[Bug dynamic-link/17833] STB_GNU_UNIQUE symbols can lead to wrong behaviour of the dynamic loader

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=17833

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=02d5e5d94a78d32e940dfb3b58ab7f06c31b0f76

commit 02d5e5d94a78d32e940dfb3b58ab7f06c31b0f76
Author: Pavel Kopyl <p.kopyl@samsung.com>
Date:   Tue Jul 7 18:45:46 2015 +0300

    Add forced deletion support to _dl_close_worker

    https://sourceware.org/bugzilla/show_bug.cgi?id=17833

    I've a shared library that contains both undefined and unique symbols.
    Then I try to call the following sequence of dlopen:

    1. dlopen("./libfoo.so", RTLD_NOW)
    2. dlopen("./libfoo.so", RTLD_LAZY | RTLD_GLOBAL)

    First dlopen call terminates with error because of undefined symbols,
    but STB_GNU_UNIQUE ones set DF_1_NODELETE flag and hence block library
    in the memory.

    The library goes into inconsistent state as several structures remain
    uninitialized. For instance, relocations for GOT table were not performed.

    By the time of second dlopen call this library looks like as it would be
    fully initialized but this is not true: any call through incorrect GOT
    table leads to segmentation fault.  On some systems this inconsistency
    triggers assertions in the dynamic linker.

    This patch adds a parameter to _dl_close_worker to implement forced object
    deletion in case of dlopen() failure:

    1. Clears DF_1_NODELETE bit if forced, to allow library to be removed from
    memory.
    2. For each unique symbol that is defined in this object clears
    appropriate entry in _ns_unique_sym_table.

        [BZ #17833]
        * elf/Makefile (tests): Add tst-nodelete.
        (modules-names): Add tst-nodelete-uniquemod.
        (tst-nodelete-uniquemod.so-no-z-defs): New.
        (tst-nodelete-rtldmod.so-no-z-defs): Likewise.
        (tst-nodelete-zmod.so-no-z-defs): Likewise.
        ($(objpfx)tst-nodelete): Likewise.
        ($(objpfx)tst-nodelete.out): Likewise.
        (LDFLAGS-tst-nodelete): Likewise.
        (LDFLAGS-tst-nodelete-zmod.so): Likewise.
        * elf/dl-close.c (_dl_close_worker): Add a parameter to
        implement forced object deletion.
        (_dl_close): Pass false to _dl_close_worker.
        * elf/dl-open.c (_dl_open): Pass true to _dl_close_worker.
        * elf/tst-nodelete.cc: New file.
        * elf/tst-nodeletelib.cc: Likewise.
        * elf/tst-znodeletelib.cc: Likewise.
        * include/dlfcn.h (_dl_close_worker): Add a new parameter.

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog                     |   22 +++++++++++++++++
 NEWS                          |   26 ++++++++++----------
 elf/Makefile                  |   17 ++++++++++++-
 elf/dl-close.c                |   33 +++++++++++++++++++++++++-
 elf/dl-open.c                 |    2 +-
 elf/tst-nodelete-rtldmod.cc   |    6 +++++
 elf/tst-nodelete-uniquemod.cc |   14 +++++++++++
 elf/tst-nodelete-zmod.cc      |    6 +++++
 elf/tst-nodelete.cc           |   51 +++++++++++++++++++++++++++++++++++++++++
 elf/tst-znodelete-zlib.cc     |    6 +++++
 include/dlfcn.h               |    3 +-
 11 files changed, 167 insertions(+), 19 deletions(-)
 create mode 100644 elf/tst-nodelete-rtldmod.cc
 create mode 100644 elf/tst-nodelete-uniquemod.cc
 create mode 100644 elf/tst-nodelete-zmod.cc
 create mode 100644 elf/tst-nodelete.cc
 create mode 100644 elf/tst-znodelete-zlib.cc

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