Build a Fake Phone, Find Real Bugs: Qualcomm GPU Emulation and Fuzzing with LibAFL QEMU

Mobile phones are central to everyday life: we communicate, entertain ourselves, and keep vast swaths of our digital lives on them. That ubiquity makes high-risk groups such as journalists, activists, and dissidents prime targets for sophisticated spyware that exploits device vulnerabilities. On Android devices, GPU drivers have repeatedly served as the final escalation vector into the kernel. To study and mitigate that risk, we undertook a research project to virtualize the Qualcomm Android kernel and the KGSL graphics driver from scratch in QEMU. This new environment enables deep debugging, efficient coverage collection, and large-scale fuzzing across server farms, instead of relying on a handful of preproduction devices. This talk will highlight the technical aspects of our research, starting with the steps required to boot the Qualcomm mobile kernel in QEMU, all the way up to the partial emulation of the GPU. Then, we will present how we moved from our emulation prototype to a full-fledged fuzzer based on LibAFL QEMU.