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posted by martyb on Friday June 05 2020, @08:40AM   Printer-friendly
from the help-less,-please dept.

Linus Torvalds rejects 'beyond stupid' AWS-made Linux patch for Intel CPU Snoop attack

Linux kernel head Linus Torvalds has trashed a patch from Amazon Web Services (AWS) engineers that was aimed at mitigating the Snoop attack on Intel CPUs discovered by an AWS engineer earlier this year. [...] AWS engineer Pawel Wieczorkiewicz discovered a way to leak data from an Intel CPU's memory via its L1D cache, which sits in CPU cores, through 'bus snooping' – the cache updating operation that happens when data is modified in L1D.

In the wake of the disclosure, AWS engineer Balbir Singh proposed a patch for the Linux kernel for applications to be able to opt in to flush the L1D cache when a task is switched out. [...] The feature would allow applications on an opt-in basis to call prctl(2) to flush the L1D cache for a task once it leaves the CPU, assuming the hardware supports it.

But, as spotted by Phoronix, Torvalds believes the patch will allow applications that opt in to the patch to degrade CPU performance for other applications.

"Because it looks to me like this basically exports cache flushing instructions to user space, and gives processes a way to just say 'slow down anybody else I schedule with too'," wrote Torvalds yesterday. "In other words, from what I can tell, this takes the crazy 'Intel ships buggy CPU's and it causes problems for virtualization' code (which I didn't much care about), and turns it into 'anybody can opt in to this disease, and now it affects even people and CPU's that don't need it and configurations where it's completely pointless'."

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  • (Score: 0) by Anonymous Coward on Friday June 05 2020, @06:51PM (3 children)

    by Anonymous Coward on Friday June 05 2020, @06:51PM (#1003888)

    Amazon are shits and scammers - from experience, I don't trust anything from them. [...]

    I bought some legal anime DVDs from them along time ago. They tipped off local law enforcement about my purchase, and my life was completely destroyed as a result. I lost my job, with no hope of future employment. The neighborhood I reside in became infested with cops, lying-in-wait for me to commit some criminal act. Word gets around, & now I'm regarded by people I've never even met as a pedo & a stalker. Presumed guilty until death. I had no criminal record then, & still don't. I'm not a registered sex offender, either. Watch what you buy from Amazon. It could cost you your life.

  • (Score: 0) by Anonymous Coward on Friday June 05 2020, @07:03PM

    by Anonymous Coward on Friday June 05 2020, @07:03PM (#1003897)

    legal anime DVDs

    Cool story Kurt []

  • (Score: 0) by Anonymous Coward on Friday June 05 2020, @07:14PM

    by Anonymous Coward on Friday June 05 2020, @07:14PM (#1003902)

    I bought some legal anime DVDs

    Not pirating fansubs like a well-adjusted weeb? You deserved the jmichaelhudson treatment.

  • (Score: 2) by Bot on Friday June 05 2020, @07:24PM

    by Bot (3902) on Friday June 05 2020, @07:24PM (#1003907) Journal

    So, consuming material is a crime while distributing it for profit isn't?
    Anyway you should have kept the DVD sealed until they were 18 year old, pal.

    Account abandoned.