216 lines
6.7 KiB
Diff
216 lines
6.7 KiB
Diff
From 6310d570bf20348135d09e1f9de84a9ae7d06f83 Mon Sep 17 00:00:00 2001
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From: Eyal Itkin <eyalit@checkpoint.com>
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Date: Thu, 2 Apr 2020 07:26:35 -0400
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Subject: Add tests for Safe-Linking
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Adding the test "tst-safe-linking" for testing that Safe-Linking works
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as expected. The test checks these 3 main flows:
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* tcache protection
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* fastbin protection
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* malloc_consolidate() correctness
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As there is a random chance of 1/16 that of the alignment will remain
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correct, the test checks each flow up to 10 times, using different random
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values for the pointer corruption. As a result, the chance for a false
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failure of a given tested flow is 2**(-40), thus highly unlikely.
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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diff --git a/malloc/Makefile b/malloc/Makefile
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index 984045b5b9..e22cbde22d 100644
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--- a/malloc/Makefile
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+++ b/malloc/Makefile
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@@ -39,6 +39,7 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
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tst-malloc-too-large \
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tst-malloc-stats-cancellation \
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tst-tcfree1 tst-tcfree2 tst-tcfree3 \
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+ tst-safe-linking \
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tests-static := \
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tst-interpose-static-nothread \
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diff --git a/malloc/tst-safe-linking.c b/malloc/tst-safe-linking.c
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new file mode 100644
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index 0000000000..067b6c09cf
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--- /dev/null
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+++ b/malloc/tst-safe-linking.c
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@@ -0,0 +1,179 @@
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+/* Test reporting of Safe-Linking caught errors.
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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 <signal.h>
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+#include <stdint.h>
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+#include <stdlib.h>
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+#include <memory.h>
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+#include <string.h>
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+#include <time.h>
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+#include <stdbool.h>
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+#include <support/capture_subprocess.h>
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+#include <support/check.h>
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+
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+/* Run CALLBACK and check that the data on standard error equals
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+ EXPECTED. */
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+static void
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+check (const char *test, void (*callback) (void *),
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+ const char *expected)
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+{
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+ int i, rand_mask;
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+ bool success = false;
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+ /* There is a chance of 1/16 that a corrupted pointer will be aligned.
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+ Try multiple times so that statistical failure will be improbable. */
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+ for (i = 0; i < 10 && !success; ++i)
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+ {
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+ rand_mask = rand () & 0xFF;
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+ struct support_capture_subprocess result
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+ = support_capture_subprocess (callback, &rand_mask);
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+ /* Did not crash, could happen. Try again. */
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+ if (strlen (result.err.buffer) == 0)
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+ continue;
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+ /* Crashed, must be the expected result. */
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+ if (strcmp (result.err.buffer, expected) != 0)
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+ {
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+ support_record_failure ();
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+ printf ("error: test %s unexpected standard error data\n"
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+ " expected: %s\n"
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+ " actual: %s\n",
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+ test, expected, result.err.buffer);
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+ }
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+ TEST_VERIFY (WIFSIGNALED (result.status));
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+ if (WIFSIGNALED (result.status))
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+ TEST_VERIFY (WTERMSIG (result.status) == SIGABRT);
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+ support_capture_subprocess_free (&result);
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+ success = true;
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+ }
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+ TEST_VERIFY (success);
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+}
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+
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+/* Implementation details must be kept in sync with malloc. */
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+#define TCACHE_FILL_COUNT 7
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+#define TCACHE_ALLOC_SIZE 0x20
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+#define MALLOC_CONSOLIDATE_SIZE 256*1024
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+
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+/* Try corrupting the tcache list. */
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+static void
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+test_tcache (void *closure)
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+{
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+ int mask = ((int *)closure)[0];
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+ size_t size = TCACHE_ALLOC_SIZE;
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+
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+ /* Populate the tcache list. */
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+ void * volatile a = malloc (size);
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+ void * volatile b = malloc (size);
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+ void * volatile c = malloc (size);
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+ free (a);
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+ free (b);
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+ free (c);
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+
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+ /* Corrupt the pointer with a random value, and avoid optimizations. */
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+ printf ("Before: c=%p, c[0]=%p\n", c, ((void **)c)[0]);
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+ memset (c, mask & 0xFF, size);
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+ printf ("After: c=%p, c[0]=%p\n", c, ((void **)c)[0]);
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+
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+ c = malloc (size);
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+ /* This line will trigger the Safe-Linking check. */
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+ b = malloc (size);
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+ printf ("b=%p\n", b);
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+}
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+
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+/* Try corrupting the fastbin list. */
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+static void
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+test_fastbin (void *closure)
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+{
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+ int i;
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+ int mask = ((int *)closure)[0];
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+ size_t size = TCACHE_ALLOC_SIZE;
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+
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+ /* Take the tcache out of the game. */
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+ for (i = 0; i < TCACHE_FILL_COUNT; ++i)
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+ {
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+ void * volatile p = calloc (1, size);
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+ free (p);
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+ }
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+
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+ /* Populate the fastbin list. */
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+ void * volatile a = calloc (1, size);
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+ void * volatile b = calloc (1, size);
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+ void * volatile c = calloc (1, size);
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+ free (a);
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+ free (b);
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+ free (c);
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+
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+ /* Corrupt the pointer with a random value, and avoid optimizations. */
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+ printf ("Before: c=%p, c[0]=%p\n", c, ((void **)c)[0]);
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+ memset (c, mask & 0xFF, size);
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+ printf ("After: c=%p, c[0]=%p\n", c, ((void **)c)[0]);
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+
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+ c = calloc (1, size);
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+ /* This line will trigger the Safe-Linking check. */
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+ b = calloc (1, size);
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+ printf ("b=%p\n", b);
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+}
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+
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+/* Try corrupting the fastbin list and trigger a consolidate. */
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+static void
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+test_fastbin_consolidate (void *closure)
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+{
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+ int i;
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+ int mask = ((int*)closure)[0];
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+ size_t size = TCACHE_ALLOC_SIZE;
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+
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+ /* Take the tcache out of the game. */
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+ for (i = 0; i < TCACHE_FILL_COUNT; ++i)
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+ {
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+ void * volatile p = calloc (1, size);
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+ free (p);
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+ }
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+
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+ /* Populate the fastbin list. */
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+ void * volatile a = calloc (1, size);
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+ void * volatile b = calloc (1, size);
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+ void * volatile c = calloc (1, size);
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+ free (a);
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+ free (b);
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+ free (c);
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+
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+ /* Corrupt the pointer with a random value, and avoid optimizations. */
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+ printf ("Before: c=%p, c[0]=%p\n", c, ((void **)c)[0]);
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+ memset (c, mask & 0xFF, size);
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+ printf ("After: c=%p, c[0]=%p\n", c, ((void **)c)[0]);
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+
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+ /* This line will trigger the Safe-Linking check. */
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+ b = malloc (MALLOC_CONSOLIDATE_SIZE);
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+ printf ("b=%p\n", b);
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+}
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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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+ /* Seed the random for the test. */
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+ srand (time (NULL));
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+
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+ check ("test_tcache", test_tcache,
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+ "malloc(): unaligned tcache chunk detected\n");
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+ check ("test_fastbin", test_fastbin,
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+ "malloc(): unaligned fastbin chunk detected 2\n");
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+ check ("test_fastbin_consolidate", test_fastbin_consolidate,
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+ "malloc_consolidate(): unaligned fastbin chunk detected\n");
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+
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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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