Messages in this thread | | | Date | Mon, 17 Oct 2022 12:32:39 -0700 | From | Kees Cook <> | Subject | Re: upgrade the orphan section warning to a hard link error |
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On Mon, Oct 17, 2022 at 11:26:47AM -0700, Nathan Chancellor wrote: > It might be interesting to turn orphan sections into an error if > CONFIG_WERROR is set. Perhaps something like the following (FYI, not > even compile tested)? > > diff --git a/Makefile b/Makefile > index 0837445110fc..485f47fc2c07 100644 > --- a/Makefile > +++ b/Makefile > @@ -1119,7 +1119,7 @@ endif > # We never want expected sections to be placed heuristically by the > # linker. All sections should be explicitly named in the linker script. > ifdef CONFIG_LD_ORPHAN_WARN > -LDFLAGS_vmlinux += --orphan-handling=warn > +LDFLAGS_vmlinux += --orphan-handling=$(if $(CONFIG_WERROR),error,warn) > endif
Yes, this is much preferred.
> Outright turning the warning into an error with no escape hatch might be > too aggressive, as we have had these warnings triggered by new compiler > generated sections, such as in commit 848378812e40 ("vmlinux.lds.h: > Handle clang's module.{c,d}tor sections"). Unconditionally breaking the > build in these situations is unfortunate but the warnings do need to be > dealt with so I think having it error by default with the ability to > opt-out is probably worth doing. I do not have a strong opinion though.
Correct; the mandate from Linus (disregarding his addition of CONFIG_WERROR for all*config builds), is that we should avoid breaking builds. It wrecks bisection, it causes problems across compiler versions, etc.
So, yes, only on CONFIG_WERROR=y.
-- Kees Cook
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