Linux Developer Is Unhappy with Amazon
June 17, 2020
Who doesn’t love Amazon? Maybe the person credited with developing Linux? That would be Linus Torvalds, developer of note.
No one pays attention to insults on the Internet unless someone with clout says them. The IT community definitely paid attention to the head of the Linux kernelLinus Torvalds when he said, “Linus Torvalds Rejects ‘Beyond Stupid’ AWS-Made Linux Patch For Intel CPU Snoop Attack” reports ZDNet.
In early 2020, Snoop launched attacks on Intel andCore CPUs and AWS discovered it. The attack causes CPUs to leak data from its L1D cache via bus snooping—a cache-updating operation that happens when the L1D modifies data. AWS developed a patch for the Linux kernel that would allow applications to opt in to flush the L1D cache when a task is switched out. Torvalds thinks the patch would degrade performance in other applications. Torvalds said:
“ ‘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’…‘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’.
‘I don’t want some application to go ‘Oh, I’m _soo_ special and pretty and such a delicate flower, that I want to flush the L1D on every task switch, regardless of what CPU I am on, and regardless of whether there are errata or not. Because that app isn’t just slowing down itself, it’s slowing down others too.’’
Torvalds also think the patch is crazy because a hack could inhabit another core within the CPU and attack the L1 cache before its flushed. Another fun word he used was pseudo-security.
Usually “pseudo” is reserved for science, but this works too.
Whitney Grace, June 17, 2020
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