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David Crawshaw
@crawshaw.io

I am curious to see what memory bugs remain practical on iOS with MIE and typed allocators. The fact that memory tags are enforced even in kernel access to userspace memory is going to make use-after-free and buffer overflows extremely hard. security.apple.com/blog/memory-...

security.apple.comBlog - Memory Integrity Enforcement: A complete vision for memory safety in Apple devices - Apple Security ResearchMemory Integrity Enforcement (MIE) is the culmination of an unprecedented design and engineering effort spanning half a decade that combines the unique strengths of Apple silicon hardware with our adv...
David Crawshaw
@crawshaw.io

This comes to macOS next year. The security argument for Chrome over Safari disappears? The hardware reaches Graviton three years later, but retooling the linux kernel and userland around typed allocators takes at least 5-8 years? Until then all computing worth doing has to be on a Mac?

David Crawshaw
@crawshaw.io

C++ is good enough again? Will any arguments for productivity-costing modern language techniques like borrow checking survive if memory tagging actually works? Will security teams ban sensitive work happening on x86 laptops and desktops for 5+ years? Lots of change ahead!

strđź‘»d
@str4d.xyz

You will likely still want borrow-checking and its ilk, but for the new purpose of ensuring that your code runs reliably (or at all) on the new hardware. MTE violations mean crashes, which likely is still a DoS vector for software that handles untrusted inputs.

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David Crawshaw
@crawshaw.io

Much more dramatically: I would shift some software from garbage collected languages to C++ (or some equivalent) if the safety concerns evaporated, because it becomes a pure productivity/performance tradeoff. Exciting times!