fuzz: Add fuzzer for virtio-console

Signed-off-by: Bo Chen <chen.bo@intel.com>

fuzz/Cargo.toml

@@ -58,6 +58,12 @@ path = "fuzz_targets/cmos.rs"
 test = false
 doc = false
 
+[[bin]]
+name = "console"
+path = "fuzz_targets/console.rs"
+test = false
+doc = false
+
 [[bin]]
 name = "http_api"
 path = "fuzz_targets/http_api.rs"

fuzz/fuzz_targets/console.rs

@@ -0,0 +1,194 @@
+// Copyright © 2022 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+use seccompiler::SeccompAction;
+use std::fs::File;
+use std::io::Write;
+use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
+use std::sync::Arc;
+use virtio_devices::{VirtioDevice, VirtioInterrupt, VirtioInterruptType};
+use virtio_queue::{Queue, QueueT};
+use vm_memory::{bitmap::AtomicBitmap, Bytes, GuestAddress, GuestMemoryAtomic};
+use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK};
+
+type GuestMemoryMmap = vm_memory::GuestMemoryMmap<AtomicBitmap>;
+
+macro_rules! align {
+    ($n:expr, $align:expr) => {{
+        (($n + $align - 1) / $align) * $align
+    }};
+}
+
+const CONSOLE_INPUT_SIZE: usize = 128;
+const QUEUE_DATA_SIZE: usize = 4;
+const MEM_SIZE: usize = 32 * 1024 * 1024;
+// Guest memory gap
+const GUEST_MEM_GAP: u64 = 1 * 1024 * 1024;
+// Guest physical address for the first virt queue
+const BASE_VIRT_QUEUE_ADDR: u64 = MEM_SIZE as u64 + GUEST_MEM_GAP;
+// Number of queues
+const QUEUE_NUM: usize = 2;
+// Max entries in the queue.
+const QUEUE_SIZE: u16 = 256;
+// Descriptor table alignment
+const DESC_TABLE_ALIGN_SIZE: u64 = 16;
+// Used ring alignment
+const USED_RING_ALIGN_SIZE: u64 = 4;
+// Descriptor table size
+const DESC_TABLE_SIZE: u64 = 16_u64 * QUEUE_SIZE as u64;
+// Available ring size
+const AVAIL_RING_SIZE: u64 = 6_u64 + 2 * QUEUE_SIZE as u64;
+// Padding size before used ring
+const PADDING_SIZE: u64 = align!(AVAIL_RING_SIZE, USED_RING_ALIGN_SIZE) - AVAIL_RING_SIZE;
+// Used ring size
+const USED_RING_SIZE: u64 = 6_u64 + 8 * QUEUE_SIZE as u64;
+// Virtio-queue size in bytes
+const QUEUE_BYTES_SIZE: usize = align!(
+    DESC_TABLE_SIZE + AVAIL_RING_SIZE + PADDING_SIZE + USED_RING_SIZE,
+    DESC_TABLE_ALIGN_SIZE
+) as usize;
+
+fuzz_target!(|bytes| {
+    if bytes.len() < (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) * QUEUE_NUM + CONSOLE_INPUT_SIZE
+        || bytes.len()
+            > (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) * QUEUE_NUM + CONSOLE_INPUT_SIZE + MEM_SIZE
+    {
+        return;
+    }
+
+    let (pipe_rx, mut pipe_tx) = create_pipe().unwrap();
+    let output = unsafe {
+        File::from_raw_fd(
+            memfd_create(&std::ffi::CString::new("fuzz_console_output").unwrap()).unwrap(),
+        )
+    };
+    let endpoint = virtio_devices::Endpoint::FilePair(output, pipe_rx);
+
+    let (mut console, _) = virtio_devices::Console::new(
+        "fuzzer_console".to_owned(),
+        endpoint,
+        None,  // resize_pipe
+        false, // iommu
+        SeccompAction::Allow,
+        EventFd::new(EFD_NONBLOCK).unwrap(),
+        None,
+    )
+    .unwrap();
+
+    let console_input_bytes = &bytes[..CONSOLE_INPUT_SIZE];
+    let queue_data = &bytes[CONSOLE_INPUT_SIZE..CONSOLE_INPUT_SIZE + QUEUE_DATA_SIZE * QUEUE_NUM];
+    let queue_bytes = &bytes[CONSOLE_INPUT_SIZE + QUEUE_DATA_SIZE * QUEUE_NUM
+        ..CONSOLE_INPUT_SIZE + (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) * QUEUE_NUM];
+    let mem_bytes = &bytes[CONSOLE_INPUT_SIZE + (QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE) * QUEUE_NUM..];
+
+    // Setup the virt queues with the input bytes
+    let mut queues = setup_virt_queues(
+        &[
+            &queue_data[..QUEUE_DATA_SIZE].try_into().unwrap(),
+            &queue_data[QUEUE_DATA_SIZE..QUEUE_DATA_SIZE * 2]
+                .try_into()
+                .unwrap(),
+        ],
+        BASE_VIRT_QUEUE_ADDR,
+    );
+
+    // Setup the guest memory with the input bytes
+    let mem = GuestMemoryMmap::from_ranges(&[
+        (GuestAddress(0), MEM_SIZE),
+        (GuestAddress(BASE_VIRT_QUEUE_ADDR), queue_bytes.len()),
+    ])
+    .unwrap();
+    if mem
+        .write_slice(queue_bytes, GuestAddress(BASE_VIRT_QUEUE_ADDR))
+        .is_err()
+    {
+        return;
+    }
+    if mem.write_slice(mem_bytes, GuestAddress(0 as u64)).is_err() {
+        return;
+    }
+    let guest_memory = GuestMemoryAtomic::new(mem);
+
+    let input_queue = queues.remove(0);
+    let input_evt = EventFd::new(0).unwrap();
+    let input_queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(input_evt.as_raw_fd())) };
+    let output_queue = queues.remove(0);
+    let output_evt = EventFd::new(0).unwrap();
+    let output_queue_evt = unsafe { EventFd::from_raw_fd(libc::dup(output_evt.as_raw_fd())) };
+
+    // Kick the 'queue' events and endpoint event before activate the console device
+    input_queue_evt.write(1).unwrap();
+    output_queue_evt.write(1).unwrap();
+    pipe_tx.write_all(console_input_bytes).unwrap(); // To use fuzzed data;
+
+    console
+        .activate(
+            guest_memory,
+            Arc::new(NoopVirtioInterrupt {}),
+            vec![(0, input_queue, input_evt), (1, output_queue, output_evt)],
+        )
+        .unwrap();
+
+    // Wait for the events to finish and console device worker thread to return
+    console.wait_for_epoll_threads();
+});
+
+pub struct NoopVirtioInterrupt {}
+
+impl VirtioInterrupt for NoopVirtioInterrupt {
+    fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> {
+        Ok(())
+    }
+}
+
+fn setup_virt_queues(bytes: &[&[u8; QUEUE_DATA_SIZE]], base_addr: u64) -> Vec<Queue> {
+    let mut queues = Vec::new();
+    for (i, b) in bytes.iter().enumerate() {
+        let mut q = Queue::new(QUEUE_SIZE).unwrap();
+
+        let desc_table_addr = base_addr + (QUEUE_BYTES_SIZE * i) as u64;
+        let avail_ring_addr = desc_table_addr + DESC_TABLE_SIZE;
+        let used_ring_addr = avail_ring_addr + PADDING_SIZE + AVAIL_RING_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_next_avail(b[0] as u16); // 'u8' is enough given the 'QUEUE_SIZE' is small
+        q.set_next_used(b[1] as u16);
+        q.set_event_idx(b[2] % 2 != 0);
+        q.set_size(b[3] as u16 % QUEUE_SIZE);
+
+        q.set_ready(true);
+        queues.push(q);
+    }
+
+    queues
+}
+
+fn memfd_create(name: &std::ffi::CStr) -> Result<RawFd, std::io::Error> {
+    let res = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), 0) };
+
+    if res < 0 {
+        Err(std::io::Error::last_os_error())
+    } else {
+        Ok(res as RawFd)
+    }
+}
+
+fn create_pipe() -> Result<(File, File), std::io::Error> {
+    let mut pipe = [-1; 2];
+    if unsafe { libc::pipe2(pipe.as_mut_ptr(), libc::O_CLOEXEC) } == -1 {
+        return Err(std::io::Error::last_os_error());
+    }
+    let rx = unsafe { File::from_raw_fd(pipe[0]) };
+    let tx = unsafe { File::from_raw_fd(pipe[1]) };
+
+    Ok((rx, tx))
+}