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commit 7c9a7c68363051cfc5fa1ebb96b3b2c1f82dcb76
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Author: DJ Delorie <dj@redhat.com>
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Date: Fri Nov 30 22:13:09 2018 -0500
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malloc: Add another test for tcache double free check.
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This one tests for BZ#23907 where the double free
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test didn't check the tcache bin bounds before dereferencing
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the bin.
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[BZ #23907]
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* malloc/tst-tcfree3.c: New.
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* malloc/Makefile: Add it.
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diff --git a/malloc/Makefile b/malloc/Makefile
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index e6dfbfc14cb3d140..388cf7e9ee3a2569 100644
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--- a/malloc/Makefile
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+++ b/malloc/Makefile
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@@ -38,7 +38,7 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
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tst-malloc_info \
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tst-malloc-too-large \
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tst-malloc-stats-cancellation \
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- tst-tcfree1 tst-tcfree2 \
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+ tst-tcfree1 tst-tcfree2 tst-tcfree3 \
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tests-static := \
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tst-interpose-static-nothread \
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diff --git a/malloc/tst-tcfree3.c b/malloc/tst-tcfree3.c
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new file mode 100644
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index 0000000000000000..016d30ddd8114082
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--- /dev/null
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+++ b/malloc/tst-tcfree3.c
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@@ -0,0 +1,56 @@
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+/* Test that malloc tcache catches double free.
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+ Copyright (C) 2018 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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+ <http://www.gnu.org/licenses/>. */
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+
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+#include <malloc.h>
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+#include <string.h>
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+
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+/* Prevent GCC from optimizing away any malloc/free pairs. */
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+#pragma GCC optimize ("O0")
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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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+ /* Do two allocation of any size that fit in tcache, and one that
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+ doesn't. */
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+ int ** volatile a = malloc (32);
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+ int ** volatile b = malloc (32);
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+ /* This is just under the mmap threshold. */
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+ int ** volatile c = malloc (127 * 1024);
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+
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+ /* The invalid "tcache bucket" we might dereference will likely end
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+ up somewhere within this memory block, so make all the accidental
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+ "next" pointers cause segfaults. BZ #23907. */
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+ memset (c, 0xff, 127 * 1024);
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+
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+ free (a); // puts in tcache
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+
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+ /* A is now free and contains the key we use to detect in-tcache.
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+ Copy the key to the other chunks. */
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+ memcpy (b, a, 32);
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+ memcpy (c, a, 32);
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+
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+ /* This free tests the "are we in the tcache already" loop with a
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+ VALID bin but "coincidental" matching key. */
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+ free (b); // should NOT abort
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+ /* This free tests the "is it a valid tcache bin" test. */
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+ free (c); // should NOT abort
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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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