lib/test_kasan.c

   1 /*
   2  *
   3  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
   4  * Author: Andrey Ryabinin <a.ryabinin@samsung.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #define pr_fmt(fmt) "kasan test: %s " fmt, __func__
  13
  14 #include <linux/delay.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mman.h>
  17 #include <linux/mm.h>
  18 #include <linux/printk.h>
  19 #include <linux/slab.h>
  20 #include <linux/string.h>
  21 #include <linux/uaccess.h>
  22 #include <linux/module.h>
  23 #include <linux/kasan.h>
  24
  25 /*
  26  * Note: test functions are marked noinline so that their names appear in
  27  * reports.
  28  */
  29
  30 static noinline void __init kmalloc_oob_right(void)
  31 {
  32         char *ptr;
  33         size_t size = 123;
  34
  35         pr_info("out-of-bounds to right\n");
  36         ptr = kmalloc(size, GFP_KERNEL);
  37         if (!ptr) {
  38                 pr_err("Allocation failed\n");
  39                 return;
  40         }
  41
  42         ptr[size] = 'x';
  43         kfree(ptr);
  44 }
  45
  46 static noinline void __init kmalloc_oob_left(void)
  47 {
  48         char *ptr;
  49         size_t size = 15;
  50
  51         pr_info("out-of-bounds to left\n");
  52         ptr = kmalloc(size, GFP_KERNEL);
  53         if (!ptr) {
  54                 pr_err("Allocation failed\n");
  55                 return;
  56         }
  57
  58         *ptr = *(ptr - 1);
  59         kfree(ptr);
  60 }
  61
  62 static noinline void __init kmalloc_node_oob_right(void)
  63 {
  64         char *ptr;
  65         size_t size = 4096;
  66
  67         pr_info("kmalloc_node(): out-of-bounds to right\n");
  68         ptr = kmalloc_node(size, GFP_KERNEL, 0);
  69         if (!ptr) {
  70                 pr_err("Allocation failed\n");
  71                 return;
  72         }
  73
  74         ptr[size] = 0;
  75         kfree(ptr);
  76 }
  77
  78 #ifdef CONFIG_SLUB
  79 static noinline void __init kmalloc_pagealloc_oob_right(void)
  80 {
  81         char *ptr;
  82         size_t size = KMALLOC_MAX_CACHE_SIZE + 10;
  83
  84         /* Allocate a chunk that does not fit into a SLUB cache to trigger
  85          * the page allocator fallback.
  86          */
  87         pr_info("kmalloc pagealloc allocation: out-of-bounds to right\n");
  88         ptr = kmalloc(size, GFP_KERNEL);
  89         if (!ptr) {
  90                 pr_err("Allocation failed\n");
  91                 return;
  92         }
  93
  94         ptr[size] = 0;
  95         kfree(ptr);
  96 }
  97 #endif
  98
  99 static noinline void __init kmalloc_large_oob_right(void)
 100 {
 101         char *ptr;
 102         size_t size = KMALLOC_MAX_CACHE_SIZE - 256;
 103         /* Allocate a chunk that is large enough, but still fits into a slab
 104          * and does not trigger the page allocator fallback in SLUB.
 105          */
 106         pr_info("kmalloc large allocation: out-of-bounds to right\n");
 107         ptr = kmalloc(size, GFP_KERNEL);
 108         if (!ptr) {
 109                 pr_err("Allocation failed\n");
 110                 return;
 111         }
 112
 113         ptr[size] = 0;
 114         kfree(ptr);
 115 }
 116
 117 static noinline void __init kmalloc_oob_krealloc_more(void)
 118 {
 119         char *ptr1, *ptr2;
 120         size_t size1 = 17;
 121         size_t size2 = 19;
 122
 123         pr_info("out-of-bounds after krealloc more\n");
 124         ptr1 = kmalloc(size1, GFP_KERNEL);
 125         ptr2 = krealloc(ptr1, size2, GFP_KERNEL);
 126         if (!ptr1 || !ptr2) {
 127                 pr_err("Allocation failed\n");
 128                 kfree(ptr1);
 129                 return;
 130         }
 131
 132         ptr2[size2] = 'x';
 133         kfree(ptr2);
 134 }
 135
 136 static noinline void __init kmalloc_oob_krealloc_less(void)
 137 {
 138         char *ptr1, *ptr2;
 139         size_t size1 = 17;
 140         size_t size2 = 15;
 141
 142         pr_info("out-of-bounds after krealloc less\n");
 143         ptr1 = kmalloc(size1, GFP_KERNEL);
 144         ptr2 = krealloc(ptr1, size2, GFP_KERNEL);
 145         if (!ptr1 || !ptr2) {
 146                 pr_err("Allocation failed\n");
 147                 kfree(ptr1);
 148                 return;
 149         }
 150         ptr2[size2] = 'x';
 151         kfree(ptr2);
 152 }
 153
 154 static noinline void __init kmalloc_oob_16(void)
 155 {
 156         struct {
 157                 u64 words[2];
 158         } *ptr1, *ptr2;
 159
 160         pr_info("kmalloc out-of-bounds for 16-bytes access\n");
 161         ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL);
 162         ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL);
 163         if (!ptr1 || !ptr2) {
 164                 pr_err("Allocation failed\n");
 165                 kfree(ptr1);
 166                 kfree(ptr2);
 167                 return;
 168         }
 169         *ptr1 = *ptr2;
 170         kfree(ptr1);
 171         kfree(ptr2);
 172 }
 173
 174 static noinline void __init kmalloc_oob_memset_2(void)
 175 {
 176         char *ptr;
 177         size_t size = 8;
 178
 179         pr_info("out-of-bounds in memset2\n");
 180         ptr = kmalloc(size, GFP_KERNEL);
 181         if (!ptr) {
 182                 pr_err("Allocation failed\n");
 183                 return;
 184         }
 185
 186         memset(ptr+7, 0, 2);
 187         kfree(ptr);
 188 }
 189
 190 static noinline void __init kmalloc_oob_memset_4(void)
 191 {
 192         char *ptr;
 193         size_t size = 8;
 194
 195         pr_info("out-of-bounds in memset4\n");
 196         ptr = kmalloc(size, GFP_KERNEL);
 197         if (!ptr) {
 198                 pr_err("Allocation failed\n");
 199                 return;
 200         }
 201
 202         memset(ptr+5, 0, 4);
 203         kfree(ptr);
 204 }
 205
 206
 207 static noinline void __init kmalloc_oob_memset_8(void)
 208 {
 209         char *ptr;
 210         size_t size = 8;
 211
 212         pr_info("out-of-bounds in memset8\n");
 213         ptr = kmalloc(size, GFP_KERNEL);
 214         if (!ptr) {
 215                 pr_err("Allocation failed\n");
 216                 return;
 217         }
 218
 219         memset(ptr+1, 0, 8);
 220         kfree(ptr);
 221 }
 222
 223 static noinline void __init kmalloc_oob_memset_16(void)
 224 {
 225         char *ptr;
 226         size_t size = 16;
 227
 228         pr_info("out-of-bounds in memset16\n");
 229         ptr = kmalloc(size, GFP_KERNEL);
 230         if (!ptr) {
 231                 pr_err("Allocation failed\n");
 232                 return;
 233         }
 234
 235         memset(ptr+1, 0, 16);
 236         kfree(ptr);
 237 }
 238
 239 static noinline void __init kmalloc_oob_in_memset(void)
 240 {
 241         char *ptr;
 242         size_t size = 666;
 243
 244         pr_info("out-of-bounds in memset\n");
 245         ptr = kmalloc(size, GFP_KERNEL);
 246         if (!ptr) {
 247                 pr_err("Allocation failed\n");
 248                 return;
 249         }
 250
 251         memset(ptr, 0, size+5);
 252         kfree(ptr);
 253 }
 254
 255 static noinline void __init kmalloc_uaf(void)
 256 {
 257         char *ptr;
 258         size_t size = 10;
 259
 260         pr_info("use-after-free\n");
 261         ptr = kmalloc(size, GFP_KERNEL);
 262         if (!ptr) {
 263                 pr_err("Allocation failed\n");
 264                 return;
 265         }
 266
 267         kfree(ptr);
 268         *(ptr + 8) = 'x';
 269 }
 270
 271 static noinline void __init kmalloc_uaf_memset(void)
 272 {
 273         char *ptr;
 274         size_t size = 33;
 275
 276         pr_info("use-after-free in memset\n");
 277         ptr = kmalloc(size, GFP_KERNEL);
 278         if (!ptr) {
 279                 pr_err("Allocation failed\n");
 280                 return;
 281         }
 282
 283         kfree(ptr);
 284         memset(ptr, 0, size);
 285 }
 286
 287 static noinline void __init kmalloc_uaf2(void)
 288 {
 289         char *ptr1, *ptr2;
 290         size_t size = 43;
 291
 292         pr_info("use-after-free after another kmalloc\n");
 293         ptr1 = kmalloc(size, GFP_KERNEL);
 294         if (!ptr1) {
 295                 pr_err("Allocation failed\n");
 296                 return;
 297         }
 298
 299         kfree(ptr1);
 300         ptr2 = kmalloc(size, GFP_KERNEL);
 301         if (!ptr2) {
 302                 pr_err("Allocation failed\n");
 303                 return;
 304         }
 305
 306         ptr1[40] = 'x';
 307         if (ptr1 == ptr2)
 308                 pr_err("Could not detect use-after-free: ptr1 == ptr2\n");
 309         kfree(ptr2);
 310 }
 311
 312 static noinline void __init kmem_cache_oob(void)
 313 {
 314         char *p;
 315         size_t size = 200;
 316         struct kmem_cache *cache = kmem_cache_create("test_cache",
 317                                                 size, 0,
 318                                                 0, NULL);
 319         if (!cache) {
 320                 pr_err("Cache allocation failed\n");
 321                 return;
 322         }
 323         pr_info("out-of-bounds in kmem_cache_alloc\n");
 324         p = kmem_cache_alloc(cache, GFP_KERNEL);
 325         if (!p) {
 326                 pr_err("Allocation failed\n");
 327                 kmem_cache_destroy(cache);
 328                 return;
 329         }
 330
 331         *p = p[size];
 332         kmem_cache_free(cache, p);
 333         kmem_cache_destroy(cache);
 334 }
 335
 336 static noinline void __init memcg_accounted_kmem_cache(void)
 337 {
 338         int i;
 339         char *p;
 340         size_t size = 200;
 341         struct kmem_cache *cache;
 342
 343         cache = kmem_cache_create("test_cache", size, 0, SLAB_ACCOUNT, NULL);
 344         if (!cache) {
 345                 pr_err("Cache allocation failed\n");
 346                 return;
 347         }
 348
 349         pr_info("allocate memcg accounted object\n");
 350         /*
 351          * Several allocations with a delay to allow for lazy per memcg kmem
 352          * cache creation.
 353          */
 354         for (i = 0; i < 5; i++) {
 355                 p = kmem_cache_alloc(cache, GFP_KERNEL);
 356                 if (!p)
 357                         goto free_cache;
 358
 359                 kmem_cache_free(cache, p);
 360                 msleep(100);
 361         }
 362
 363 free_cache:
 364         kmem_cache_destroy(cache);
 365 }
 366
 367 static char global_array[10];
 368
 369 static noinline void __init kasan_global_oob(void)
 370 {
 371         volatile int i = 3;
 372         char *p = &global_array[ARRAY_SIZE(global_array) + i];
 373
 374         pr_info("out-of-bounds global variable\n");
 375         *(volatile char *)p;
 376 }
 377
 378 static noinline void __init kasan_stack_oob(void)
 379 {
 380         char stack_array[10];
 381         volatile int i = 0;
 382         char *p = &stack_array[ARRAY_SIZE(stack_array) + i];
 383
 384         pr_info("out-of-bounds on stack\n");
 385         *(volatile char *)p;
 386 }
 387
 388 static noinline void __init ksize_unpoisons_memory(void)
 389 {
 390         char *ptr;
 391         size_t size = 123, real_size = size;
 392
 393         pr_info("ksize() unpoisons the whole allocated chunk\n");
 394         ptr = kmalloc(size, GFP_KERNEL);
 395         if (!ptr) {
 396                 pr_err("Allocation failed\n");
 397                 return;
 398         }
 399         real_size = ksize(ptr);
 400         /* This access doesn't trigger an error. */
 401         ptr[size] = 'x';
 402         /* This one does. */
 403         ptr[real_size] = 'y';
 404         kfree(ptr);
 405 }
 406
 407 static noinline void __init copy_user_test(void)
 408 {
 409         char *kmem;
 410         char __user *usermem;
 411         size_t size = 10;
 412         int unused;
 413
 414         kmem = kmalloc(size, GFP_KERNEL);
 415         if (!kmem)
 416                 return;
 417
 418         usermem = (char __user *)vm_mmap(NULL, 0, PAGE_SIZE,
 419                             PROT_READ | PROT_WRITE | PROT_EXEC,
 420                             MAP_ANONYMOUS | MAP_PRIVATE, 0);
 421         if (IS_ERR(usermem)) {
 422                 pr_err("Failed to allocate user memory\n");
 423                 kfree(kmem);
 424                 return;
 425         }
 426
 427         pr_info("out-of-bounds in copy_from_user()\n");
 428         unused = copy_from_user(kmem, usermem, size + 1);
 429
 430         pr_info("out-of-bounds in copy_to_user()\n");
 431         unused = copy_to_user(usermem, kmem, size + 1);
 432
 433         pr_info("out-of-bounds in __copy_from_user()\n");
 434         unused = __copy_from_user(kmem, usermem, size + 1);
 435
 436         pr_info("out-of-bounds in __copy_to_user()\n");
 437         unused = __copy_to_user(usermem, kmem, size + 1);
 438
 439         pr_info("out-of-bounds in __copy_from_user_inatomic()\n");
 440         unused = __copy_from_user_inatomic(kmem, usermem, size + 1);
 441
 442         pr_info("out-of-bounds in __copy_to_user_inatomic()\n");
 443         unused = __copy_to_user_inatomic(usermem, kmem, size + 1);
 444
 445         pr_info("out-of-bounds in strncpy_from_user()\n");
 446         unused = strncpy_from_user(kmem, usermem, size + 1);
 447
 448         vm_munmap((unsigned long)usermem, PAGE_SIZE);
 449         kfree(kmem);
 450 }
 451
 452 static noinline void __init use_after_scope_test(void)
 453 {
 454         volatile char *volatile p;
 455
 456         pr_info("use-after-scope on int\n");
 457         {
 458                 int local = 0;
 459
 460                 p = (char *)&local;
 461         }
 462         p[0] = 1;
 463         p[3] = 1;
 464
 465         pr_info("use-after-scope on array\n");
 466         {
 467                 char local[1024] = {0};
 468
 469                 p = local;
 470         }
 471         p[0] = 1;
 472         p[1023] = 1;
 473 }
 474
 475 static int __init kmalloc_tests_init(void)
 476 {
 477         /*
 478          * Temporarily enable multi-shot mode. Otherwise, we'd only get a
 479          * report for the first case.
 480          */
 481         bool multishot = kasan_save_enable_multi_shot();
 482
 483         kmalloc_oob_right();
 484         kmalloc_oob_left();
 485         kmalloc_node_oob_right();
 486 #ifdef CONFIG_SLUB
 487         kmalloc_pagealloc_oob_right();
 488 #endif
 489         kmalloc_large_oob_right();
 490         kmalloc_oob_krealloc_more();
 491         kmalloc_oob_krealloc_less();
 492         kmalloc_oob_16();
 493         kmalloc_oob_in_memset();
 494         kmalloc_oob_memset_2();
 495         kmalloc_oob_memset_4();
 496         kmalloc_oob_memset_8();
 497         kmalloc_oob_memset_16();
 498         kmalloc_uaf();
 499         kmalloc_uaf_memset();
 500         kmalloc_uaf2();
 501         kmem_cache_oob();
 502         memcg_accounted_kmem_cache();
 503         kasan_stack_oob();
 504         kasan_global_oob();
 505         ksize_unpoisons_memory();
 506         copy_user_test();
 507         use_after_scope_test();
 508
 509         kasan_restore_multi_shot(multishot);
 510
 511         return -EAGAIN;
 512 }
 513
 514 module_init(kmalloc_tests_init);
 515 MODULE_LICENSE("GPL");