Survey of Protections from Buffer-Overflow Attacks

Buffer-overflow attacks began two decades ago and persist today. Over that time, many solutions to provide protection from buffer-overflow attacks have been proposed by a number of researchers. They all aim to either prevent or protect against buffer-overflow attacks. As defenses improved, attacks adapted and became more sophisticated. Given the maturity of field and the fact that some solutions now exist that can prevent most buffer-overflow attacks, we believe it is time to survey these schemes and examine their critical issues. As part of this survey, we have grouped approaches into three board categories to provide a basis for understanding buffer-overflow protection schemes

Predicting the Performance of a Wormhole Routed Network with Non-uniform Communication

Contention has been shown to degrade communication in the recently introduced wormhole-routed computers. In this paper, we develop a theoretical framework to model and predict the effect of contention on the communication performance for a given application with non-uniform communication. A two-parameter metric is introduced as a measure of quality of a mapping of an application to a multicomputer. We show that performance can be reasonably predicted if we know path contention levels and the new max load traffic, l max , introduced here. Careful mappings that reduce path contention levels and l max are shown to improve performance. Our theoretical results are validated by simulation results. We conclude that minimizing the two parameters developed in the model can be a reasonable mapping objective. Keywords: Multicomputers, Wormhole routing, Communication performance, Mapping, Contention 1 Introduction The two main components of parallel processing are the computation and the commu..

COMPUTING APPLICATIONS USING AMDAHL AS A METRIC USING AMDAHL’S LAW AS A METRIC TO DRIVE CODE PARALLELIZATION: TWO CASE STUDIES

Using Amdahl’s law as a metric, the authors illustrate a technique for developing efficient code on massively parallel processor (MPP) performance class networks to solve nontrivial, high performance scientific problems. They also show the importance of collective communication within the message-passing interface (MPI) paradigm for some applications. Given the popularity of Beowulf-like clusters of workstations, this work also indicates the necessity of a scalable high performance network for obtaining efficient performance in parallel code. Using this approach, the authors were able to obtain an effective speedup (comparison with the best sequential time) of 170 when using 256 of the Cray T3E 900 processing elements (PEs) to solve a carbon, molecular-dynamic problem. The authors also examine the approach on a very different application: a Lanczos eigenvalue solver