[Bug dynamic-link/28503] New: dl_iterate_phdr namespace violation

[Bug dynamic-link/28503] New: dl_iterate_phdr namespace violation

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28503

            Bug ID: 28503
           Summary: dl_iterate_phdr namespace violation
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dynamic-link
          Assignee: unassigned at sourceware dot org
          Reporter: fweimer at redhat dot com
  Target Milestone: ---

The program below aborts even though it does nothing wrong. The reason is that
the libgcc_s unwinder calls dl_iterate_phdr, which is not in the implementation
namespace, so the application should be able to define it in a different way.

#define _POSIX_SOURCE
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

void
dl_iterate_phdr (void)
{
  abort ();
}

static void *
thread_func (void *ignored)
{
  pthread_exit (NULL);
  return NULL;
}

int
main (void)
{
  pthread_t thr;
  if (pthread_create (&thr, NULL, thread_func, NULL) != 0)
    {
      puts ("pthread_create failed");
      return 1;
    }
  if (pthread_join (thr, NULL) != 0)
    {
      puts ("pthread_join failed");
      return 1;
    }
  return 0;
}

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[Bug dynamic-link/28503] dl_iterate_phdr namespace violation

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28503

--- Comment #1 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Florian Weimer <fw@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=5d28a8962dcb6ec056b81d730e3c6fb57185a210

commit 5d28a8962dcb6ec056b81d730e3c6fb57185a210
Author: Florian Weimer <fweimer@redhat.com>
Date:   Tue Dec 28 22:52:56 2021 +0100

    elf: Add _dl_find_object function

    It can be used to speed up the libgcc unwinder, and the internal
    _dl_find_dso_for_object function (which is used for caller
    identification in dlopen and related functions, and in dladdr).

    _dl_find_object is in the internal namespace due to bug 28503.
    If libgcc switches to _dl_find_object, this namespace issue will
    be fixed.  It is located in libc for two reasons: it is necessary
    to forward the call to the static libc after static dlopen, and
    there is a link ordering issue with -static-libgcc and libgcc_eh.a
    because libc.so is not a linker script that includes ld.so in the
    glibc build tree (so that GCC's internal -lc after libgcc_eh.a does
    not pick up ld.so).

    It is necessary to do the i386 customization in the
    sysdeps/x86/bits/dl_find_object.h header shared with x86-64 because
    otherwise, multilib installations are broken.

    The implementation uses software transactional memory, as suggested
    by Torvald Riegel.  Two copies of the supporting data structures are
    used, also achieving full async-signal-safety.

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

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