"Retbleed" Published As Arbitrary Speculative Execution With Return Instructions

[phoronix]

Phoronix: "Retbleed" Published As Arbitrary Speculative Execution With Return Instructions

Being made public this Patch Tuesday is "RETBLEED" as two new CVEs for the latest speculative execution attacks affecting today's hardware. Retbleed exploits return instructions and is able to undermine existing defenses against Spectre Branch Target Injection (BTI)...

https://www.phoronix.com/scan.php?page=news_item&px=RETBLEED

[Vorpal]

Will these patches only enable the slow mitigations on susceptible processors. I.e. Will Zen 3 use the faster mitigation?

Michael I would love it if you tested the effects of the mitigations on both susceptible hardware, and hardware that only needs the previous repoline.

[ms178]

What a massive performance impact! That's killing generations of performance improvements.

[tildearrow]

Downgrade Core i7 to Atom :<

[oibaf]

Will these patches only enable the slow mitigations on susceptible processors. I.e. Will Zen 3 use the faster mitigation?

It doesn't completely reply your question, but from https://comsec.ethz.ch/research/microarch/retbleed/ :

Note that we have only tested AMD CPU family 0x17 (AMD Zen 1, Zen 1+ and Zen 2).

[bezirg]

It looks like Zen3 is unaffected. I hope that the patches should take that into account and not apply the mitigations by default for the case of zen3

[xcom]

Can this affect ps5 with its Zen2 cpu?

[birdie]

It looks like Zen3 is unaffected. I hope that the patches should take that into account and not apply the mitigations by default for the case of zen3

It remains to be seen

Can this affect ps5 with its Zen2 cpu?

Doesn't matter, PS5 and XBox are both very closed systems/architectures and Microsoft and Sony may as well not patch this vulnerability at all.

What a massive performance impact! That's killing generations of performance improvements.

Meltdown v2 only this time AMD Zen1+/Zen2 uArchs are affected.

[Michael]

It looks like Zen3 is unaffected. I hope that the patches should take that into account and not apply the mitigations by default for the case of zen3

https://twitter.com/phoronix/status/1546942317071826945

[MorrisS.]

I've read an article about these vulnerabilities stating that the ratio among intel cpus and amd cpus is circa 100 to 1. Intel Cpus are not bugged are the bug on their own.