Linux + GCC/Clang Patches Coming For Straight-Line Speculation Mitigation On x86/x86_64

[phoronix]

Phoronix: Linux + GCC/Clang Patches Coming For Straight-Line Speculation Mitigation On x86/x86_64

Disclosed last year by Arm was their processors affected by a straight-line speculation vulnerability. In this case the processor could speculatively execute instructions linearly in memory past an unconditional change in control flow. There has been talk about possible straight-line speculation on x86/x86_64 but without any action while now GCC and LLVM/Clang compiler developers along with Linux kernel developers are preparing such mitigation support...

https://www.phoronix.com/scan.php?page=news_item&px=Straight-Line-Speculation-x86

[Developer12]

People talking about it as if it's hypothetical, but as soon as the patches have landed I'm sure we'll discover it's not hypothetical at all.

People hate these mitigations and they hate putting in all the work to implement them, so there's no way they'd bother with all this patching in GCC/LLVM/the kernel/etc unless there was a damn good reason for it.

[debrouxl]

Indeed, with the combination of toolchain people implementing such functionality and kernel people wanting to use it (and helping debug the implementations), it's very likely not to be an hypothetical issue. At this stage, it might be a bit late for a disclosure early next month, but why not in early December or at worst early January, like the original batch of speculation-related issues.

BTW: https://mobile.twitter.com/grsecurit...17390689619978 states that grsec has been providing a mitigation for straight-line speculation issues since over a year before the ARM advisory.