[PATCH 0/2] Predictable ELF destructor ordering

[Stafford Horne]

On Mon, Dec 20, 2021, 10:20 PM Florian Weimer <fweimer@redhat.com> wrote:

> * Stafford Horne:
>
> > On Tue, Dec 14, 2021 at 10:01:57PM +0100, Florian Weimer via Libc-alpha
> wrote:
> >> These patches remove the dependency sorting from dlclose and process
> >> shutdown, so that destructor order is the reverse of constructor order
> >> in more cases (always if the process does not call dlclose).
> >>
> >> Tested on i686-linux-gnu and x86_64-linux-gnu.
> >>
> >> I would like to include this in glibc 2.35 if possible, among the other
> >> dependency sorting changes.
> >>
> >> I believe this fixes bugs 15311 and 15903.
> >>
> >> Florian Weimer (2):
> >>   elf: Do not rely on relocation dependencies for destructor sorting
> >>   elf: Always call destructors in reverse constructor order
> >>
> >>  elf/dl-close.c             | 130 +++++++++++++---------
> >>  elf/dl-deps.c              |   3 +-
> >>  elf/dl-fini.c              | 216 ++++++++++++++-----------------------
> >>  elf/dl-init.c              |  14 +++
> >>  elf/dl-sort-maps.c         | 105 ++----------------
> >>  elf/dso-sort-tests-1.def   |   6 +-
> >>  include/link.h             |   4 +
> >>  sysdeps/generic/ldsodefs.h |   6 +-
> >>  8 files changed, 194 insertions(+), 290 deletions(-)
> >
> > Hi Florian,
> >
> > This does seem to fix an issue for me in the OpenRISC port.  Discussed
> [1] in
> > the OpenRISC port thread.  It fixes:
> >
> >   elf/tst-bz15311
> >
> > Failure details in tst-bz15311.out (fixed with these patches) [2].
> >
> > However this also seems to break:
> >
> >   elf/tst-glibc-hwcaps-prepend-cache
> >
> > I am not able to get much detail from the failure other than a SIGDEGV
> > in fork, I then bisected it to these patches I have on my branch to
> > fix elf/tst-bz15311.  Let me know if I can help.
>
> What are the DT_NEEDED entries on the shared objects, and the run-time
> relocations?  I suspect you must have some unexpected dependency which
> confuses the old sorting code.
>
> The elf/tst-glibc-hwcaps-prepend-cache failure is very suspicious, it
> really should not happen.  Would you be able to debug it further?
>


Hi Florian

After further debugging I found i cannot reproduce this after a full
toolchain rebuild.

I will leave this to a bad environment setup on my side. Sorry for the noise

-Stafford