204 lines
6.1 KiB
Diff
204 lines
6.1 KiB
Diff
commit c1560f3f75c0e892b5522c16f91b4e303f677094
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Wed Nov 6 10:33:44 2024 +0100
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elf: Switch to main malloc after final ld.so self-relocation
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Before commit ee1ada1bdb8074de6e1bdc956ab19aef7b6a7872
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("elf: Rework exception handling in the dynamic loader
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[BZ #25486]"), the previous order called the main calloc
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to allocate a shadow GOT/PLT array for auditing support.
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This happened before libc.so.6 ELF constructors were run, so
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a user malloc could run without libc.so.6 having been
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initialized fully. One observable effect was that
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environ was NULL at this point.
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It does not seem to be possible at present to trigger such
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an allocation, but it seems more robust to delay switching
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to main malloc after ld.so self-relocation is complete.
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The elf/tst-rtld-no-malloc-audit test case fails with a
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2.34-era glibc that does not have this fix.
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Reviewed-by: DJ Delorie <dj@redhat.com>
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Conflicts:
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elf/Makefile (fixup context)
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elf/rtld.c (Align change with glibc-RHEL-48820-1)
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diff --git a/elf/Makefile b/elf/Makefile
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index 41adea8d1c6d13ca..0c8e0d794bac640f 100644
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--- a/elf/Makefile
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+++ b/elf/Makefile
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@@ -439,6 +439,9 @@ tests += \
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tst-recursive-tls \
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tst-relsort1 \
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tst-ro-dynamic \
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+ tst-rtld-no-malloc \
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+ tst-rtld-no-malloc-audit \
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+ tst-rtld-no-malloc-preload \
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tst-rtld-run-static \
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tst-single_threaded \
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tst-single_threaded-pthread \
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@@ -2896,3 +2899,9 @@ tst-tls22-mod2.so-no-z-defs = yes
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tst-tls22-mod2-gnu2.so-no-z-defs = yes
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$(objpfx)tst-dlopen-sgid.out: $(objpfx)tst-dlopen-sgid-mod.so
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+
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+# Reuse an audit module which provides ample debug logging.
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+tst-rtld-no-malloc-audit-ENV = LD_AUDIT=$(objpfx)tst-auditmod1.so
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+
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+# Any shared object should do.
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+tst-rtld-no-malloc-preload-ENV = LD_PRELOAD=$(objpfx)tst-auditmod1.so
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diff --git a/elf/dl-support.c b/elf/dl-support.c
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index 1fea55c443505890..00abc2d8056c78b0 100644
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--- a/elf/dl-support.c
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+++ b/elf/dl-support.c
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@@ -353,8 +353,7 @@ _dl_non_dynamic_init (void)
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}
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/* Setup relro on the binary itself. */
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- if (_dl_main_map.l_relro_size != 0)
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- _dl_protect_relro (&_dl_main_map);
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+ _dl_protect_relro (&_dl_main_map);
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}
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#ifdef DL_SYSINFO_IMPLEMENTATION
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diff --git a/elf/rtld.c b/elf/rtld.c
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index 711bb77d70da6563..3436dd918e699080 100644
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--- a/elf/rtld.c
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+++ b/elf/rtld.c
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@@ -2495,26 +2495,23 @@ dl_main (const ElfW(Phdr) *phdr,
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if (! prelinked)
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{
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- /* Re-relocate ourselves with user-controlled symbol definitions.
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-
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- We must do this after TLS initialization in case after this
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- re-relocation, we might call a user-supplied function
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- (e.g. calloc from _dl_relocate_object) that uses TLS data. */
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-
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- /* The malloc implementation has been relocated, so resolving
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- its symbols (and potentially calling IFUNC resolvers) is safe
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- at this point. */
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- __rtld_malloc_init_real (main_map);
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-
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/* Likewise for the locking implementation. */
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__rtld_mutex_init ();
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+ /* Re-relocate ourselves with user-controlled symbol definitions. */
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+
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RTLD_TIMING_VAR (start);
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rtld_timer_start (&start);
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- /* Mark the link map as not yet relocated again. */
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- GL(dl_rtld_map).l_relocated = 0;
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- _dl_relocate_object (&GL(dl_rtld_map), main_map->l_scope, 0, 0);
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+ _dl_relocate_object_no_relro (&GL(dl_rtld_map), main_map->l_scope, 0, 0);
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+
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+ /* The malloc implementation has been relocated, so resolving
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+ its symbols (and potentially calling IFUNC resolvers) is safe
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+ at this point. */
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+ __rtld_malloc_init_real (main_map);
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+
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+ if (GL(dl_rtld_map).l_relro_size != 0)
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+ _dl_protect_relro (&GL(dl_rtld_map));
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rtld_timer_accum (&relocate_time, start);
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}
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diff --git a/elf/tst-rtld-no-malloc-audit.c b/elf/tst-rtld-no-malloc-audit.c
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new file mode 100644
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index 0000000000000000..a028377ad1fea027
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--- /dev/null
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+++ b/elf/tst-rtld-no-malloc-audit.c
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@@ -0,0 +1 @@
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+#include "tst-rtld-no-malloc.c"
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diff --git a/elf/tst-rtld-no-malloc-preload.c b/elf/tst-rtld-no-malloc-preload.c
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new file mode 100644
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index 0000000000000000..a028377ad1fea027
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--- /dev/null
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+++ b/elf/tst-rtld-no-malloc-preload.c
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@@ -0,0 +1 @@
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+#include "tst-rtld-no-malloc.c"
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diff --git a/elf/tst-rtld-no-malloc.c b/elf/tst-rtld-no-malloc.c
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new file mode 100644
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index 0000000000000000..5f24d4bd72c4af0c
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--- /dev/null
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+++ b/elf/tst-rtld-no-malloc.c
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@@ -0,0 +1,76 @@
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+/* Test that program loading does not call malloc.
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+ Copyright (C) 2024 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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+
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+#include <string.h>
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+#include <unistd.h>
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+
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+static void
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+print (const char *s)
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+{
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+ const char *end = s + strlen (s);
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+ while (s < end)
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+ {
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+ ssize_t ret = write (STDOUT_FILENO, s, end - s);
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+ if (ret <= 0)
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+ _exit (2);
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+ s += ret;
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+ }
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+}
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+
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+static void __attribute__ ((noreturn))
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+unexpected_call (const char *function)
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+{
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+ print ("error: unexpected call to ");
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+ print (function);
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+ print ("\n");
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+ _exit (1);
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+}
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+
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+/* These are the malloc functions implement in elf/dl-minimal.c. */
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+
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+void
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+free (void *ignored)
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+{
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+ unexpected_call ("free");
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+}
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+
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+void *
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+calloc (size_t ignored1, size_t ignored2)
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+{
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+ unexpected_call ("calloc");
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+}
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+
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+void *
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+malloc (size_t ignored)
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+{
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+ unexpected_call ("malloc");
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+}
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+
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+void *
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+realloc (void *ignored1, size_t ignored2)
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+{
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+ unexpected_call ("realloc");
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+}
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+
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+int
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+main (void)
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+{
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+ /* Do not use the test wrapper, to avoid spurious malloc calls from it. */
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+ return 0;
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+}
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