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.
The so-called 'Snoop-assisted L1 Data Sampling', or Snoop (CVE-2020-0550) attacks affecting a range of Intel Xeon and Core CPUs were disclosed in March.
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.
