Re: [PATCH 1/2] x86/cfi: Fix ret_from_fork indirect calls

[Kees Cook]

On Thu, Jun 15, 2023 at 09:35:47PM +0200, Peter Zijlstra wrote:
> The ret_from_fork stub does an indirect call to the kthread function,
> but only knows about Retpolines. Instead of making the asm more
> complicated, punt to C and let the compiler figure it out.
> 
> Specifically, this makes it a proper kCFI indirect call when needed (in
> fact, it is nearly impossible to code a kCFI indirect call in asm).
> 
> This was the only callsite that was still calling func()+0 on regular
> indirect functions.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

I worry this creates a calling gadget, but I don't think it really
counts since it's just converting between two prototypes. Regardless:

Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook