Re: [PATCH v6 00/29] Warn on orphan section placement

[Kees Cook]

On Tue, Sep 01, 2020 at 10:16:47AM +0200, Ingo Molnar wrote:
> 
> * Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> 
> > 
> > * Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> > 
> > > 
> > > * Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> > > 
> > > > On Fri, Aug 21, 2020 at 12:42:41PM -0700, Kees Cook wrote:
> > > > > Hi Ingo,
> > > > > 
> > > > > Based on my testing, this is ready to go. I've reviewed the feedback on
> > > > > v5 and made a few small changes, noted below.
> > > > 
> > > > If no one objects, I'll pop this into my tree for -next. I'd prefer it
> > > > go via -tip though! :)
> > > > 
> > > > Thanks!
> > > 
> > > I'll pick it up today, it all looks very good now!
> > 
> > One thing I found in testing is that it doesn't handler older LD 
> > versions well enough:
> > 
> >   ld: unrecognized option '--orphan-handling=warn'

Oh! Uhm, yikes. Thanks for noticing this.

> > Could we just detect the availability of this flag, and emit a warning 
> > if it doesn't exist but otherwise not abort the build?

Yeah, I'll respin those patches.

> > This is with:
> > 
> >   GNU ld version 2.25-17.fc23

(At best, this is from 2015 ... but yes, min binutils in 2.23.)

> 
> I've resolved this for now by not applying the 5 patches that add the 
> actual orphan section warnings:
> 
>   arm64/build: Warn on orphan section placement
>   arm/build: Warn on orphan section placement
>   arm/boot: Warn on orphan section placement
>   x86/build: Warn on orphan section placement
>   x86/boot/compressed: Warn on orphan section placement
> 
> The new asserts plus the actual fixes/enhancements are enough changes 
> to test for now in any case. :-)

Yup! I'll respin the enabling patches. Thanks again!

-- 
Kees Cook