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Indirect function calls are widely used in building system software like OS kernels for their high flexibility and performance. Statically resolving indirect-call targets has been known to be a hard problem, which is a fundamental requirement for various program analysis and protection tasks. The state-of-the-art techniques, which use type analysis, are still imprecise. In this paper, we present a new approach, TFA, that precisely identifies indirect-call targets. The intuition behind TFA is that type-based analysis and data-flow analysis are inherently complementary in resolving indirect-call targets. TFA incorporates a co-analysis system that makes the best use of both type information and data-flow information. The co-analysis keeps refining the global call graph iteratively, allowing us to achieve an optimal indirect call analysis. We have implemented TFA in LLVM and evaluated it against five famous large-scale programs. The experimental results show that TFA eliminates additional 24% to 59% of indirect-call targets compared with the state-of-the-art approaches, without introducing new false negatives. With the precise indirect-call analysis, we further developed a strengthened fine-grained forward-edge control-flow integrity scheme and applied it to the Linux kernel. We have also used the refined indirect-call analysis results in bug detection, where we found 8 deep bugs in the Linux kernel. As a generic technique, the precise indirect-call analysis of TFA can also benefit other applications such as compiler optimization and software debloating. 

Silicon oxycarbide ceramics are an important class of materials that can be modified to cover a wide range of microstructures and compositions during processing. This study focuses on a polysiloxane precursor to SiOC conversion when crosslinked in the presence of 0, 50, 100, and 200 vol% of 3-pentanone, n-heptane, or isobutylbenzene, relative to the volume of the polysiloxane. The solvent modified samples show a decrease in bulk density and an increase in open porosity. The addition of the solvents facilitates the formation of crystalline SiC, especially for 3-pentanone. The ability of the solvents to encourage SiC formation is directly related to the solvent molecular size, with smaller solvents being more likely to increase polymer chain entanglement and remain trapped within the polymer after drying and subsequently creating more C-C and Si-C bonds after pyrolysis. This work shows the unique function of solvents in modifying the SiOC microstructures and properties.