fuzz: Add fuzzer for virtio-mem

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

fuzz/Cargo.toml

@@ -63,6 +63,12 @@ path = "fuzz_targets/http_api.rs"
 test = false
 doc = false
 
+[[bin]]
+name = "mem"
+path = "fuzz_targets/mem.rs"
+test = false
+doc = false
+
 [[bin]]
 name = "pmem"
 path = "fuzz_targets/pmem.rs"

fuzz/fuzz_targets/mem.rs

@@ -0,0 +1,178 @@
+// Copyright © 2022 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+use seccompiler::SeccompAction;
+use std::os::unix::io::{AsRawFd, FromRawFd};
+use std::sync::{Arc, Mutex};
+use virtio_devices::{BlocksState, Mem, 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>;
+type GuestRegionMmap = vm_memory::GuestRegionMmap<AtomicBitmap>;
+
+macro_rules! align {
+    ($n:expr, $align:expr) => {{
+        (($n + $align - 1) / $align) * $align
+    }};
+}
+
+const VIRTIO_MEM_DATA_SIZE: usize = 2;
+const QUEUE_DATA_SIZE: usize = 4;
+// The size of the guest memory for the virtio-mem region
+const MEM_SIZE: usize = 128 * 1024 * 1024;
+// The start address of the virtio-mem region in the guest memory
+const VIRTIO_MEM_REGION_ADDRESS: u64 = 0;
+
+// Max entries in the queue.
+const QUEUE_SIZE: u16 = 64;
+// Descriptor table alignment
+const DESC_TABLE_ALIGN_SIZE: u64 = 16;
+// Avalable ring alignment
+const AVAIL_RING_ALIGN_SIZE: u64 = 2;
+// 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;
+// Used ring size
+const USED_RING_SIZE: u64 = 6_u64 + 8 * QUEUE_SIZE as u64;
+
+// Guest memory gap
+const GUEST_MEM_GAP: u64 = 1 * 1024 * 1024;
+// Guest physical address for descriptor table.
+const DESC_TABLE_ADDR: u64 = align!(MEM_SIZE as u64 + GUEST_MEM_GAP, DESC_TABLE_ALIGN_SIZE);
+// Guest physical address for available ring
+const AVAIL_RING_ADDR: u64 = align!(DESC_TABLE_ADDR + DESC_TABLE_SIZE, AVAIL_RING_ALIGN_SIZE);
+// Guest physical address for used ring
+const USED_RING_ADDR: u64 = align!(AVAIL_RING_ADDR + AVAIL_RING_SIZE, USED_RING_ALIGN_SIZE);
+// Virtio-queue size in bytes
+const QUEUE_BYTES_SIZE: usize = (USED_RING_ADDR + USED_RING_SIZE - DESC_TABLE_ADDR) as usize;
+
+fuzz_target!(|bytes| {
+    if bytes.len() < VIRTIO_MEM_DATA_SIZE + QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE
+        || bytes.len() > (VIRTIO_MEM_DATA_SIZE + QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE + MEM_SIZE)
+    {
+        return;
+    }
+
+    let virtio_mem_data = &bytes[..VIRTIO_MEM_DATA_SIZE];
+    let queue_data = &bytes[VIRTIO_MEM_DATA_SIZE..VIRTIO_MEM_DATA_SIZE + QUEUE_DATA_SIZE];
+    let queue_bytes = &bytes[VIRTIO_MEM_DATA_SIZE + QUEUE_DATA_SIZE
+        ..VIRTIO_MEM_DATA_SIZE + QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE];
+    let mem_bytes = &bytes[VIRTIO_MEM_DATA_SIZE + QUEUE_DATA_SIZE + QUEUE_BYTES_SIZE..];
+
+    // Create a virtio-mem device based on the input bytes;
+    let (mut virtio_mem, virtio_mem_region) =
+        create_dummy_virtio_mem(virtio_mem_data.try_into().unwrap());
+
+    // 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(DESC_TABLE_ADDR), QUEUE_BYTES_SIZE), // guest region for the virt queue
+    ])
+    .unwrap();
+    if mem
+        .write_slice(queue_bytes, GuestAddress(DESC_TABLE_ADDR))
+        .is_err()
+    {
+        return;
+    }
+    // Add the memory region for the virtio-mem device
+    let mem = mem.insert_region(virtio_mem_region).unwrap();
+    if mem
+        .write_slice(mem_bytes, GuestAddress(VIRTIO_MEM_REGION_ADDRESS))
+        .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 virtio-mem device
+    queue_evt.write(1).unwrap();
+
+    virtio_mem
+        .activate(
+            guest_memory,
+            Arc::new(NoopVirtioInterrupt {}),
+            vec![(0, q, evt)],
+        )
+        .ok();
+
+    // Wait for the events to finish and virtio-mem device worker thread to return
+    virtio_mem.wait_for_epoll_threads();
+});
+
+pub struct NoopVirtioInterrupt {}
+
+impl VirtioInterrupt for NoopVirtioInterrupt {
+    fn trigger(&self, _int_type: VirtioInterruptType) -> std::result::Result<(), std::io::Error> {
+        Ok(())
+    }
+}
+
+// Create a dummy virtio-mem device for fuzzing purpose only
+fn create_dummy_virtio_mem(bytes: &[u8; VIRTIO_MEM_DATA_SIZE]) -> (Mem, Arc<GuestRegionMmap>) {
+    let hugepages = bytes[0] % 2 != 0;
+    let numa_id = if bytes[1] % 2 != 0 { Some(0) } else { None };
+
+    let region = vmm::memory_manager::MemoryManager::create_ram_region(
+        &None,
+        0,
+        GuestAddress(VIRTIO_MEM_REGION_ADDRESS),
+        MEM_SIZE,
+        false,
+        false,
+        hugepages,
+        None,
+        numa_id,
+        None,
+    )
+    .unwrap();
+
+    let blocks_state = Arc::new(Mutex::new(BlocksState::new(region.size() as u64)));
+
+    (
+        Mem::new(
+            "fuzzer_mem".to_owned(),
+            &region,
+            SeccompAction::Allow,
+            numa_id.map(|i| i as u16),
+            0,
+            hugepages,
+            EventFd::new(EFD_NONBLOCK).unwrap(),
+            blocks_state.clone(),
+        )
+        .unwrap(),
+        region,
+    )
+}
+
+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
+}