Messages in this thread | | | Date | Tue, 18 Oct 2022 22:18:08 -0700 | From | Kees Cook <> | Subject | Re: [PATCH] x86/ibt: Implement FineIBT |
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On Tue, Oct 18, 2022 at 10:30:27PM +0200, Peter Zijlstra wrote: > On Tue, Oct 18, 2022 at 01:17:28PM -0700, Joao Moreira wrote: > > > > > > > Tangent: why are these nop instead of 0xcc? These bytes aren't > > > > executed > > > > ever are they? > > > > > > Because that's what the compiler gets us through > > > -fpatchable-function-entry. > > > > Is it useful to get the compiler to emit 0xcc with > > -fpatchable-function-entry under any circumstance? I can probably change > > that quickly if needed/useful. > > Having it emit 0xcc for the bytes in front of the symbol might be > interesting. It would mean a few kernel changes, but nothing too hard.
The world is pretty different with endbr, but I still always need big nop areas as giant "jump anywhere in here" targets. ;)
-- Kees Cook
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