286 lines
10 KiB
Diff
286 lines
10 KiB
Diff
commit 46d31980943d8be2f421c1e3276b265c7552636e
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Fri Mar 7 17:37:50 2025 +0100
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elf: Fix handling of symbol versions which hash to zero (bug 29190)
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This was found through code inspection. No application impact is
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known.
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Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Conflicts:
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elf/Makefile (fixup context)
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diff --git a/elf/Makefile b/elf/Makefile
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index a28ea58551ffd1d7..ba11f3a8b81e7218 100644
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--- a/elf/Makefile
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+++ b/elf/Makefile
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@@ -488,6 +488,7 @@ 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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@@ -927,6 +928,9 @@ 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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@@ -3014,3 +3018,20 @@ $(objpfx)tst-sprof-basic.out: tst-sprof-basic.sh $(objpfx)tst-sprof-basic
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'$(run-program-env)' > $@; \
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$(evaluate-test)
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generated += tst-sprof-mod.so.profile
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+
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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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diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
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index 94ae2d0c46696118..4c882bdd173a835d 100644
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--- a/elf/dl-lookup.c
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+++ b/elf/dl-lookup.c
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@@ -112,12 +112,22 @@ 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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+
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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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diff --git a/elf/dl-version.c b/elf/dl-version.c
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index 914955c2a832e573..982229c32c50d470 100644
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--- a/elf/dl-version.c
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+++ b/elf/dl-version.c
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@@ -351,6 +351,13 @@ _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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+
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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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return result;
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diff --git a/elf/tst-version-hash-zero-linkmod.c b/elf/tst-version-hash-zero-linkmod.c
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new file mode 100644
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index 0000000000000000..15e2506d0111bc7e
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--- /dev/null
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+++ b/elf/tst-version-hash-zero-linkmod.c
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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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+
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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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+
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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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+
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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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+
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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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diff --git a/elf/tst-version-hash-zero-linkmod.map b/elf/tst-version-hash-zero-linkmod.map
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new file mode 100644
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index 0000000000000000..2dba7c22d7ea7d09
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--- /dev/null
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+++ b/elf/tst-version-hash-zero-linkmod.map
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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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+
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+OTHER_VERSION {
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+ global: global_variable;
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+} Base;
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diff --git a/elf/tst-version-hash-zero-mod.c b/elf/tst-version-hash-zero-mod.c
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new file mode 100644
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index 0000000000000000..ac6b0dc4a57b5775
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--- /dev/null
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+++ b/elf/tst-version-hash-zero-mod.c
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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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+
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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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+
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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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+
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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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+
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+/* The symbol version is assigned by version script. */
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+int global_variable;
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diff --git a/elf/tst-version-hash-zero-mod.map b/elf/tst-version-hash-zero-mod.map
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new file mode 100644
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index 0000000000000000..41eaff79147a8fcd
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--- /dev/null
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+++ b/elf/tst-version-hash-zero-mod.map
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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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+
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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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+
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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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diff --git a/elf/tst-version-hash-zero-refmod.c b/elf/tst-version-hash-zero-refmod.c
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new file mode 100644
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index 0000000000000000..cd8b3dcef5b82012
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--- /dev/null
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+++ b/elf/tst-version-hash-zero-refmod.c
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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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+
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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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+
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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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+
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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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+
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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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diff --git a/elf/tst-version-hash-zero.c b/elf/tst-version-hash-zero.c
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new file mode 100644
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index 0000000000000000..66a0db4f51fa0e10
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--- /dev/null
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+++ b/elf/tst-version-hash-zero.c
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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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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+
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+ xdlclose (handle);
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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