Earlier quoted context omitted.
Unless the next best thing makes you think you are already achieving the "perfect solution" for what you think you care about, but in truth does not. I'm not a mobile phone security expert but my feeling is that in the case of GrapheneOS - which target is probably high-profile people at risk of state actors et similia attacks - a zero-day in the closed source firmware from Qualcomm will probably screw you anyway. I u…
fyi a Cell Site Simulator can masquerade as the legitimate telco operator and push type 0 messages to the handset. What that means is they can push malicious settings and configurations (Definitely) and probably malicious firmware to the handset at will. They don't need to code this, they buy the software packages from the usual suspects. Adversary simply needs to put a drt box or a hailstorm or what-not close enough…
There's an IOMMU:
> Is the baseband isolated? > Yes, the baseband is isolated on all of the officially supported devices. Memory access is partitioned by the IOMMU and limited to internal memory and memory shared by the driver implementations. [...]
https://grapheneos.org/faq#baseband-isolation
> GrapheneOS cannot really influence this, but hardened_malloc could conceivably help.
They can and do, see above. But I don't see how hardened_malloc is related to the baseband doing DMA.