4,446 research outputs found

    A software approach to defeating side channels in last-level caches

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    We present a software approach to mitigate access-driven side-channel attacks that leverage last-level caches (LLCs) shared across cores to leak information between security domains (e.g., tenants in a cloud). Our approach dynamically manages physical memory pages shared between security domains to disable sharing of LLC lines, thus preventing "Flush-Reload" side channels via LLCs. It also manages cacheability of memory pages to thwart cross-tenant "Prime-Probe" attacks in LLCs. We have implemented our approach as a memory management subsystem called CacheBar within the Linux kernel to intervene on such side channels across container boundaries, as containers are a common method for enforcing tenant isolation in Platform-as-a-Service (PaaS) clouds. Through formal verification, principled analysis, and empirical evaluation, we show that CacheBar achieves strong security with small performance overheads for PaaS workloads

    A search for rotating radio transients and fast radio bursts in the Parkes high-latitude pulsar survey

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    Discoveries of rotating radio transients and fast radio bursts (FRBs) in pulsar surveys suggest that more of such transient sources await discovery in archival data sets. Here we report on a single-pulse search for dispersed radio bursts over a wide range of Galactic latitudes (|b| < 6060^{\circ}) in data previously searched for periodic sources by Burgay et al. We re-detected 20 of the 42 pulsars reported by Burgay et al. and one rotating radio transient reported by Burke-Spolaor. No FRBs were discovered in this survey. Taking into account this result, and other recent surveys at Parkes, we corrected for detection sensitivities based on the search software used in the analyses and the different backends used in these surveys and find that the all-sky FRB event rate for sources with a fluence above 4.0 Jy ms at 1.4 GHz to be R=4.43.1+5.2×103{\cal R} = 4.4^{+5.2}_{-3.1} \times 10^3 FRBs day1^{-1} sky1^{-1}, where the uncertainties represent a 99%99\% confidence interval. While this rate is lower than inferred from previous studies, as we demonstrate, this combined event rate is consistent with the results of all systematic FRB searches at Parkes to date and does not require the need to postulate a dearth of FRBs at intermediate latitudes.Comment: Accepted, 10 pages, 6 figure

    A short note on a mutation of Cheema-sahebi (Syn. Selection-7)

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    Kurze Mitteilung iiber eine Mutante von Cheema-sahebi (Syn. Selection-7)Die Trauben- und Beerenmerkmale einer spontan entstandenen Knospenmutante der Tafeltraubensorte Cheema-sahebi werden beschrieben. Die Beeren der Mutante sind gegenüber der Ausgangsform auffällig verlängert. Während diese bei Verpackung und Transport 8-100/o ihrer Beeren verliert, zeichnet sich die Mutante durch eine hohe Haftfestigkeit ihrer Beeren aus