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Interesting technique by Todd Mortimer to reduce the number of gadgets on x86 even further: marc.info/?l=openbsd-tech&m=15

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Nice! Todd Mortimer has committed his patch for into -current.

"This change removes about 3% of total gadgets from the kernel, but about 6% of unique gadgets."

marc.info/?l=openbsd-cvs&m=151

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Follow-up x86 "ROP friendly" gadget reduction framework for , which can be extended. Impressive work by Todd Mortimer! 😎 marc.info/?l=openbsd-cvs&m=152

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"In this way RETGUARD is an improved stack protector, since the cookies are per-function."

"In the kernel, this has the effect of removing approximately 50% of total gadgets, and 15% of unique ROP gadgets compared to the 6.3 release kernel."

😎

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@canadianbryan That's really interesting. Do you think upstream might consider applying that sort of patch, or will it stay OpenBSD-only?

@kellerfuchs @canadianbryan I know with trap sleds the plan was to try it out for a while and then upstream it.
Basically, OpenBSD folks will shake out the bugs first.

@kurtm @canadianbryan
I was going to write “and the world will thank you for it”, but I think the correct word is “should, but won't”. :sob:

Thanks for doing it anyhow.

@kurtm @kellerfuchs Indeed, there's been a lot of communication between the OpenBSD and llvm/clang developers previously, Todd has expressed interest before. I guess we'll see! 😃

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