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An Experimental Characterization of Combined RowHammer and RowPress Read Disturbance in Modern DRAM Chips

Haocong Luo, Ismail Emir Yüksel, Ataberk Olgun, A. Giray Yağlıkçı, Mohammad Sadrosadati, Onur Mutlu

TL;DR

This study characterize a DRAM access pattern that combines RowHammer and RowPress in 84 real DDR4 DRAM chips from all three major DRAM manufacturers and provides a key hypothesis that the read disturbance effect caused by RowPress from one of the two aggressor rows in a double-sided pattern is much more significant than the other.

Abstract

DRAM read disturbance can break memory isolation, a fundamental property to ensure system robustness (i.e., reliability, security, safety). RowHammer and RowPress are two different DRAM read disturbance phenomena. RowHammer induces bitflips in physically adjacent victim DRAM rows by repeatedly opening and closing an aggressor DRAM row, while RowPress induces bitflips by keeping an aggressor DRAM row open for a long period of time. In this study, we characterize a DRAM access pattern that combines RowHammer and RowPress in 84 real DDR4 DRAM chips from all three major DRAM manufacturers. Our key results show that 1) this combined RowHammer and RowPress pattern takes significantly smaller amount of time (up to 46.1% faster) to induce the first bitflip compared to the state-of-the-art RowPress pattern, and 2) at the minimum aggressor row activation count to induce at least one bitflip, the bits that flip are different across RowHammer, RowPress, and the combined patterns. Based on our results, we provide a key hypothesis that the read disturbance effect caused by RowPress from one of the two aggressor rows in a double-sided pattern is much more significant than the other.

An Experimental Characterization of Combined RowHammer and RowPress Read Disturbance in Modern DRAM Chips

TL;DR

This study characterize a DRAM access pattern that combines RowHammer and RowPress in 84 real DDR4 DRAM chips from all three major DRAM manufacturers and provides a key hypothesis that the read disturbance effect caused by RowPress from one of the two aggressor rows in a double-sided pattern is much more significant than the other.

Abstract

DRAM read disturbance can break memory isolation, a fundamental property to ensure system robustness (i.e., reliability, security, safety). RowHammer and RowPress are two different DRAM read disturbance phenomena. RowHammer induces bitflips in physically adjacent victim DRAM rows by repeatedly opening and closing an aggressor DRAM row, while RowPress induces bitflips by keeping an aggressor DRAM row open for a long period of time. In this study, we characterize a DRAM access pattern that combines RowHammer and RowPress in 84 real DDR4 DRAM chips from all three major DRAM manufacturers. Our key results show that 1) this combined RowHammer and RowPress pattern takes significantly smaller amount of time (up to 46.1% faster) to induce the first bitflip compared to the state-of-the-art RowPress pattern, and 2) at the minimum aggressor row activation count to induce at least one bitflip, the bits that flip are different across RowHammer, RowPress, and the combined patterns. Based on our results, we provide a key hypothesis that the read disturbance effect caused by RowPress from one of the two aggressor rows in a double-sided pattern is much more significant than the other.
Paper Structure (14 sections, 6 figures, 2 tables)

This paper contains 14 sections, 6 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Background
  3. DRAM Organization
  4. Key DRAM Operation and Timing
  5. DRAM Read Disturbance
  6. Experimental Methodology
  7. DRAM Characterization Infrastructure
  8. Commodity DDR4 DRAM Chips Tested
  9. Combined RowHammer and RowPress Pattern
  10. Real DRAM Chip Characterization Methodology
  11. Major Characterization Results
  12. Related Works
  13. Conclusion
  14. Appendix

Figures (6)

  • Figure 1: The combined RowHammer and RowPress pattern.
  • Figure 2: Hierarchical organization of modern DRAM. Reproduced from yaglikci2022understandingluo2023rowpress.
  • Figure 3: Comparison of a) the conventional single-sided RowPress (RowHammer, when tAggON = tRAS) pattern, b) the conventional double-sided RowPress (RowHammer, when tAggON = tRAS) pattern, and c) the combined RowHammer and RowPress pattern.
  • Figure 4: Time to first bitflip (first row of plots) and (second row of plots) of the combined RowHammer and RowPress pattern (blue solid line) and the conventional single- and double-sided RowPress (RowHammer) patterns (green and orange dashed lines).
  • Figure 5: The fraction of 1 to 0 bitflips due to the combined RowHammer and RowPress pattern.
  • ...and 1 more figures