ZebRAM: comprehensive and compatible software protection against rowhammer attacks
Radhesh Krishnan Konoth, Marco Oliverio, Andrei Tatar, Dennis Andriesse, Herbert Bos, Cristiano Giuffrida, Kaveh Razavi · VU Research Portal · 2018
The Rowhammer vulnerability common to many modern DRAM chips allows attackers to trigger bit flips in a row of memory cells by accessing the adjacent rows at high frequencies. As a result, they are able to corrupt sensitive data structures (such as page tables, cryptographic keys, object pointers, or even instructions in a program), and circumvent all existing defenses. This paper introduces ZebRAM, a novel and compre- hensive software-level protection against Rowhammer. ZebRAM isolates every DRAM row that contains data with guard rows that absorb any Rowhammer-induced bit flips; the only known method to protect against all forms of Rowhammer. Rather than leaving guard rows unused, ZebRAM improves performance by using the guard rows as efficient, integrity-checked and optionally compressed swap space. ZebRAM requires no hardware modifications and builds on virtualization extensions in commodity pro- cessors to transparently control data placement in DRAM. Our evaluation shows that ZebRAM provides strong se- curity guarantees while utilizing all available memory.