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GrapheneOS says Pixel 11 has MTE support after all

grapheneos.social

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Re: GrapheneOS says Pixel 11 has MTE support after all

#62

For anyone else not knowing what MTE stands for: > Memory safety bugs, which are errors in handling memory in native programming languages, are common code issues. They lead to security vulnerabilities as well as stability problems. >Armv9 introduced the Arm Memory Tagging Extension (MTE), a hardware extension that allows you to catch use-after-free and buffer-overflow bugs in your native code. https://developer.andr…

MTE is essentially hardware-accelerated AddressSanitiser[1]. [1]: https://clang.llvm.org/docs/AddressSanitizer.html

No MTE and AddressSanitizer are implemented completely differently under the hood and catch different kinds of memory bugs.

MTE tracks provenance of pointers which means it catches bugs where a valid pointer derived from one allocation is used to access another allocation. Provenance is indicated by a fixed number of tags available. So there’s a 7% chance of not detecting an occurrence of a memory bug.

ASan is implemented differently: it adds red zones next to allocations. In theory it could have a false negative if a pointer jumps over the poisoned region. But it works well for stack memory in addition to heap memory. MTE doesn’t protect your stack allocated objects.

Re: GrapheneOS says Pixel 11 has MTE support after all

#63

So not only a price increase: less RAM, performance scraping backwards, crippled/lost features, a camera system that captures stuttering audio and video imperfectly often, and Pixels dropping out of AOSP. Google Pixel has the marketshare it deserves.

There's no phone that isn't like that this year

Fairphone gen6+ (vs gen6) got an increase in ram from 8 to 12 and from Snapdragon 7s gen3 to gen4. MSRP only went from 599 to 649.

Re: GrapheneOS says Pixel 11 has MTE support after all

#65

Earlier quoted context omitted.

MTE is essentially hardware-accelerated AddressSanitiser[1]. [1]: https://clang.llvm.org/docs/AddressSanitizer.html

To expand a bit: 16-byte chunks of memory can be associated with a four bit tag. Then you steal four unused high bits from your pointers to store a tag value. When memory has a tag, a pointer used to access it must have the matching tag in its high bits. Your malloc implementation can then assign a different tag to adjacent allocations and any overflow into an adjacent allocation will have a mismatched tag and will t…

4 bits per 16 bytes is ~ 1/4 the cost of ECC, which is possible to implement with just an extra cycle or two of latency in the memory controller. MTE seems similarly lightweight. Costs some transistors and a percent of a percent of power budget, but much like ECC it seems a fair bargain.

Re: GrapheneOS says Pixel 11 has MTE support after all

#66

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Thankfully the project doesn't care about your personal attitude. That "niche use case" literally saves lives in countries where saying the wrong thing can put you to death. Since when is calling something out a rant?

[flagged]

Re: GrapheneOS says Pixel 11 has MTE support after all

#67

Unfortunately, the headline is somewhat optimistic compared to the reality, I think. The thread makes it sound like it could have been disabled due to errata or performance issues. Basically, it looks like the software Google is shipping intentionally doesn't use MTE on the Pixel 11 hardware. That raises the question of...what does Google know is wrong with MTE on the Pixel 11?

Nothing is wrong. They just don't use MTE yet, they probably have other priorities. They wanted to save some costs until they will use MTE, so they removed some hardware acceleration and downgraded the GPU. Simple as that.

AFAIK the other Pixel devices, going back to the 8, do use MTE in the stock OS. Some MTE features are only enabled when "Advanced Protection" is turned on in the OS settings, but the stock OS on those devices does make use of MTE. In the Android documentation, MTE is explicitly called out as one of the protection features enabled in the Advanced Protection mode.

So, I don't think it's accurate to say they don't use it yet. They were using it, and then they stopped. I think that's one of the reasons the linked GOS thread says they're concerned that "MTE may actually be broken due to CPU errata".

Re: GrapheneOS says Pixel 11 has MTE support after all

#68

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> As much as it seems beloved here, people that flash custom Android OSs are the very definition of niche users.

Hmm... Let's try reframing this: "as much as it seems beloved here, people that install their own operating systems on PCs are the very definition of niche users"

I'm absolutely certain that's how IBM felt before the clones. But the ability to install what they wanted on a defacto standard platform is what launched the computing revolution. I think we'd still be living in a sterile monopolistic environment with $10k compilers otherwise.

Folks installing their own ROMs on phones are only niche because they've been pushed out at every opportunity using locked bootloaders, embedded security processors, factory installed secret keys, etc.

Despite all that, there's still thriving communities developing and using custom ROMs on their phones. That demonstrates more than niche demand.

Re: GrapheneOS says Pixel 11 has MTE support after all

#69
post #12
post #9

So, where does the restriction for side loading apps live, on the device or the OS? Curious about getting the Pixel 11 Pro if/when I can install GrapheneOS.

GrapheneOS themselves said it wasn't worth getting the 11 over the 10 on Twitter. It has a worse GPU and less RAM, and the increase in CPU speed is so negligible that often you end up with better performance using the previous generation. In addition, GrapheneOS isn't even available on 11 series devices yet.

The 11 series has a new MediaTek modem compared to previous Pixels(since 7 I think?). The old modem had power efficiency issues during poor cellular signal as well as a relatively lengthy GPS lock acquisition.

I don't think there is enough evidence yet about either but I can attest that GPS feels improved over my 7. It's only been 1 week though.

The non-Pro 11 has a much larger photo sensor and has more base storage. Everyone has different priorities. I'm not saying which is better but trying to give a more complete picture.

Re: GrapheneOS says Pixel 11 has MTE support after all

#70

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If they're just some "niche use case" then why would Motorola partner with them? The way they see it,

> By combining GrapheneOS’s pioneering engineering with Motorola’s decades of security expertise, real‑world user insights, and Lenovo’s ThinkShield solutions, the collaboration will advance a new generation of privacy and security technologies. In the coming months, Motorola and the GrapheneOS Foundation will continue to collaborate on joint research, software enhancements, and new security capabilities, with more details and solutions to roll out as the partnership evolves.

https://motorolanews.com/motorola-three-new-b2b-solutions-at...

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