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AMD Ryzen Pro CPUs have a memory encryption feature (SME): <https://www.amd.com/system/files/documents/amd-memory-guard-white-paper.pdf https://www.amd.com/syst
by coppsilgold 3y ago
AMD Ryzen Pro CPUs have a memory encryption feature (SME): <https://www.amd.com/system/files/documents/amd-memory-guard-white-paper.pdf https://www.amd.com/system/files/documents/amd-memory-guard-...>
It may require to have support from the motherboard.
EFI firmware has a var (/sys/firmware/efi/efivars/) named MemoryOverwriteRequestControl that if set is supposed to instruct the firmware to overwrite memory on next boot. If you set it and if you can somehow trigger a reboot memory should not be recoverable.
You can also set init_on_free=1 in linux cmdline, the kernel will overwrite freed memory. If a reboot is physically interrupted or if the EFI firmware does not honor the var mentioned above, encryption keys and any other private data may have been freed.
- Unklejoe 3y ago> You can also set init_on_free=1 in linux cmdline, the kernel will overwrite freed memory. Does this only work with kernel buffers? I’m wondering how glibc handles freed memory. I feel like there’s a good chance it doesn’t always notify the kernel that the memory has been freed.
- Cody-99 3y agoNone Pro Ryzen CPUs can use Transparent SME (TSME) if the motherboard includes support for it (and many of them do). Like ECC on non Pro Ryzen chips it isn't 'officially supported' but the option is there and works.