xref: /illumos-gate/usr/src/lib/libumem/common/malloc.c (revision 4f364e7c95ee7fd9d5bbeddc1940e92405bb0e72)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #include <unistd.h>
28 #include <errno.h>
29 #include <string.h>
30 #include <sys/sysmacros.h>
31 #include "umem_base.h"
32 #include "misc.h"
33 
34 /*
35  * malloc_data_t is an 8-byte structure which is located "before" the pointer
36  * returned from {m,c,re}alloc and memalign.  The first four bytes give
37  * information about the buffer, and the second four bytes are a status byte.
38  *
39  * See umem_impl.h for the various magic numbers used, and the size
40  * encode/decode macros.
41  *
42  * The 'size' of the buffer includes the tags.  That is, we encode the
43  * argument to umem_alloc(), not the argument to malloc().
44  */
45 
46 typedef struct malloc_data {
47 	uint32_t malloc_size;
48 	uint32_t malloc_stat; /* = UMEM_MALLOC_ENCODE(state, malloc_size) */
49 } malloc_data_t;
50 
51 /*
52  * Because we do not support ptcumem on non-x86 today, we have to create these
53  * weak aliases.
54  */
55 #ifndef _x86
56 #pragma weak malloc = umem_malloc
57 #pragma weak free = umem_malloc_free
58 #endif /* !_x86 */
59 
60 void *
umem_malloc(size_t size_arg)61 umem_malloc(size_t size_arg)
62 {
63 #ifdef _LP64
64 	uint32_t high_size = 0;
65 #endif
66 	size_t size;
67 
68 	malloc_data_t *ret;
69 	size = size_arg + sizeof (malloc_data_t);
70 
71 #ifdef _LP64
72 	if (size > UMEM_SECOND_ALIGN) {
73 		size += sizeof (malloc_data_t);
74 		high_size = (size >> 32);
75 	}
76 #endif
77 	if (size < size_arg) {
78 		errno = ENOMEM;			/* overflow */
79 		return (NULL);
80 	}
81 	ret = (malloc_data_t *)_umem_alloc(size, UMEM_DEFAULT);
82 	if (ret == NULL) {
83 		if (size <= UMEM_MAXBUF)
84 			errno = EAGAIN;
85 		else
86 			errno = ENOMEM;
87 		return (NULL);
88 #ifdef _LP64
89 	} else if (high_size > 0) {
90 		uint32_t low_size = (uint32_t)size;
91 
92 		/*
93 		 * uses different magic numbers to make it harder to
94 		 * undetectably corrupt
95 		 */
96 		ret->malloc_size = high_size;
97 		ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_MAGIC, high_size);
98 		ret++;
99 
100 		ret->malloc_size = low_size;
101 		ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_OVERSIZE_MAGIC,
102 		    low_size);
103 		ret++;
104 	} else if (size > UMEM_SECOND_ALIGN) {
105 		uint32_t low_size = (uint32_t)size;
106 
107 		ret++; /* leave the first 8 bytes alone */
108 
109 		ret->malloc_size = low_size;
110 		ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_SECOND_MAGIC,
111 		    low_size);
112 		ret++;
113 #endif
114 	} else {
115 		ret->malloc_size = size;
116 		ret->malloc_stat = UMEM_MALLOC_ENCODE(MALLOC_MAGIC, size);
117 		ret++;
118 	}
119 	return ((void *)ret);
120 }
121 
122 void *
calloc(size_t nelem,size_t elsize)123 calloc(size_t nelem, size_t elsize)
124 {
125 	size_t size = nelem * elsize;
126 	void *retval;
127 
128 	if (nelem > 0 && elsize > 0 && size/nelem != elsize) {
129 		errno = ENOMEM;				/* overflow */
130 		return (NULL);
131 	}
132 
133 	retval = malloc(size);
134 	if (retval == NULL)
135 		return (NULL);
136 
137 	(void) memset(retval, 0, size);
138 	return (retval);
139 }
140 
141 /*
142  * memalign uses vmem_xalloc to do its work.
143  *
144  * in 64-bit, the memaligned buffer always has two tags.  This simplifies the
145  * code.
146  */
147 
148 void *
memalign(size_t align,size_t size_arg)149 memalign(size_t align, size_t size_arg)
150 {
151 	size_t size;
152 	uintptr_t phase;
153 
154 	void *buf;
155 	malloc_data_t *ret;
156 
157 	size_t overhead;
158 
159 	if (size_arg == 0 || align == 0 || (align & (align - 1)) != 0) {
160 		errno = EINVAL;
161 		return (NULL);
162 	}
163 
164 	/*
165 	 * if malloc provides the required alignment, use it.
166 	 */
167 	if (align <= UMEM_ALIGN ||
168 	    (align <= UMEM_SECOND_ALIGN && size_arg >= UMEM_SECOND_ALIGN))
169 		return (malloc(size_arg));
170 
171 #ifdef _LP64
172 	overhead = 2 * sizeof (malloc_data_t);
173 #else
174 	overhead = sizeof (malloc_data_t);
175 #endif
176 
177 	ASSERT(overhead <= align);
178 
179 	size = size_arg + overhead;
180 	phase = align - overhead;
181 
182 	if (umem_memalign_arena == NULL && umem_init() == 0) {
183 		errno = ENOMEM;
184 		return (NULL);
185 	}
186 
187 	if (size < size_arg) {
188 		errno = ENOMEM;			/* overflow */
189 		return (NULL);
190 	}
191 
192 	buf = vmem_xalloc(umem_memalign_arena, size, align, phase,
193 	    0, NULL, NULL, VM_NOSLEEP);
194 
195 	if (buf == NULL) {
196 		if ((size_arg + align) <= UMEM_MAXBUF)
197 			errno = EAGAIN;
198 		else
199 			errno = ENOMEM;
200 
201 		return (NULL);
202 	}
203 
204 	ret = (malloc_data_t *)buf;
205 	{
206 		uint32_t low_size = (uint32_t)size;
207 
208 #ifdef _LP64
209 		uint32_t high_size = (uint32_t)(size >> 32);
210 
211 		ret->malloc_size = high_size;
212 		ret->malloc_stat = UMEM_MALLOC_ENCODE(MEMALIGN_MAGIC,
213 		    high_size);
214 		ret++;
215 #endif
216 
217 		ret->malloc_size = low_size;
218 		ret->malloc_stat = UMEM_MALLOC_ENCODE(MEMALIGN_MAGIC, low_size);
219 		ret++;
220 	}
221 
222 	ASSERT(P2PHASE((uintptr_t)ret, align) == 0);
223 	ASSERT((void *)((uintptr_t)ret - overhead) == buf);
224 
225 	return ((void *)ret);
226 }
227 
228 void *
valloc(size_t size)229 valloc(size_t size)
230 {
231 	return (memalign(pagesize, size));
232 }
233 
234 /*
235  * process_free:
236  *
237  * Pulls information out of a buffer pointer, and optionally free it.
238  * This is used by free() and realloc() to process buffers.
239  *
240  * On failure, calls umem_err_recoverable() with an appropriate message
241  * On success, returns the data size through *data_size_arg, if (!is_free).
242  *
243  * Preserves errno, since free()'s semantics require it.
244  */
245 
246 static int
process_free(void * buf_arg,int do_free,size_t * data_size_arg)247 process_free(void *buf_arg,
248     int do_free,		/* free the buffer, or just get its size? */
249     size_t *data_size_arg)	/* output: bytes of data in buf_arg */
250 {
251 	malloc_data_t *buf;
252 
253 	void *base;
254 	size_t size;
255 	size_t data_size;
256 
257 	const char *message;
258 	int old_errno = errno;
259 
260 	buf = (malloc_data_t *)buf_arg;
261 
262 	buf--;
263 	size = buf->malloc_size;
264 
265 	switch (UMEM_MALLOC_DECODE(buf->malloc_stat, size)) {
266 
267 	case MALLOC_MAGIC:
268 		base = (void *)buf;
269 		data_size = size - sizeof (malloc_data_t);
270 
271 		if (do_free)
272 			buf->malloc_stat = UMEM_FREE_PATTERN_32;
273 
274 		goto process_malloc;
275 
276 #ifdef _LP64
277 	case MALLOC_SECOND_MAGIC:
278 		base = (void *)(buf - 1);
279 		data_size = size - 2 * sizeof (malloc_data_t);
280 
281 		if (do_free)
282 			buf->malloc_stat = UMEM_FREE_PATTERN_32;
283 
284 		goto process_malloc;
285 
286 	case MALLOC_OVERSIZE_MAGIC: {
287 		size_t high_size;
288 
289 		buf--;
290 		high_size = buf->malloc_size;
291 
292 		if (UMEM_MALLOC_DECODE(buf->malloc_stat, high_size) !=
293 		    MALLOC_MAGIC) {
294 			message = "invalid or corrupted buffer";
295 			break;
296 		}
297 
298 		size += high_size << 32;
299 
300 		base = (void *)buf;
301 		data_size = size - 2 * sizeof (malloc_data_t);
302 
303 		if (do_free) {
304 			buf->malloc_stat = UMEM_FREE_PATTERN_32;
305 			(buf + 1)->malloc_stat = UMEM_FREE_PATTERN_32;
306 		}
307 
308 		goto process_malloc;
309 	}
310 #endif
311 
312 	case MEMALIGN_MAGIC: {
313 		size_t overhead = sizeof (malloc_data_t);
314 
315 #ifdef _LP64
316 		size_t high_size;
317 
318 		overhead += sizeof (malloc_data_t);
319 
320 		buf--;
321 		high_size = buf->malloc_size;
322 
323 		if (UMEM_MALLOC_DECODE(buf->malloc_stat, high_size) !=
324 		    MEMALIGN_MAGIC) {
325 			message = "invalid or corrupted buffer";
326 			break;
327 		}
328 		size += high_size << 32;
329 
330 		/*
331 		 * destroy the main tag's malloc_stat
332 		 */
333 		if (do_free)
334 			(buf + 1)->malloc_stat = UMEM_FREE_PATTERN_32;
335 #endif
336 
337 		base = (void *)buf;
338 		data_size = size - overhead;
339 
340 		if (do_free)
341 			buf->malloc_stat = UMEM_FREE_PATTERN_32;
342 
343 		goto process_memalign;
344 	}
345 	default:
346 		if (buf->malloc_stat == UMEM_FREE_PATTERN_32)
347 			message = "double-free or invalid buffer";
348 		else
349 			message = "invalid or corrupted buffer";
350 		break;
351 	}
352 
353 	umem_err_recoverable("%s(%p): %s\n",
354 	    do_free? "free" : "realloc", buf_arg, message);
355 
356 	errno = old_errno;
357 	return (0);
358 
359 process_malloc:
360 	if (do_free)
361 		_umem_free(base, size);
362 	else
363 		*data_size_arg = data_size;
364 
365 	errno = old_errno;
366 	return (1);
367 
368 process_memalign:
369 	if (do_free)
370 		vmem_xfree(umem_memalign_arena, base, size);
371 	else
372 		*data_size_arg = data_size;
373 
374 	errno = old_errno;
375 	return (1);
376 }
377 
378 void
umem_malloc_free(void * buf)379 umem_malloc_free(void *buf)
380 {
381 	if (buf == NULL)
382 		return;
383 
384 	/*
385 	 * Process buf, freeing it if it is not corrupt.
386 	 */
387 	(void) process_free(buf, 1, NULL);
388 }
389 
390 void *
realloc(void * buf_arg,size_t newsize)391 realloc(void *buf_arg, size_t newsize)
392 {
393 	size_t oldsize;
394 	void *buf;
395 
396 	if (buf_arg == NULL)
397 		return (malloc(newsize));
398 
399 	if (newsize == 0) {
400 		free(buf_arg);
401 		return (NULL);
402 	}
403 
404 	/*
405 	 * get the old data size without freeing the buffer
406 	 */
407 	if (process_free(buf_arg, 0, &oldsize) == 0) {
408 		errno = EINVAL;
409 		return (NULL);
410 	}
411 
412 	if (newsize == oldsize)		/* size didn't change */
413 		return (buf_arg);
414 
415 	buf = malloc(newsize);
416 	if (buf == NULL)
417 		return (NULL);
418 
419 	(void) memcpy(buf, buf_arg, MIN(newsize, oldsize));
420 	free(buf_arg);
421 	return (buf);
422 }
423