| 1 | /* Test that malloc tcache catches double free. |
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| 2 | Copyright (C) 2018-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #include <malloc.h> |
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| 20 | #include <string.h> |
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| 21 | |
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| 22 | /* Prevent GCC from optimizing away any malloc/free pairs. */ |
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| 23 | #pragma GCC optimize ("O0") |
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| 24 | |
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| 25 | static int |
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| 26 | do_test (void) |
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| 27 | { |
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| 28 | /* Do two allocation of any size that fit in tcache, and one that |
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| 29 | doesn't. */ |
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| 30 | int ** volatile a = malloc (size: 32); |
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| 31 | int ** volatile b = malloc (size: 32); |
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| 32 | /* This is just under the mmap threshold. */ |
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| 33 | int ** volatile c = malloc (size: 127 * 1024); |
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| 34 | |
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| 35 | /* The invalid "tcache bucket" we might dereference will likely end |
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| 36 | up somewhere within this memory block, so make all the accidental |
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| 37 | "next" pointers cause segfaults. BZ #23907. */ |
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| 38 | memset (c, 0xff, 127 * 1024); |
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| 39 | |
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| 40 | free (ptr: a); // puts in tcache |
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| 41 | |
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| 42 | /* A is now free and contains the key we use to detect in-tcache. |
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| 43 | Copy the key to the other chunks. */ |
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| 44 | memcpy (b, a, 32); |
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| 45 | memcpy (c, a, 32); |
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| 46 | |
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| 47 | /* This free tests the "are we in the tcache already" loop with a |
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| 48 | VALID bin but "coincidental" matching key. */ |
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| 49 | free (ptr: b); // should NOT abort |
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| 50 | /* This free tests the "is it a valid tcache bin" test. */ |
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| 51 | free (ptr: c); // should NOT abort |
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| 52 | |
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| 53 | return 0; |
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| 54 | } |
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| 55 | |
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| 56 | #include <support/test-driver.c> |
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| 57 | |
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