1/* Test and verify that too-large memory allocations fail with ENOMEM.
2 Copyright (C) 2018-2024 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19/* Bug 22375 reported a regression in malloc where if after malloc'ing then
20 free'ing a small block of memory, malloc is then called with a really
21 large size argument (close to SIZE_MAX): instead of returning NULL and
22 setting errno to ENOMEM, malloc incorrectly returns the previously
23 allocated block instead. Bug 22343 reported a similar case where
24 posix_memalign incorrectly returns successfully when called with an with
25 a really large size argument.
26
27 Both of these were caused by integer overflows in the allocator when it
28 was trying to pad the requested size to allow for book-keeping or
29 alignment. This test guards against such bugs by repeatedly allocating
30 and freeing small blocks of memory then trying to allocate various block
31 sizes larger than the memory bus width of 64-bit targets, or almost
32 as large as SIZE_MAX on 32-bit targets supported by glibc. In each case,
33 it verifies that such impossibly large allocations correctly fail. */
34
35
36#include <stdlib.h>
37#include <malloc.h>
38#include <errno.h>
39#include <stdint.h>
40#include <sys/resource.h>
41#include <libc-diag.h>
42#include <support/check.h>
43#include <unistd.h>
44#include <sys/param.h>
45
46#include "tst-malloc-aux.h"
47
48/* This function prepares for each 'too-large memory allocation' test by
49 performing a small successful malloc/free and resetting errno prior to
50 the actual test. */
51static void
52test_setup (void)
53{
54 void *volatile ptr = malloc (16);
55 TEST_VERIFY_EXIT (ptr != NULL);
56 free (ptr: ptr);
57 errno = 0;
58}
59
60
61/* This function tests each of:
62 - malloc (SIZE)
63 - realloc (PTR_FOR_REALLOC, SIZE)
64 - for various values of NMEMB:
65 - calloc (NMEMB, SIZE/NMEMB)
66 - calloc (SIZE/NMEMB, NMEMB)
67 - reallocarray (PTR_FOR_REALLOC, NMEMB, SIZE/NMEMB)
68 - reallocarray (PTR_FOR_REALLOC, SIZE/NMEMB, NMEMB)
69 and precedes each of these tests with a small malloc/free before it. */
70static void
71test_large_allocations (size_t size)
72{
73 void * ptr_to_realloc;
74
75 test_setup ();
76 DIAG_PUSH_NEEDS_COMMENT;
77#if __GNUC_PREREQ (7, 0)
78 /* GCC 7 warns about too-large allocations; here we want to test
79 that they fail. */
80 DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
81#endif
82 TEST_VERIFY (malloc (size) == NULL);
83#if __GNUC_PREREQ (7, 0)
84 DIAG_POP_NEEDS_COMMENT;
85#endif
86 TEST_VERIFY (errno == ENOMEM);
87
88 ptr_to_realloc = malloc (16);
89 TEST_VERIFY_EXIT (ptr_to_realloc != NULL);
90 test_setup ();
91#if __GNUC_PREREQ (7, 0)
92 DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
93#endif
94 TEST_VERIFY (realloc (ptr_to_realloc, size) == NULL);
95#if __GNUC_PREREQ (7, 0)
96 DIAG_POP_NEEDS_COMMENT;
97#endif
98 TEST_VERIFY (errno == ENOMEM);
99#if __GNUC_PREREQ (12, 0)
100 /* Ignore a warning about using a pointer made indeterminate by
101 a prior call to realloc(). */
102 DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
103#endif
104 free (ptr: ptr_to_realloc);
105#if __GNUC_PREREQ (12, 0)
106 DIAG_POP_NEEDS_COMMENT;
107#endif
108
109 for (size_t nmemb = 1; nmemb <= 8; nmemb *= 2)
110 if ((size % nmemb) == 0)
111 {
112 test_setup ();
113 TEST_VERIFY (calloc (nmemb, size / nmemb) == NULL);
114 TEST_VERIFY (errno == ENOMEM);
115
116 test_setup ();
117 TEST_VERIFY (calloc (size / nmemb, nmemb) == NULL);
118 TEST_VERIFY (errno == ENOMEM);
119
120 ptr_to_realloc = malloc (16);
121 TEST_VERIFY_EXIT (ptr_to_realloc != NULL);
122 test_setup ();
123 TEST_VERIFY (reallocarray (ptr_to_realloc, nmemb, size / nmemb) == NULL);
124 TEST_VERIFY (errno == ENOMEM);
125#if __GNUC_PREREQ (12, 0)
126 /* Ignore a warning about using a pointer made indeterminate by
127 a prior call to realloc(). */
128 DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
129#endif
130 free (ptr: ptr_to_realloc);
131#if __GNUC_PREREQ (12, 0)
132 DIAG_POP_NEEDS_COMMENT;
133#endif
134
135 ptr_to_realloc = malloc (16);
136 TEST_VERIFY_EXIT (ptr_to_realloc != NULL);
137 test_setup ();
138 TEST_VERIFY (reallocarray (ptr_to_realloc, size / nmemb, nmemb) == NULL);
139 TEST_VERIFY (errno == ENOMEM);
140#if __GNUC_PREREQ (12, 0)
141 /* Ignore a warning about using a pointer made indeterminate by
142 a prior call to realloc(). */
143 DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
144#endif
145 free (ptr: ptr_to_realloc);
146#if __GNUC_PREREQ (12, 0)
147 DIAG_POP_NEEDS_COMMENT;
148#endif
149 }
150 else
151 break;
152}
153
154
155static long pagesize;
156
157/* This function tests the following aligned memory allocation functions
158 using several valid alignments and precedes each allocation test with a
159 small malloc/free before it:
160 memalign, posix_memalign, aligned_alloc, valloc, pvalloc. */
161static void
162test_large_aligned_allocations (size_t size)
163{
164 /* ptr stores the result of posix_memalign but since all those calls
165 should fail, posix_memalign should never change ptr. We set it to
166 NULL here and later on we check that it remains NULL after each
167 posix_memalign call. */
168 void * ptr = NULL;
169
170 size_t align;
171
172 /* All aligned memory allocation functions expect an alignment that is a
173 power of 2. Given this, we test each of them with every valid
174 alignment from 1 thru PAGESIZE. */
175 for (align = 1; align <= pagesize; align *= 2)
176 {
177 test_setup ();
178#if __GNUC_PREREQ (7, 0)
179 DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
180#endif
181 TEST_VERIFY (memalign (align, size) == NULL);
182#if __GNUC_PREREQ (7, 0)
183 DIAG_POP_NEEDS_COMMENT;
184#endif
185 TEST_VERIFY (errno == ENOMEM);
186
187 /* posix_memalign expects an alignment that is a power of 2 *and* a
188 multiple of sizeof (void *). */
189 if ((align % sizeof (void *)) == 0)
190 {
191 test_setup ();
192 TEST_VERIFY (posix_memalign (&ptr, align, size) == ENOMEM);
193 TEST_VERIFY (ptr == NULL);
194 }
195
196 /* aligned_alloc expects a size that is a multiple of alignment. */
197 if ((size % align) == 0)
198 {
199 test_setup ();
200#if __GNUC_PREREQ (7, 0)
201 DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
202#endif
203 TEST_VERIFY (aligned_alloc (align, size) == NULL);
204#if __GNUC_PREREQ (7, 0)
205 DIAG_POP_NEEDS_COMMENT;
206#endif
207 TEST_VERIFY (errno == ENOMEM);
208 }
209 }
210
211 /* Both valloc and pvalloc return page-aligned memory. */
212
213 test_setup ();
214#if __GNUC_PREREQ (7, 0)
215 DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
216#endif
217 TEST_VERIFY (valloc (size) == NULL);
218#if __GNUC_PREREQ (7, 0)
219 DIAG_POP_NEEDS_COMMENT;
220#endif
221 TEST_VERIFY (errno == ENOMEM);
222
223 test_setup ();
224#if __GNUC_PREREQ (7, 0)
225 DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
226#endif
227 TEST_VERIFY (pvalloc (size) == NULL);
228#if __GNUC_PREREQ (7, 0)
229 DIAG_POP_NEEDS_COMMENT;
230#endif
231 TEST_VERIFY (errno == ENOMEM);
232}
233
234
235#define FOURTEEN_ON_BITS ((1UL << 14) - 1)
236#define FIFTY_ON_BITS ((1UL << 50) - 1)
237
238
239static int
240do_test (void)
241{
242
243#if __WORDSIZE >= 64
244
245 /* This test assumes that none of the supported targets have an address
246 bus wider than 50 bits, and that therefore allocations for sizes wider
247 than 50 bits will fail. Here, we ensure that the assumption continues
248 to be true in the future when we might have address buses wider than 50
249 bits. */
250
251 struct rlimit alloc_size_limit
252 = {
253 .rlim_cur = FIFTY_ON_BITS,
254 .rlim_max = FIFTY_ON_BITS
255 };
256
257 setrlimit (RLIMIT_AS, rlimits: &alloc_size_limit);
258
259#endif /* __WORDSIZE >= 64 */
260
261 DIAG_PUSH_NEEDS_COMMENT;
262#if __GNUC_PREREQ (7, 0)
263 /* GCC 7 warns about too-large allocations; here we want to test
264 that they fail. */
265 DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
266#endif
267
268 /* Aligned memory allocation functions need to be tested up to alignment
269 size equivalent to page size, which should be a power of 2. */
270 pagesize = sysconf (_SC_PAGESIZE);
271 TEST_VERIFY_EXIT (powerof2 (pagesize));
272
273 /* Loop 1: Ensure that all allocations with SIZE close to SIZE_MAX, i.e.
274 in the range (SIZE_MAX - 2^14, SIZE_MAX], fail.
275
276 We can expect that this range of allocation sizes will always lead to
277 an allocation failure on both 64 and 32 bit targets, because:
278
279 1. no currently supported 64-bit target has an address bus wider than
280 50 bits -- and (2^64 - 2^14) is much wider than that;
281
282 2. on 32-bit targets, even though 2^32 is only 4 GB and potentially
283 addressable, glibc itself is more than 2^14 bytes in size, and
284 therefore once glibc is loaded, less than (2^32 - 2^14) bytes remain
285 available. */
286
287 for (size_t i = 0; i <= FOURTEEN_ON_BITS; i++)
288 {
289 test_large_allocations (SIZE_MAX - i);
290 test_large_aligned_allocations (SIZE_MAX - i);
291 }
292
293 /* Allocation larger than PTRDIFF_MAX does play well with C standard,
294 since pointer subtraction within the object might overflow ptrdiff_t
295 resulting in undefined behavior. To prevent it malloc function fail
296 for such allocations. */
297 for (size_t i = 1; i <= FOURTEEN_ON_BITS; i++)
298 {
299 test_large_allocations (PTRDIFF_MAX + i);
300 test_large_aligned_allocations (PTRDIFF_MAX + i);
301 }
302
303#if __WORDSIZE >= 64
304 /* On 64-bit targets, we need to test a much wider range of too-large
305 sizes, so we test at intervals of (1 << 50) that allocation sizes
306 ranging from SIZE_MAX down to (1 << 50) fail:
307 The 14 MSBs are decremented starting from "all ON" going down to 1,
308 the 50 LSBs are "all ON" and then "all OFF" during every iteration. */
309 for (size_t msbs = FOURTEEN_ON_BITS; msbs >= 1; msbs--)
310 {
311 size_t size = (msbs << 50) | FIFTY_ON_BITS;
312 test_large_allocations (size);
313 test_large_aligned_allocations (size);
314
315 size = msbs << 50;
316 test_large_allocations (size);
317 test_large_aligned_allocations (size);
318 }
319#endif /* __WORDSIZE >= 64 */
320
321 DIAG_POP_NEEDS_COMMENT;
322
323 return 0;
324}
325
326
327#include <support/test-driver.c>
328

source code of glibc/malloc/tst-malloc-too-large.c