We provide an overview of recent developments and future directions in the RowHammer vulnerability that plagues modern DRAM (Dynamic Random Memory Access) chips, which are used in almost all computing systems as main memory. RowHammer is the phenomenon in which repeatedly accessing a row in a real DRAM chip causes bitflips (i.e., data corruption) in physically nearby rows. This phenomenon leads to a serious and widespread system security vulnerability, as many works since the original RowHammer paper in 2014 have shown. Recent analysis of the RowHammer phenomenon reveals that the problem is getting much worse as DRAM technology scaling continues: newer DRAM chips are fundamentally more vulnerable to RowHammer at the device and circuit levels. Deeper analysis of RowHammer shows that there are many dimensions to the problem as the vulnerability is sensitive to many variables, including environmental conditions (temperature \& voltage), process variation, stored data patterns, as well as memory access patterns and memory control policies. As such, it has proven difficult to devise fully-secure and very efficient (i.e., low-overhead in performance, energy, area) protection mechanisms against RowHammer and attempts made by DRAM manufacturers have been shown to lack security guarantees. After reviewing various recent developments in exploiting, understanding, and mitigating RowHammer, we discuss future directions that we believe are critical for solving the RowHammer problem. We argue for two major directions to amplify research and development efforts in: 1) building a much deeper understanding of the problem and its many dimensions, in both cutting-edge DRAM chips and computing systems deployed in the field, and 2) the design and development of extremely efficient and fully-secure solutions via system-memory cooperation.

翻译：本文概述了困扰现代DRAM（动态随机存取存储器）芯片的RowHammer漏洞的最新进展和未来方向。DRAM芯片在几乎所有计算系统中被用作主内存。RowHammer现象是指对实际DRAM芯片中某一行进行重复访问，会导致物理相邻行发生比特翻转（即数据损坏）。自2014年原始RowHammer论文发表以来，大量研究表明，该现象引发了严重且普遍的系统安全漏洞。对RowHammer现象的最新分析揭示，随着DRAM技术不断微缩，问题正变得更加严峻：在器件和电路层面，新一代DRAM芯片根本上更易受到RowHammer攻击。对RowHammer的深入分析表明，该问题具有多个维度，因为漏洞对多种变量敏感，包括环境条件（温度和电压）、工艺偏差、存储数据模式，以及内存访问模式和内存控制策略。因此，设计完全安全且非常高效（即在性能、能耗、面积方面开销低）的RowHammer防护机制已被证明是困难的，而DRAM制造商尝试的措施也被表明缺乏安全保障。在回顾了利用、理解和缓解RowHammer的各种最新进展后，我们讨论了我们认为对解决RowHammer问题至关重要的未来方向。我们主张两个主要方向，以加强研究和发展努力：1) 在尖端DRAM芯片和现场部署的计算系统中，对问题及其多个维度建立更深入的理解；2) 通过系统-内存协作，设计和开发极其高效且完全安全的解决方案。