Re:Spectre mitigations murder userspace performance
by userbinator on Saturday June 19, 2021 @05:44PM
(#27564733)
...making it even more unlikely the attack would find anything of value (or even recognisable as such) in a reasonable amount of time.
To use an analogy, these side-channel timing attacks are really a "looking for a needle in a haystack" (or heap...) situation, except that [1] you don't necessarily know what a needle looks like, and [2] the haystack is constantly changing. AFAIK all the PoCs shown so far relied on having a deep knowledge of the system and carefully constructed conditions.
If these attacks could undetectably dump all of your RAM in a few seconds, that would definitely be a huge concern. But they're more like being able to read a few bytes per second, from somewhere in the address space, with no idea what they are or where they're being read from, and no guarantee that they're even contiguous.
To use an analogy, these side-channel timing attacks are really a "looking for a needle in a haystack" (or heap...) situation, except that [1] you don't necessarily know what a needle looks like, and [2] the haystack is constantly changing. AFAIK all the PoCs shown so far relied on having a deep knowledge of the system and carefully constructed conditions.
If these attacks could undetectably dump all of your RAM in a few seconds, that would definitely be a huge concern. But they're more like being able to read a few bytes per second, from somewhere in the address space, with no idea what they are or where they're being read from, and no guarantee that they're even contiguous.