mirror of git://sourceware.org/git/glibc.git
elf: Fix handling of symbol versions which hash to zero (bug 29190)
This was found through code inspection. No application impact is known. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer
parent
59dc232df2
commit
46d3198094
21
elf/Makefile
21
elf/Makefile
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@ -498,6 +498,7 @@ tests += \
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tst-unique2 \
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tst-unwind-ctor \
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tst-unwind-main \
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tst-version-hash-zero \
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unload3 \
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unload4 \
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unload5 \
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@ -1035,6 +1036,9 @@ modules-names += \
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tst-unique2mod1 \
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tst-unique2mod2 \
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tst-unwind-ctor-lib \
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tst-version-hash-zero-linkmod \
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tst-version-hash-zero-mod \
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tst-version-hash-zero-refmod \
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unload2dep \
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unload2mod \
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unload3mod1 \
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@ -3412,3 +3416,20 @@ $(objpfx)tst-nolink-libc-2: $(objpfx)tst-nolink-libc.o
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-Wl,--dynamic-linker=$(objpfx)ld.so
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$(objpfx)tst-nolink-libc-2.out: $(objpfx)tst-nolink-libc-2 $(objpfx)ld.so
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$< > $@ 2>&1; $(evaluate-test)
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$(objpfx)tst-version-hash-zero.out: \
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$(objpfx)tst-version-hash-zero-mod.so \
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$(objpfx)tst-version-hash-zero-refmod.so
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LDFLAGS-tst-version-hash-zero-mod.so = \
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-Wl,--version-script=tst-version-hash-zero-mod.map
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# The run-time test module tst-version-hash-zero-refmod.so is linked
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# to a stub module, tst-version-hash-zero-linkmod.so, to produce an
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# expected relocation error.
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$(objpfx)tst-version-hash-zero-refmod.so: \
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$(objpfx)tst-version-hash-zero-linkmod.so
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LDFLAGS-tst-version-hash-zero-linkmod.so = \
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-Wl,--version-script=tst-version-hash-zero-linkmod.map \
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-Wl,--soname=tst-version-hash-zero-mod.so
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$(objpfx)tst-version-hash-zero-refmod.so: \
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$(objpfx)tst-version-hash-zero-linkmod.so
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tst-version-hash-zero-refmod.so-no-z-defs = yes
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@ -100,12 +100,22 @@ check_match (const char *const undef_name,
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/* We can match the version information or use the
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default one if it is not hidden. */
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ElfW(Half) ndx = verstab[symidx] & 0x7fff;
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if ((map->l_versions[ndx].hash != version->hash
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|| strcmp (map->l_versions[ndx].name, version->name))
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&& (version->hidden || map->l_versions[ndx].hash
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|| (verstab[symidx] & 0x8000)))
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/* It's not the version we want. */
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return NULL;
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if (map->l_versions[ndx].hash == version->hash
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&& strcmp (map->l_versions[ndx].name, version->name) == 0)
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/* This is an exact version match. Return the symbol below. */
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;
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else
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{
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if (!version->hidden
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&& map->l_versions[ndx].name[0] == '\0'
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&& (verstab[symidx] & 0x8000) == 0
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&& (*num_versions)++ == 0)
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/* This is the global default version. Store it as a
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fallback match. */
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*versioned_sym = sym;
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return NULL;
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}
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}
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}
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else
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@ -357,6 +357,13 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode)
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ent = (ElfW(Verdef) *) ((char *) ent + ent->vd_next);
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}
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}
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/* The empty string has ELF hash zero. This avoids a NULL check
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before the version string comparison in check_match in
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dl-lookup.c. */
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for (unsigned int i = 0; i < map->l_nversions; ++i)
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if (map->l_versions[i].name == NULL)
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map->l_versions[i].name = "";
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}
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/* When there is a DT_VERNEED entry with libc.so on DT_NEEDED, issue
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@ -0,0 +1,22 @@
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/* Stub module for linking tst-version-hash-zero-refmod.so.
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Copyright (C) 2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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/* The version script assigns a different symbol version for the stub
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module. Loading the module with the incorrect version is expected
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to fail. */
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#include "tst-version-hash-zero-mod.c"
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@ -0,0 +1,7 @@
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Base {
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local: *;
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};
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OTHER_VERSION {
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global: global_variable;
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} Base;
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@ -0,0 +1,20 @@
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/* Test module with a zero version symbol hash.
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Copyright (C) 2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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/* The symbol version is assigned by version script. */
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int global_variable;
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@ -0,0 +1,13 @@
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Base {
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local: *;
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};
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/* Define the version so that tst-version-hash-zero-refmod.so passes
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the initial symbol version check. */
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OTHER_VERSION {
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} Base;
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/* This version string hashes to zero. */
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PPPPPPPPPPPP {
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global: global_variable;
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} Base;
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@ -0,0 +1,23 @@
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/* Test module that triggers a relocation failure in tst-version-hash-zero.
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Copyright (C) 2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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/* This is bound to global_variable@@OTHER_VERSION via
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tst-version-hash-zero-linkmod.so, but at run time, only
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global_variable@PPPPPPPPPPPP exists. */
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extern int global_variable;
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int *pointer_variable = &global_variable;
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@ -0,0 +1,56 @@
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/* Symbols with version hash zero should not match any version (bug 29190).
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Copyright (C) 2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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#include <support/check.h>
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#include <support/xdlfcn.h>
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#include <stddef.h>
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#include <string.h>
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static int
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do_test (void)
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{
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void *handle = xdlopen ("tst-version-hash-zero-mod.so", RTLD_NOW);
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/* This used to crash because some struct r_found_version entries
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with hash zero did not have valid version strings. */
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TEST_VERIFY (xdlvsym (handle, "global_variable", "PPPPPPPPPPPP") != NULL);
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/* Consistency check. */
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TEST_VERIFY (xdlsym (handle, "global_variable")
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== xdlvsym (handle, "global_variable", "PPPPPPPPPPPP"));
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/* This symbol version is supposed to be missing. */
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TEST_VERIFY (dlvsym (handle, "global_variable", "OTHER_VERSION") == NULL);
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/* tst-version-hash-zero-refmod.so references
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global_variable@@OTHER_VERSION and is expected to fail to load.
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dlvsym sets the hidden flag during lookup. Relocation does not,
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so this exercises a different failure case. */
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TEST_VERIFY_EXIT (dlopen ("tst-version-hash-zero-refmod.so", RTLD_NOW)
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== NULL);
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const char *message = dlerror ();
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if (strstr (message,
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": undefined symbol: global_variable, version OTHER_VERSION")
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== NULL)
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FAIL_EXIT1 ("unexpected dlopen failure: %s", message);
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xdlclose (handle);
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return 0;
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}
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#include <support/test-driver.c>
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