Figure 1: How branch misprediction leads to speculative execution. When the branch predictor makes an incorrect guess about the destination of a conditional branch, some instructions are speculatively executed. The execution of these instructions is undone, but their effects on the cache remain. Spectre causes the branch predictor to guess wrong and speculatively execute a carefully chosen set of instructions.

An accessible overview of Meltdown and Spectre, Part 2

This is the second half of our blog post on the Meltdown an Spectre vulnerabilities, describing Spectre Variant 1 (V1) and Spectre Variant 2 (V2). If you have not done so already, please review the first blog post for an accessible review of computer architecture fundamentals. This blog post will ... Read More
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An accessible overview of Meltdown and Spectre, Part 1

In the past few weeks the details of two critical design flaws in modern processors were finally revealed to the public. Much has been written about the impact of Meltdown and Spectre, but there is scant detail about what these attacks are and how they work. We are going to ... Read More
Valid destinations for indirect calls in ClangCFI and CFGuard

The Challenges of Deploying Security Mitigations

| | Compilers, Mitigations
This blog has promoted control flow integrity (CFI) as a game changing security mitigation and encouraged its use. We wanted to take our own security advice and start securing software we use. To that end, we decided to apply CFI to facebook’s osquery, a cross-platform codebase with which we are ... Read More