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Environment

The setup is tested on Ubuntu 18.04.5 LTS.

prerequisites

Please uncomment deb-src lines in /etc/apt/sources.list in your system, then run the following commands:

sudo apt-get update
sudo apt-get build-dep qemu

Then please run build.sh to build the fuzzer and qemu.

Fuzzing linux kernel

Preparing the kernel

  1. download a version of Linxu kernel and apply the patches in OSes/linux-target/kernel-patches (the patches are based on v5.5, if you use other versions, the patches may not apply directly and need to be modified).
  2. start building the kernel using the kernel config file in OSes/linux-target/kconfig

Preparing a Linux userspace image

If you do not want to build the image by yourself, you can download an image directly from here.

Otherwise, run the script in scripts directory using the following command:

scripts/create-image.sh -f full

After the system image is built, please run the image using the following image

usbfuzz-afl/qemu_mode/qemu-build/x86_64-softmmu/qemu-system-x86_64 -M q35 -net nic,model=e1000 -net user,host=10.0.2.10,hostfwd=tcp::1569-:22 -m 4G -enable-kvm -object memory-backend-shm,id=shm -device ivshmem-plain,id=ivshmem,memdev=shm -kernel <path_to_bzImage> -append "root=/dev/sda console=ttyS0" -hda <path_to_linux_image_file>

After the guest system is up, copy OSes/linux-target/user-mode-agent to the guest system and run install.sh in the guest system.

running the fuzzer

Please use the python frontend named USBFuzz to start the fuzzer (for how to use the script, please run USBFuzz --help). Before starting the fuzzer, you may need to run the scripts/kernel_config.sh.

E.g.:

/USBFuzz --seeddir seeds --kernel_image OSes/linux-target/linux-test-build/arch/x86_64/boot/bzImage --os_image images/linux/stretch.img

reproducing a bug

Given that you have found a USB bug, you may need to reproduce the bug. Assume that we have found a bug and the crashing input is saved in bugs/bug1.

  1. run the following command to start the guest vm:
./usbfuzz-afl/qemu_mode/qemu-build/x86_64-softmmu/qemu-system-x86_64 -M q35 -device qemu-xhci,id=xhci  -object memory-backend-shm,id=shm -device ivshmem-plain,id=ivshmem,memdev=shm  -m 4G -enable-kvm -kernel OSes/linux-target/linux-test-build/arch/x86_64/boot/bzImage  -hda images/linux/stretch.img -append 'root=/dev/sda console=ttyS0' -usbDescFile seeds/usb_sk4Wm9j -serial stdio
  1. After the VM is startup, in the View menu, click Show Tabs, then in the compat_monitor0 tab, input the following command,
device_add usb-fuzz,id=fuzz1

Then you will get a bug report on the terminal.

Fuzzing FreeBSD

To fuzz FreeBSD system, you can download a FreeBSD system image from here To start fuzzing, run the following command:

./USBFuzz  --aflfuzz_opts "-n" --seeddir seeds --os_image <path_to_freebsd_image>