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Now the new Raspberry 4 has moved to ARM A72 cores, it's vulnerable to the spectre issues according to ARM.

Processor   Variant 1 Variant 2 Variant 3 Variant 3a Variant 4
Cortex-A72   Yes        Yes**    No**      Yes**    Yes

But this gives no output:

ls -1A /sys/devices/system/cpu/vulnerabilities
cat /sys/devices/system/cpu/vulnerabilities/*

'/sys/devices/system/cpu/vulnerabilities/*': No such file or directory

I do wonder if hardware or software mitigations are in place?

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The Raspberry Pi 4 is using ARM A72, and those ARM A72 Cores have Speculative Processor Vulnerabilities.

ARM recommends mitigation mechanisms.

The Raspberry Pi 4 has those mitigations enabled in the Raspbian Kernel.

How to check:

sudo modprobe configs
zcat /proc/config.gz | grep SPECTRE

CONFIG_CPU_SPECTRE=y

Therefor it is safe to say that an updated Raspberry Pi 4 is not vulnerable for (any known) Spectre Exploits.

But it is still vulnerable for Spectre issues. Mitigations are mitigations, not fixes.

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  • this is incorrect. a fully updated Raspberry Pi 4 is still vulnerable to Variant 3a (rogue system register read) and Variant 4 (speculative store bypass). it is unlikely that the system registers that can be read with Variant 3a would contain any sensitive information, but Variant 4 is a much more serious issue. firmware updates are necessary to mitigate both variants (3a and 4), and those aren't available for the Raspberry Pi 4 yet.
    – lily wilson
    Commented Jul 24, 2020 at 2:35
  • Are there any known exploits?
    – Janghou
    Commented Jul 29, 2020 at 19:08
  • github.com/google/safeside/blob/main/demos/spectre_v4.cc
    – lily wilson
    Commented Aug 10, 2020 at 10:11

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