE: usize = 256 * 1024 * 1024; +const PMEM_FILE_SIZE: usize = 128 * 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 pmem = create_dummy_pmem(); + 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 pmem device + queue_evt.write(1).unwrap(); + + pmem.activate( + guest_memory, + Arc::new(NoopVirtioInterrupt {}), + vec![(0, q, evt)], + ) + .ok(); + + // Wait for the events to finish and pmem device worker thread to return + pmem.reset(); +}); + +fn memfd_create_with_size(name: &ffi::CStr, flags: u32, size: usize) -> Result { + let fd = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags) }; + if fd < 0 { + return Err(io::Error::last_os_error()); + } + + let res = unsafe { libc::syscall(libc::SYS_ftruncate, fd, size) }; + if res < 0 { + return Err(io::Error::last_os_error()); + } + + Ok(fd as RawFd) +} + +pub struct NoopVirtioInterrupt {} + +impl VirtioInterrupt for NoopVirtioInterrupt { + fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> { + Ok(()) + } +} + +// Create a dummy virtio-pmem device for fuzzing purpose only +fn create_dummy_pmem() -> Pmem { + let shm = + memfd_create_with_size(&ffi::CString::new("fuzz").unwrap(), 0, PMEM_FILE_SIZE).unwrap(); + let file: File = unsafe { File::from_raw_fd(shm) }; + + // The fuzzer is focusing on the virtio-pmem code that processes guest inputs (e.g. virt queues), + // so dummy mappings (both mmap and user mapping) does the job and is faster (using smaller amount of memory). + let dummy_mapping_size = 1; + let cloned_file = file.try_clone().unwrap(); + let dummy_mmap_region = MmapRegion::build( + Some(FileOffset::new(cloned_file, 0)), + dummy_mapping_size, + PROT_READ | PROT_WRITE, + MAP_NORESERVE | MAP_PRIVATE, + ) + .unwrap(); + let guest_addr = GuestAddress(0); + let dummy_user_mapping = UserspaceMapping { + host_addr: dummy_mmap_region.as_ptr() as u64, + mem_slot: 0, + addr: guest_addr, + len: dummy_mapping_size as u64, + mergeable: false, + }; + + Pmem::new( + "tmp".to_owned(), + file, + guest_addr, + dummy_user_mapping, + dummy_mmap_region, + false, + SeccompAction::Allow, + EventFd::new(EFD_NONBLOCK).unwrap(), + ) + .unwrap() +} + +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 +}