Restbleed

[igor_kavinski]

Retbleed: Arbitrary Speculative Code Execution with Return Instructions – Computer Security Group (ethz.ch)

Mitigating Retbleed in the Linux kernel required a substantial effort, involving changes to 68 files, 1783 new lines and 387 removed lines. Our performance evaluation shows that mitigating Retbleed has unfortunately turned out to be expensive: we have measured between 14% and 39% overhead with the AMD and Intel patches respectively.

39% performance loss for Intel CPUs!