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Re: [PATCH] Linux/x86: Support shadow stack pointer in setjmp/longjmp

On Tue, 19 Dec 2017, Zack Weinberg wrote:

> On Tue, Dec 19, 2017 at 8:41 AM, H.J. Lu <> wrote:
> >>> That doesn't seem to be one of the patches you listed as a dependency of
> >>> this one.  Does that not matter because __SHSTK__ can never be defined
> >>> when building glibc unless that other patch is in glibc?
> >>
> >> I submitted the setjmp patch to show how backward binary compatibility
> >> is preserved.   Yes, setjmp is unchanged if we aren't building glibc with
> >> CET enabled, which will be done in a separate patch.
> >>
> >
> > As I mentioned, we need room in jmp_buf to save and restore shadow stack
> > pointer in setjmp/longjmp.  Since only Linux/x86 jmp_buf has a space for
> > shadow stack pointer, this setjmp/longjmp patch is only for Linux/x86.
> >
> > I am checking it in today.
> I don't think you have consensus. You haven't answered most of

HJ, I think you're persistently showing problems with judging consensus, 
and henceforth should *only* commit patches that at least one maintainer 
has explicitly approved in the exact form in which you wish to commit 
them, rather than trying to judge a patch to have consensus without such 
an explicit approval.

> Joseph's questions, and it is not clear to me whether Florian
> considers his objection resolved.  This is not a high-priority bugfix.

Furthermore, the points about missing kernel interfaces and the many 
FIXMEs in the substantive CET patch strongly suggest the main feature this 
is meant to enable will not be ready for 2.27.

Joseph S. Myers

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