Vulnerabilities emanating from DRAM errors pose a vexing problem that remains, as of yet, unsolved and elusive but cannot be ignored. Prior defenses focused on specific details of early RowHammer attacks and fail to generalize with the generalizations of recent RowHammer attacks. Even worse, it is presently not clear that techniques from prior defenses will be able to cope with these generalizations or if an entirely new approach is required. Although still work-in-progress, we have identified a new approach that combines memory allocation with principles underlying software diversity and shows promising early results. At first glance, software diversity seems to be an unlikely contender, since it faces seemingly insurmountable obstacles, primarily the lack of sufficient entropy in memory subsystems. Our system - called MAD, short for memory allocation diversity - leverages two novel, complementary spatial diversification techniques to overcome this entropy obstacle. Entropy aside, MAD offers ease-of-implementation, negligible performance impact, and is both hardware and software agnostic. From a security perspective, MAD's goal is to deter RowHammer attacks by delaying them to the maximum extent possible. Such a delay opens the door for a variety of additional responses, e.g., proactive rebooting, or complementary in-depth analysis of ongoing attacks that would be too slow for an always-on defense.

翻译：源自DRAM错误的漏洞构成了一个棘手且至今尚未解决、难以捉摸但不可忽视的问题。现有防御机制主要针对早期RowHammer攻击的具体细节，无法适应近期RowHammer攻击的泛化形式。更严峻的是，目前尚不清楚现有防御技术能否应对这些泛化攻击，抑或需要全新的解决方案。尽管仍处于研究阶段，我们发现了一种将内存分配与软件多样性基本原理相结合的新方法，并取得了初步的积极成果。表面看来，软件多样性似乎难以胜任，因其面临看似不可逾越的障碍——主要是内存子系统熵值不足。我们提出的MAD系统（内存分配多样性）通过两种新颖的互补空间多样化技术克服了这一熵值障碍。除熵值问题外，MAD还具有易于实现、性能影响可忽略、软硬件无关等优势。从安全视角看，MAD旨在通过最大限度延缓RowHammer攻击来遏制其威胁。这种延迟为多种附加响应措施创造了条件，例如主动重启系统，或对持续攻击进行深度分析——这类分析对于常驻防御机制而言通常因耗时过长而难以实施。