Hi Stefan, Stefan Hajnoczi <stefa...@gmail.com> writes:
> Hi folks, > I'd like to start fuzzing emulated devices in QEMU. Here is an > internship project idea I'm proposing to do this. > > Any thoughts? Want to co-mentor this in Google Summer of Code or Outreachy? > > Stefan > > '''Summary:''' Integrate oss-fuzz into QEMU so that the virtio-blk > device can be fuzz tested. > > oss-fuzz offers a fuzz testing service to open source projects. This > means random inputs are continuously tested against the program in > order to find crashes and other bugs. Fuzz testing complements > hand-written test suites by exploring the input space of a program and > therefore the code paths that may be taken. > > The goal of this project is to integrate oss-fuzz into QEMU so that > the virtio-blk-pci device can be fuzzed at both the VIRTIO and PCI bus > level. virtio-blk-pci is a PCI device, which means it is connected to > the virtual machine's PCI bus and has a certain set of registers that > can be programmed by the guest. Furthermore, it is a VIRTIO device - > this is the specification the describes most of the functionality of > virtio-blk. Bugs exist at both the PCI and VIRTIO levels, so it's > important to fuzz both of them. > > Fuzzing emulated devices involves accessing their hardware registers > randomly to make the device respond. QEMU has a device testing > interface called "qtest" that accepts read/write and other commands > over a socket and is ideal for writing device-level tests. You may > find that oss-fuzz works better integrated directly into the QEMU > program instead of as a separate qtest program, so you can consider > adding a new command-line option to QEMU for running in oss-fuzz mode. This sounds very interesting and if successful can easily be a stepping stone to other sections. I would be interested in co-mentoring specifically focusing on the PCI code. One of the things I remember getting into trouble with when I was trying to hack on this, especially fuzzing Qemu as a whole is what would the run environment be like ? Would Qemu attempt to run a regular guest in oss-fuzz mode or only a certain part of Qemu (emulated devices for example) be somehow run without interacting with other dependent components ? Bandan > > This project involves learning about VIRTIO and PCI devices, as well > as figuring out how to integrate oss-fuzz into QEMU so that it can > effective explore the code paths in virtio-blk device emulation code. > You will enjoy this project if you want to learn how device emulation > works and are interested in fuzzers. > > '''Links:''' > * [https://github.com/google/oss-fuzz/blob/master/docs/ideal_integration.md > oss-fuzz integration overview] > * > [https://github.com/google/fuzzer-test-suite/blob/master/tutorial/libFuzzerTutorial.md > libfuzzer tutorial] > * [http://docs.oasis-open.org/virtio/virtio/v1.0/cs04/virtio-v1.0-cs04.html > VIRTIO specification] > * [https://wiki.osdev.org/PCI PCI bus overview] > > '''Details:''' > * Skill level: intermediate > * Language: C > * Mentor: Stefan Hajnoczi <stefa...@redhat.com>
