1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * This file contains generic KASAN specific error reporting code. 4 * 5 * Copyright (c) 2014 Samsung Electronics Co., Ltd. 6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> 7 * 8 * Some code borrowed from https://github.com/xairy/kasan-prototype by 9 * Andrey Konovalov <andreyknvl@gmail.com> 10 */ 11 12 #include <linux/bitops.h> 13 #include <linux/ftrace.h> 14 #include <linux/init.h> 15 #include <linux/kernel.h> 16 #include <linux/mm.h> 17 #include <linux/printk.h> 18 #include <linux/sched.h> 19 #include <linux/sched/task_stack.h> 20 #include <linux/slab.h> 21 #include <linux/stackdepot.h> 22 #include <linux/stacktrace.h> 23 #include <linux/string.h> 24 #include <linux/types.h> 25 #include <linux/kasan.h> 26 #include <linux/module.h> 27 28 #include <asm/sections.h> 29 30 #include "kasan.h" 31 #include "../slab.h" 32 33 void *kasan_find_first_bad_addr(void *addr, size_t size) 34 { 35 void *p = addr; 36 37 if (!addr_has_metadata(p)) 38 return p; 39 40 while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p))) 41 p += KASAN_GRANULE_SIZE; 42 43 return p; 44 } 45 46 static const char *get_shadow_bug_type(struct kasan_report_info *info) 47 { 48 const char *bug_type = "unknown-crash"; 49 u8 *shadow_addr; 50 51 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr); 52 53 /* 54 * If shadow byte value is in [0, KASAN_GRANULE_SIZE) we can look 55 * at the next shadow byte to determine the type of the bad access. 56 */ 57 if (*shadow_addr > 0 && *shadow_addr <= KASAN_GRANULE_SIZE - 1) 58 shadow_addr++; 59 60 switch (*shadow_addr) { 61 case 0 ... KASAN_GRANULE_SIZE - 1: 62 /* 63 * In theory it's still possible to see these shadow values 64 * due to a data race in the kernel code. 65 */ 66 bug_type = "out-of-bounds"; 67 break; 68 case KASAN_PAGE_REDZONE: 69 case KASAN_SLAB_REDZONE: 70 bug_type = "slab-out-of-bounds"; 71 break; 72 case KASAN_GLOBAL_REDZONE: 73 bug_type = "global-out-of-bounds"; 74 break; 75 case KASAN_STACK_LEFT: 76 case KASAN_STACK_MID: 77 case KASAN_STACK_RIGHT: 78 case KASAN_STACK_PARTIAL: 79 bug_type = "stack-out-of-bounds"; 80 break; 81 case KASAN_PAGE_FREE: 82 case KASAN_SLAB_FREE: 83 case KASAN_SLAB_FREETRACK: 84 bug_type = "use-after-free"; 85 break; 86 case KASAN_ALLOCA_LEFT: 87 case KASAN_ALLOCA_RIGHT: 88 bug_type = "alloca-out-of-bounds"; 89 break; 90 case KASAN_VMALLOC_INVALID: 91 bug_type = "vmalloc-out-of-bounds"; 92 break; 93 } 94 95 return bug_type; 96 } 97 98 static const char *get_wild_bug_type(struct kasan_report_info *info) 99 { 100 const char *bug_type = "unknown-crash"; 101 102 if ((unsigned long)info->access_addr < PAGE_SIZE) 103 bug_type = "null-ptr-deref"; 104 else if ((unsigned long)info->access_addr < TASK_SIZE) 105 bug_type = "user-memory-access"; 106 else 107 bug_type = "wild-memory-access"; 108 109 return bug_type; 110 } 111 112 static const char *get_bug_type(struct kasan_report_info *info) 113 { 114 /* 115 * If access_size is a negative number, then it has reason to be 116 * defined as out-of-bounds bug type. 117 * 118 * Casting negative numbers to size_t would indeed turn up as 119 * a large size_t and its value will be larger than ULONG_MAX/2, 120 * so that this can qualify as out-of-bounds. 121 */ 122 if (info->access_addr + info->access_size < info->access_addr) 123 return "out-of-bounds"; 124 125 if (addr_has_metadata(info->access_addr)) 126 return get_shadow_bug_type(info); 127 return get_wild_bug_type(info); 128 } 129 130 void kasan_complete_mode_report_info(struct kasan_report_info *info) 131 { 132 struct kasan_alloc_meta *alloc_meta; 133 struct kasan_free_meta *free_meta; 134 135 if (!info->bug_type) 136 info->bug_type = get_bug_type(info); 137 138 if (!info->cache || !info->object) 139 return; 140 141 alloc_meta = kasan_get_alloc_meta(info->cache, info->object); 142 if (alloc_meta) 143 memcpy(&info->alloc_track, &alloc_meta->alloc_track, 144 sizeof(info->alloc_track)); 145 146 if (*(u8 *)kasan_mem_to_shadow(info->object) == KASAN_SLAB_FREETRACK) { 147 /* Free meta must be present with KASAN_SLAB_FREETRACK. */ 148 free_meta = kasan_get_free_meta(info->cache, info->object); 149 memcpy(&info->free_track, &free_meta->free_track, 150 sizeof(info->free_track)); 151 } 152 } 153 154 void kasan_metadata_fetch_row(char *buffer, void *row) 155 { 156 memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW); 157 } 158 159 void kasan_print_aux_stacks(struct kmem_cache *cache, const void *object) 160 { 161 struct kasan_alloc_meta *alloc_meta; 162 163 alloc_meta = kasan_get_alloc_meta(cache, object); 164 if (!alloc_meta) 165 return; 166 167 if (alloc_meta->aux_stack[0]) { 168 pr_err("Last potentially related work creation:\n"); 169 stack_depot_print(alloc_meta->aux_stack[0]); 170 pr_err("\n"); 171 } 172 if (alloc_meta->aux_stack[1]) { 173 pr_err("Second to last potentially related work creation:\n"); 174 stack_depot_print(alloc_meta->aux_stack[1]); 175 pr_err("\n"); 176 } 177 } 178 179 #ifdef CONFIG_KASAN_STACK 180 static bool __must_check tokenize_frame_descr(const char **frame_descr, 181 char *token, size_t max_tok_len, 182 unsigned long *value) 183 { 184 const char *sep = strchr(*frame_descr, ' '); 185 186 if (sep == NULL) 187 sep = *frame_descr + strlen(*frame_descr); 188 189 if (token != NULL) { 190 const size_t tok_len = sep - *frame_descr; 191 192 if (tok_len + 1 > max_tok_len) { 193 pr_err("KASAN internal error: frame description too long: %s\n", 194 *frame_descr); 195 return false; 196 } 197 198 /* Copy token (+ 1 byte for '\0'). */ 199 strscpy(token, *frame_descr, tok_len + 1); 200 } 201 202 /* Advance frame_descr past separator. */ 203 *frame_descr = sep + 1; 204 205 if (value != NULL && kstrtoul(token, 10, value)) { 206 pr_err("KASAN internal error: not a valid number: %s\n", token); 207 return false; 208 } 209 210 return true; 211 } 212 213 static void print_decoded_frame_descr(const char *frame_descr) 214 { 215 /* 216 * We need to parse the following string: 217 * "n alloc_1 alloc_2 ... alloc_n" 218 * where alloc_i looks like 219 * "offset size len name" 220 * or "offset size len name:line". 221 */ 222 223 char token[64]; 224 unsigned long num_objects; 225 226 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), 227 &num_objects)) 228 return; 229 230 pr_err("\n"); 231 pr_err("This frame has %lu %s:\n", num_objects, 232 num_objects == 1 ? "object" : "objects"); 233 234 while (num_objects--) { 235 unsigned long offset; 236 unsigned long size; 237 238 /* access offset */ 239 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), 240 &offset)) 241 return; 242 /* access size */ 243 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), 244 &size)) 245 return; 246 /* name length (unused) */ 247 if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) 248 return; 249 /* object name */ 250 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), 251 NULL)) 252 return; 253 254 /* Strip line number; without filename it's not very helpful. */ 255 strreplace(token, ':', '\0'); 256 257 /* Finally, print object information. */ 258 pr_err(" [%lu, %lu) '%s'", offset, offset + size, token); 259 } 260 } 261 262 /* Returns true only if the address is on the current task's stack. */ 263 static bool __must_check get_address_stack_frame_info(const void *addr, 264 unsigned long *offset, 265 const char **frame_descr, 266 const void **frame_pc) 267 { 268 unsigned long aligned_addr; 269 unsigned long mem_ptr; 270 const u8 *shadow_bottom; 271 const u8 *shadow_ptr; 272 const unsigned long *frame; 273 274 BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); 275 276 aligned_addr = round_down((unsigned long)addr, sizeof(long)); 277 mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE); 278 shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); 279 shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); 280 281 while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { 282 shadow_ptr--; 283 mem_ptr -= KASAN_GRANULE_SIZE; 284 } 285 286 while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { 287 shadow_ptr--; 288 mem_ptr -= KASAN_GRANULE_SIZE; 289 } 290 291 if (shadow_ptr < shadow_bottom) 292 return false; 293 294 frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE); 295 if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) { 296 pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n", 297 frame[0]); 298 return false; 299 } 300 301 *offset = (unsigned long)addr - (unsigned long)frame; 302 *frame_descr = (const char *)frame[1]; 303 *frame_pc = (void *)frame[2]; 304 305 return true; 306 } 307 308 void kasan_print_address_stack_frame(const void *addr) 309 { 310 unsigned long offset; 311 const char *frame_descr; 312 const void *frame_pc; 313 314 if (WARN_ON(!object_is_on_stack(addr))) 315 return; 316 317 pr_err("The buggy address belongs to stack of task %s/%d\n", 318 current->comm, task_pid_nr(current)); 319 320 if (!get_address_stack_frame_info(addr, &offset, &frame_descr, 321 &frame_pc)) 322 return; 323 324 pr_err(" and is located at offset %lu in frame:\n", offset); 325 pr_err(" %pS\n", frame_pc); 326 327 if (!frame_descr) 328 return; 329 330 print_decoded_frame_descr(frame_descr); 331 } 332 #endif /* CONFIG_KASAN_STACK */ 333 334 #define DEFINE_ASAN_REPORT_LOAD(size) \ 335 void __asan_report_load##size##_noabort(unsigned long addr) \ 336 { \ 337 kasan_report(addr, size, false, _RET_IP_); \ 338 } \ 339 EXPORT_SYMBOL(__asan_report_load##size##_noabort) 340 341 #define DEFINE_ASAN_REPORT_STORE(size) \ 342 void __asan_report_store##size##_noabort(unsigned long addr) \ 343 { \ 344 kasan_report(addr, size, true, _RET_IP_); \ 345 } \ 346 EXPORT_SYMBOL(__asan_report_store##size##_noabort) 347 348 DEFINE_ASAN_REPORT_LOAD(1); 349 DEFINE_ASAN_REPORT_LOAD(2); 350 DEFINE_ASAN_REPORT_LOAD(4); 351 DEFINE_ASAN_REPORT_LOAD(8); 352 DEFINE_ASAN_REPORT_LOAD(16); 353 DEFINE_ASAN_REPORT_STORE(1); 354 DEFINE_ASAN_REPORT_STORE(2); 355 DEFINE_ASAN_REPORT_STORE(4); 356 DEFINE_ASAN_REPORT_STORE(8); 357 DEFINE_ASAN_REPORT_STORE(16); 358 359 void __asan_report_load_n_noabort(unsigned long addr, size_t size) 360 { 361 kasan_report(addr, size, false, _RET_IP_); 362 } 363 EXPORT_SYMBOL(__asan_report_load_n_noabort); 364 365 void __asan_report_store_n_noabort(unsigned long addr, size_t size) 366 { 367 kasan_report(addr, size, true, _RET_IP_); 368 } 369 EXPORT_SYMBOL(__asan_report_store_n_noabort); 370