[Bug dynamic-link/22745] _nptl_setxid can loop forever if a dlmopen namespace tries to initialise pthreads after the main namespace does

[Bug dynamic-link/22745] _nptl_setxid can loop forever if a dlmopen namespace tries to initialise pthreads after the main namespace does

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=22745

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |fweimer at redhat dot com
             Status|UNCONFIRMED                 |RESOLVED
   Target Milestone|---                         |2.34
         Resolution|---                         |FIXED

--- Comment #15 from Florian Weimer <fweimer at redhat dot com> ---
I believe we fixed this in glibc 2.34 with this commit:

commit 90d7e7e5bd3b0683a27c658388b6515ce950c78e
Author: Florian Weimer <fweimer@redhat.com>
Date:   Wed Apr 21 19:49:51 2021 +0200

    elf: Introduce __tls_init_tp for second-phase TCB initialization

    TLS_INIT_TP is processor-specific, so it is not a good place to
    put thread library initialization code (it would have to be repeated
    for all CPUs).  Introduce __tls_init_tp as a separate function,
    to be called immediately after TLS_INIT_TP.  Move the existing
    stack list setup code for NPTL to this function.

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

It depends on GL (dl_stack_user), which was introduced by:

commit 1daccf403b1bd86370eb94edca794dc106d02039
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon Nov 16 19:33:30 2020 +0100

    nptl: Move stack list variables into _rtld_global

    Now __thread_gscope_wait (the function behind THREAD_GSCOPE_WAIT,
    formerly __wait_lookup_done) can be implemented directly in ld.so,
    eliminating the unprotected GL (dl_wait_lookup_done) function
    pointer.

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Plus some other changes that eventually eliminate late libpthread
initialization. With late initialization completely gone, dlmopen or static
dlmopen no longer clobbers the TCB.

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