Re: [PATCH v3 16/16] objtool: Validate kCFI calls

[Josh Poimboeuf]

On Mon, Jul 14, 2025 at 12:20:27PM +0200, Peter Zijlstra wrote:
> Validate that all indirect calls adhere to kCFI rules. Notably doing
> nocfi indirect call to a cfi function is broken.
> 
> Apparently some Rust 'core' code violates this and explodes when ran
> with FineIBT.
> 
> All the ANNOTATE_NOCFI_SYM sites are prime targets for attackers.
> 
>  - runtime EFI is especially henous because it also needs to disable
>    IBT. Basically calling unknown code without CFI protection at
>    runtime is a massice security issue.
> 
>  - Kexec image handover; if you can exploit this, you get to keep it :-)
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

-- 
Josh