forked from rpms/glibc
99 lines
3.7 KiB
Diff
99 lines
3.7 KiB
Diff
commit 9ffa50b26b0cb5d3043adf6d3d0b1ea735acc147
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Fri Dec 11 17:30:03 2020 +0100
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elf: Include libc.so.6 as main program in dependency sort (bug 20972)
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_dl_map_object_deps always sorts the initially loaded object first
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during dependency sorting. This means it is relocated last in
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dl_open_worker. This results in crashes in IFUNC resolvers without
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lazy bindings if libraries are preloaded that refer to IFUNCs in
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libc.so.6: the resolvers are called when libc.so.6 has not been
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relocated yet, so references to _rtld_global_ro etc. crash.
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The fix is to check against the libc.so.6 link map recorded by the
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__libc_early_init framework, and let it participate in the dependency
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sort.
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This fixes bug 20972.
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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Conflicts:
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elf/Makefile
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(Usual test backport differences.)
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diff --git a/elf/Makefile b/elf/Makefile
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index 67029930dd2cb461..fc9c685b9d23bb6c 100644
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--- a/elf/Makefile
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+++ b/elf/Makefile
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@@ -215,7 +215,7 @@ tests-internal += loadtest unload unload2 circleload1 \
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tst-tls3 tst-tls6 tst-tls7 tst-tls8 tst-dlmopen2 \
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tst-ptrguard1 tst-stackguard1 tst-libc_dlvsym \
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tst-create_format1 tst-tls-surplus tst-dl-hwcaps_split
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-tests-container += tst-pldd
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+tests-container += tst-pldd tst-preload-pthread-libc
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ifeq ($(build-hardcoded-path-in-tests),yes)
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tests += tst-dlopen-aout
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tst-dlopen-aout-no-pie = yes
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diff --git a/elf/dl-deps.c b/elf/dl-deps.c
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index 50f053a1586efdc3..007069f670eced95 100644
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--- a/elf/dl-deps.c
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+++ b/elf/dl-deps.c
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@@ -610,7 +610,12 @@ Filters not supported with LD_TRACE_PRELINKING"));
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memcpy (l_initfini, map->l_searchlist.r_list,
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nlist * sizeof (struct link_map *));
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- _dl_sort_maps (&l_initfini[1], nlist - 1, NULL, false);
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+ /* If libc.so.6 is the main map, it participates in the sort, so
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+ that the relocation order is correct regarding libc.so.6. */
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+ if (l_initfini[0] == GL (dl_ns)[l_initfini[0]->l_ns].libc_map)
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+ _dl_sort_maps (l_initfini, nlist, NULL, false);
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+ else
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+ _dl_sort_maps (&l_initfini[1], nlist - 1, NULL, false);
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/* Terminate the list of dependencies. */
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l_initfini[nlist] = NULL;
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diff --git a/elf/tst-preload-pthread-libc.c b/elf/tst-preload-pthread-libc.c
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new file mode 100644
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index 0000000000000000..48cb512a93f3da19
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--- /dev/null
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+++ b/elf/tst-preload-pthread-libc.c
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@@ -0,0 +1,36 @@
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+/* Test relocation ordering if the main executable is libc.so.6 (bug 20972).
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+ Copyright (C) 2020 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
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the 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; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <gnu/lib-names.h>
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+#include <stdio.h>
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+#include <support/support.h>
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+#include <unistd.h>
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+
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+int
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+main (void)
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+{
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+ char *libc = xasprintf ("%s/%s", support_slibdir_prefix, LIBC_SO);
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+ char *argv[] = { libc, NULL };
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+ char *envp[] = { (char *) "LD_PRELOAD=" LIBPTHREAD_SO,
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+ /* Relocation ordering matters most without lazy binding. */
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+ (char *) "LD_BIND_NOW=1",
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+ NULL };
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+ execve (libc, argv, envp);
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+ printf ("execve of %s failed: %m\n", libc);
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+ return 1;
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+}
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