Brief Industry Paper: Directed Kernel Fuzz Testing on Real-time Linux.

Rt-Linux contains critical modifications that are much less tested than the vanilla kernel, thus placing many systems at risk. In this paper, we present DRLF, a directed fuzzer targeted towards fuzzing any code area in Rt- Linux, thus allowing for more efficient tests on Rt-Linux's unique code sections. DRLF performs directed fuzzing through a kernel-level weighted callgraph construction technique, and prioritizing input sequences that exhibit less distance to the target code. Evaluations show that DRLF delivers better cover speed while achieving a 24.70% coverage increase for the targeting code areas. DRLF also found 11 previously unknown bugs within Rt-Linux, and has been integrated into Alibaba's CI/CD pipeline.