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>Between Intel's numerous CPU bugs that they refused to refund customers for How do you propose this could work? Are side channel vulnerabilities in CPUs real

>Between Intel's numerous CPU bugs that they refused to refund customers for How do you propose this could work? Are side channel vulnerabilities in CPUs really bugs?

adrianN 9y ago
They promise modern process isolation and fail to deliver it. Their fixes reduce performance significantly. IANAL, but that sounds like a defective product.
- ryanlol 9y ago
  >They promise modern process isolation and fail to deliver it. Modern process isolation is not flawless, therefore it is not modern process isolation.
- wolfgke 9y ago
  > They promise modern process isolation and fail to deliver it. Before one makes such a statement, one has to define "modern process isolation" in a very formal way, so that not anybody (neither Intel nor the customer) can redefine the meaning as they desire. I am not aware that Intel gave such a formal definition that they claim to obey to (but perhaps fail). So any operating system can only rely on very weak guarantees for the processor to provide "isolation" (using quotes since I have not defined the term "isolation" formally). Thus the OS has to implement stronger isolation primitives that it desires by itself (by using the weak primitives that the processor provides).
eximius 9y ago
I mean, this one, yea. Speculative execution should not have side effects when wrong because it is Intel silently, sneakily breaking the model of how the CPU works (at least, if you only include the cache in how the PC works and not branch prediction). I would have expected, if I thought to ask, that items were not added to the cache or were removed from the cache if the branch was not retired.
- deleted 9y ago
  [deleted]
- EgoIncarnate 9y ago
  Removing items afterwords probably wouldn't work as you might be able stuff (instead of flush) the cache and figure out which line was emptied. Intel isn't being sneaky, speculative reading was a standard and accepted feature for out of order processors for over 20 years (remember it affects ARM,AMD,Apple,IBM etc as well). Speculative reading privileged memory while unprivileged was a big mistake though.
  - sverige 9y ago
    Intel's greatest PR success in this mess has been to conflate Meltdown with Spectre. Only Intel is affected by Meltdown because of their design, and it is a more easily exploited bug.
    - EgoIncarnate 9y ago
      Meltdown is not only Intel. Some ARM and Apple designed ARM processors are affected by Meltdown as well. https://en.wikipedia.org/wiki/Meltdown_(security_vulnerability)#Affected_hardware https://en.wikipedia.org/wiki/Meltdown_(security_vulnerabili...
      - makomk 9y ago
        There are no products on the market shipping with the one ARM-designed processor affected by Meltdown.
        EgoIncarnate 9y ago
        I think that's mainly out of luck. If the exploit had been discovered two years later, the story would likely be different. Apple has been much more ambitious with their ARM processor designs and has shipping iOS and AppleTV products affected by Meltdown. Shipping or not, it illustrates, that Intel was not unique.

>Between Intel's numerous CPU bugs that they refused to refund customers for How do you propose this could work? Are side channel vulnerabilities in CPUs really bugs?

adrianN 9y ago

They promise modern process isolation and fail to deliver it. Their fixes reduce performance significantly. IANAL, but that sounds like a defective product.

ryanlol 9y ago
>They promise modern process isolation and fail to deliver it. Modern process isolation is not flawless, therefore it is not modern process isolation.
wolfgke 9y ago
> They promise modern process isolation and fail to deliver it. Before one makes such a statement, one has to define "modern process isolation" in a very formal way, so that not anybody (neither Intel nor the customer) can redefine the meaning as they desire. I am not aware that Intel gave such a formal definition that they claim to obey to (but perhaps fail). So any operating system can only rely on very weak guarantees for the processor to provide "isolation" (using quotes since I have not defined the term "isolation" formally). Thus the OS has to implement stronger isolation primitives that it desires by itself (by using the weak primitives that the processor provides).

eximius 9y ago

I mean, this one, yea. Speculative execution should not have side effects when wrong because it is Intel silently, sneakily breaking the model of how the CPU works (at least, if you only include the cache in how the PC works and not branch prediction). I would have expected, if I thought to ask, that items were not added to the cache or were removed from the cache if the branch was not retired.

deleted 9y ago
[deleted]
EgoIncarnate 9y ago
Removing items afterwords probably wouldn't work as you might be able stuff (instead of flush) the cache and figure out which line was emptied. Intel isn't being sneaky, speculative reading was a standard and accepted feature for out of order processors for over 20 years (remember it affects ARM,AMD,Apple,IBM etc as well). Speculative reading privileged memory while unprivileged was a big mistake though.
- sverige 9y ago
  Intel's greatest PR success in this mess has been to conflate Meltdown with Spectre. Only Intel is affected by Meltdown because of their design, and it is a more easily exploited bug.
  - EgoIncarnate 9y ago
    Meltdown is not only Intel. Some ARM and Apple designed ARM processors are affected by Meltdown as well. https://en.wikipedia.org/wiki/Meltdown_(security_vulnerability)#Affected_hardware https://en.wikipedia.org/wiki/Meltdown_(security_vulnerabili...
    - makomk 9y ago
      There are no products on the market shipping with the one ARM-designed processor affected by Meltdown.
      - EgoIncarnate 9y ago
        I think that's mainly out of luck. If the exploit had been discovered two years later, the story would likely be different. Apple has been much more ambitious with their ARM processor designs and has shipping iOS and AppleTV products affected by Meltdown. Shipping or not, it illustrates, that Intel was not unique.