EntrySign is a vulnerability that enables attackers with ring 0 or kernel-level access to bypass safeguards.
So almost no security impact and no performance change?
this post was submitted on 11 Apr 2025
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no performance change
You must be new here.
Joking. In reality it depends.
The first iteration of this comment had a cheeky observation about the performance impact of these CPU mitigations on Linux, some of which have nearly no real world threat to people not running cloud providers.
And while that's true to a degree, tests disabling some or all of the most modern set of mitigations show that most have become highly optimized and the CPUs themselves have iterated over time to increase the performance of the mitigations as well.
And many of these CPU vulnerabilities actually had in the wild use and can still do horrible things with very little surface exposure from your system. Apologies to the people who read the first version of this comment and took the time to rightly push back.
weakness in signature verification algorithm that could allow an administrator privileged attacker to load arbitrary microcode patches
I don't think this will affect performance unless you depend on having to quickly update the CPU microcode multiple times a second.
I apologize for being glib.
Agreed, shouldn't affect performance. But also depends on how they see best to patch the vulnerability. The microcode patch mechanism is the currently understood vector, but might not be the only way to exploit the actual underlying vulnerability.
I remember the early days of Spectre when the mitigation was "disable branch prediction", then later they patched a more targeted, performant solution in.
Running untrusted Javascript code from the internet without security mitigations is a bad idea. It's maybe excusable for servers but it still increases the risk of container break out if one of the 100 containers you're running is attacked.
Yeah... I mean, I did hedge by saying "depends on your CPU and your risk profile", but I understand your point and will edit my comment to caution readers before playing with foot finding firearms.
From my understanding it's a mixed bag. Some of those vulnerabilities were little more than theoretical exploits from within high levels of trust, like this one. Important if you're doing a PaaS/IaaS workload like AWS, GCP etc and you need to keep unknown workloads safe, and your hypervisor safe from unknown workloads.
Others were super scary direct access to in-memory processes type vulnerabilities. On Linux you can disable certain mitigations while not disabling others, so in theory you could find your way to better performance at a near zero threat increase, but yes, better safe than sorry.
How do I update through linux?
You update through UEFI
Maybe fwupd?
Sounds terrible, but fortunately an update is available