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