Red Hat has been made aware of an additional spectre-V1 like attack vector, requiring updates to the Linux kernel. This additional attack vector builds on existing software fixes shipped in previous kernel updates. This vulnerability only applies to x86-64 systems using either Intel or AMD processors.
This issue has been assigned CVE-2019-1125 and is rated Moderate.
An unprivileged local attacker can use these flaws to bypass conventional memory security restrictions to gain read access to privileged memory that would otherwise be inaccessible.
Microsoft silently issued patches for the new speculative execution vulnerability in its July 2019 Patch Tuesday security update which was discovered and responsibly disclosed by researchers at security firm Bitdefender.
Meanwhile, Google has also prepared a patch to fix this vulnerability in its ChromeOS 4.19 with a soon-to-be-released update, describing the flaw as:
"An attacker can train the branch predictor to speculatively skip the swapgs path for an interrupt or exception. If they initialize the GS register to a user-space value, if the swapgs is speculatively skipped, subsequent GS-related percpu accesses in the speculation window will be done with the attacker-controlled GS value. This could cause privileged memory to be accessed and leaked."
i skipped quoting anything about redhat for obvious reasons.
Remember the golden rule of statistics: A personal sample size of one is a sufficient basis upon which to draw universal conclusions.
If you need help: Upload the computer to Dropbox and provide a link to it so others may download it to examine and give advice for repairs.
Note that, on Intel, a similar attack exists in the above gadget when coming from kernel space, if the swapgs gets speculatively executed to switch back to the user GS. On AMD, this variant isn't possible because swapgs is serializing with respect to future GS-based accesses.
Microsoft silently patched the vulnerability during last month's update Tuesday. Microsoft said the fix works by changing how the CPU speculatively accesses memory.
Bold for emphasis.
Is there a performance impact because of this? As Phoronix says, probably, let's see.
The Bitdefender paper said researchers first reported the vulnerability to Intel 12 months ago, on August 7, 2018. Intel responded three weeks later by saying it already knew of the vulnerability and had no plans to fix it. Bitdefender said it spent the next eight months insisting to Intel that the behavior was problematic. Intel finally confirmed the leak of kernel memory on April 2 and indicated that a fix would come from fixes in operating systems.
How many CPUs does Intel want to sell with this behaviour?