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Enable ARMv9 Memory Tagging Extension (MTE) on Pixel 8

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Re: Enable ARMv9 Memory Tagging Extension (MTE) on Pixel 8

#5

Multicultural Toronto English? Something else? (site seems dead)

Memory Tagging Extension (MTE)

This allows to assign tag to each memory allocation. And subsequent accesses to the same memory area must be made with a pointer having a correct tag.

Re: Enable ARMv9 Memory Tagging Extension (MTE) on Pixel 8

#7

Multicultural Toronto English? Something else? (site seems dead)

Memory Tagging Extension, an arm v9 hardware feature for mitigating some memory safety bugs.

Is this the outcome of the Morello project? Honestly sounds nice.

Re: Enable ARMv9 Memory Tagging Extension (MTE) on Pixel 8

#9
post #2

Why isn't it enabled by default?

There's probably a very good reason for it.

I would definitely advice anyone against enabling "Developer options" on your phone without having a good understanding what those options do. They are hidden and hard to access for a reason.

Re: Enable ARMv9 Memory Tagging Extension (MTE) on Pixel 8

#10
Consider using GrapheneOS instead of stock Android for an improved version of MTE (and extra security and privacy as a bonus): https://discuss.grapheneos.org/d/8439-mte-support-status-for...

> Stock Pixel OS has it as a developer option which isn't usable in practice since it breaks far too much. The implementation is also much less powerful than hardened_malloc.

> We integrated it into hardened_malloc where it's able to provide stronger security properties than the experimental stock OS implementation.

> When fully integrated into the compiler and each heap allocator, MTE enforces a form of memory safety. It detects memory corruption as it happens. 4 bit tags limit it to probabilistic detection for the general case, but deterministic guarantees are possible via reserving tags. In hardened_malloc, we deterministically prevent sequential overflows by excluding adjacent tags.

Also, currently it's not clear if it makes sense to enable kernel MTE:

> MTE support for protecting the Linux kernel isn't enabled yet, but we can likely enable that by default too. However, it's currently part of kasan and is more oriented towards debugging than hardening. It's not entirely clear that enabling it in the current state is a good idea.

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