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Crash implies that a software is unstable and possibly vulnerable. Stack overflow is one of many causes of crashes. This kind of bug is often hard to debug because of the corrupted stack, so that debuggers cannot trace the control flow of the programs. A control-type crash caused by stack overflow is easy to be developed as a control interception attack. We develop a method to locate this attack and implement it as a plug-in of Valgrind [1]. This tool can be used in the honeypot to detect and diagnose zero-day exploits. We use it to detect several vulnerabilities and automatically locate the bugs. [ABSTRACT FROM AUTHOR]

Chip multiprocessors (CMPs) with on-chip network connecting processor cores have been pervasively accepted as a promising technology to efficiently utilize the ever increasing density of transistors on a chip. Communications in CMPs require invalidating cached copies of a shared data block. The coherence traffic incurs more and more significant overhead as the number of cores in a CMP increases. Conventional designs of cache coherence protocols do not take into account characteristics of underlying networks for flexibility reasons. However, in CMPs, processor cores and the on-chip network are tightly integrated. Exposing the network features to cache coherence protocols will unveil some optimization opportunities. In this paper, we propose distance aware protocol and multi-target invalidations, which exploit the network characteristics to reduce the invalidation traffic overhead at negligible hardware cost. Experimental results on a 16-core CMP simulator showed that the two mechanisms reduced the average invalidation traffic latency by 5%, up to 8%. [ABSTRACT FROM AUTHOR]

This paper studies the performance of MCs (microcalcifications) recognition in digital mammograms by using a modified autobinomial Markov random field (MRF) model. Fifty 85×85 sample images are selected from the MIAS (Mammographic Image Analysis Society) database for this study. Among these images, 25 samples are of MCs and the other 25 samples are of normal. We model these images by the modified autobinomial model of fourth order, and extract the 12 model parameters as the feature vector of the images by maximum bivariate pseudolikelihood parameter estimation method. The SVM (Support Vector Machine) and BPNN (backpropagation neural network) classifiers are both employed to test the performance of the proposed method. By applying the "leave one out" test approach, an impressive average recognition rate of about 82%, out of the 50 sample data, is achieved. This result demonstrates the potential power of MRF model in the recognition of MCs in digital mammograms. [ABSTRACT FROM AUTHOR]

An antenna array is often used as an adaptive antenna. In this paper, the pattern nulling of a linear array for interference cancellation is derived by phase-only perturbations using genetic algorithms. This design for radiation pattern nulling of an adaptive antenna can suppress multiple interferences by placing nulls at the directions of the interfering sources, i.e., to increase the Signal Interference Ratio (SIR). One example is provided to justify the proposed phase-only perturbations approach based on genetic algorithms. The simulation results show that optimizing interference cancellation of adaptive linear array has been achieved by phase-only perturbations using genetic algorithms. [ABSTRACT FROM AUTHOR]

A novel image protection scheme called "cocktail watermarking" is proposed in this paper. We analyze and point out the inadequacy of the modulation techniques commonly used in ordinary spread spectrum watermarking methods and the visual model-based ones. To resolve this inadequacy, two watermarks which play complementary roles are simultaneously embedded into a host image. The new watermarking scheme has the characterictic that, no matter what an attack is, at least one watermark typically survives well. We also conduct a statistical analysis to derive the lower bound of the worst percentage for the likelihood that the better watermark (of the two) can be extracted. With this "high" lower bound, it is ensured that a "better" extracted watermark is always obtained. Results of extensive experiments indicate that our cocktail watermarking scheme is remarkably effective in resisting various attacks. [ABSTRACT FROM AUTHOR]