[Bug libc/27582] New: x86_64: IFUNC in static user programs may crash when built with -fstack-protector-all

[Bug libc/27582] New: x86_64: IFUNC in static user programs may crash when built with -fstack-protector-all

[siddhesh at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27582

            Bug ID: 27582
           Summary: x86_64: IFUNC in static user programs may crash when
                    built with -fstack-protector-all
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: siddhesh at sourceware dot org
                CC: drepper.fsp at gmail dot com
  Target Milestone: ---
            Target: x86-64

When an IFUNC is built with stack protector, the x86-64 startup code ends up
with a circular dependency where TLS initialization depends on IFUNC resolution
to complete and the IFUNC resolver depends on TLS setup to complete since the
stack canary is a TLS variable.

This is manifested in bug 25680 and bug 27555.  IFUNCs in the tests are
currently built with stack protector disabled but ideally this circular
dependency should be removed by making sure that TLS setup can be done without
IFUNCs.

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[Bug libc/27582] x86_64: IFUNC in static user programs may crash when built with -fstack-protector-all

[nick.alcock at oracle dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27582

Nick Alcock <nick.alcock at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nick.alcock at oracle dot com

--- Comment #1 from Nick Alcock <nick.alcock at oracle dot com> ---
Strong agreement, FWIW. This is obviously the right thing to do. I tried to do
just this when I implemented stack-protector support in the first place, but
got lost in a tangle and never got it to work without regressions elsewhere.
(In hindsight leaving it out was a good idea, because the whole area has
churned so much since then that anything I had got working would probably have
broken again!)

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[Bug libc/27582] x86_64: IFUNC in static user programs may crash when built with -fstack-protector-all

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=27582

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=25680,
                   |                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=27555
                 CC|                            |sam at gentoo dot org

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