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 const char *kasan_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_metadata_fetch_row(char *buffer, void *row) 131 { 132 memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW); 133 } 134 135 #ifdef CONFIG_KASAN_STACK 136 static bool __must_check tokenize_frame_descr(const char **frame_descr, 137 char *token, size_t max_tok_len, 138 unsigned long *value) 139 { 140 const char *sep = strchr(*frame_descr, ' '); 141 142 if (sep == NULL) 143 sep = *frame_descr + strlen(*frame_descr); 144 145 if (token != NULL) { 146 const size_t tok_len = sep - *frame_descr; 147 148 if (tok_len + 1 > max_tok_len) { 149 pr_err("KASAN internal error: frame description too long: %s\n", 150 *frame_descr); 151 return false; 152 } 153 154 /* Copy token (+ 1 byte for '\0'). */ 155 strscpy(token, *frame_descr, tok_len + 1); 156 } 157 158 /* Advance frame_descr past separator. */ 159 *frame_descr = sep + 1; 160 161 if (value != NULL && kstrtoul(token, 10, value)) { 162 pr_err("KASAN internal error: not a valid number: %s\n", token); 163 return false; 164 } 165 166 return true; 167 } 168 169 static void print_decoded_frame_descr(const char *frame_descr) 170 { 171 /* 172 * We need to parse the following string: 173 * "n alloc_1 alloc_2 ... alloc_n" 174 * where alloc_i looks like 175 * "offset size len name" 176 * or "offset size len name:line". 177 */ 178 179 char token[64]; 180 unsigned long num_objects; 181 182 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), 183 &num_objects)) 184 return; 185 186 pr_err("\n"); 187 pr_err("This frame has %lu %s:\n", num_objects, 188 num_objects == 1 ? "object" : "objects"); 189 190 while (num_objects--) { 191 unsigned long offset; 192 unsigned long size; 193 194 /* access offset */ 195 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), 196 &offset)) 197 return; 198 /* access size */ 199 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), 200 &size)) 201 return; 202 /* name length (unused) */ 203 if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) 204 return; 205 /* object name */ 206 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), 207 NULL)) 208 return; 209 210 /* Strip line number; without filename it's not very helpful. */ 211 strreplace(token, ':', '\0'); 212 213 /* Finally, print object information. */ 214 pr_err(" [%lu, %lu) '%s'", offset, offset + size, token); 215 } 216 } 217 218 /* Returns true only if the address is on the current task's stack. */ 219 static bool __must_check get_address_stack_frame_info(const void *addr, 220 unsigned long *offset, 221 const char **frame_descr, 222 const void **frame_pc) 223 { 224 unsigned long aligned_addr; 225 unsigned long mem_ptr; 226 const u8 *shadow_bottom; 227 const u8 *shadow_ptr; 228 const unsigned long *frame; 229 230 BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); 231 232 aligned_addr = round_down((unsigned long)addr, sizeof(long)); 233 mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE); 234 shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); 235 shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); 236 237 while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { 238 shadow_ptr--; 239 mem_ptr -= KASAN_GRANULE_SIZE; 240 } 241 242 while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { 243 shadow_ptr--; 244 mem_ptr -= KASAN_GRANULE_SIZE; 245 } 246 247 if (shadow_ptr < shadow_bottom) 248 return false; 249 250 frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE); 251 if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) { 252 pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n", 253 frame[0]); 254 return false; 255 } 256 257 *offset = (unsigned long)addr - (unsigned long)frame; 258 *frame_descr = (const char *)frame[1]; 259 *frame_pc = (void *)frame[2]; 260 261 return true; 262 } 263 264 void kasan_print_address_stack_frame(const void *addr) 265 { 266 unsigned long offset; 267 const char *frame_descr; 268 const void *frame_pc; 269 270 if (WARN_ON(!object_is_on_stack(addr))) 271 return; 272 273 pr_err("The buggy address belongs to stack of task %s/%d\n", 274 current->comm, task_pid_nr(current)); 275 276 if (!get_address_stack_frame_info(addr, &offset, &frame_descr, 277 &frame_pc)) 278 return; 279 280 pr_err(" and is located at offset %lu in frame:\n", offset); 281 pr_err(" %pS\n", frame_pc); 282 283 if (!frame_descr) 284 return; 285 286 print_decoded_frame_descr(frame_descr); 287 } 288 #endif /* CONFIG_KASAN_STACK */ 289 290 #define DEFINE_ASAN_REPORT_LOAD(size) \ 291 void __asan_report_load##size##_noabort(unsigned long addr) \ 292 { \ 293 kasan_report(addr, size, false, _RET_IP_); \ 294 } \ 295 EXPORT_SYMBOL(__asan_report_load##size##_noabort) 296 297 #define DEFINE_ASAN_REPORT_STORE(size) \ 298 void __asan_report_store##size##_noabort(unsigned long addr) \ 299 { \ 300 kasan_report(addr, size, true, _RET_IP_); \ 301 } \ 302 EXPORT_SYMBOL(__asan_report_store##size##_noabort) 303 304 DEFINE_ASAN_REPORT_LOAD(1); 305 DEFINE_ASAN_REPORT_LOAD(2); 306 DEFINE_ASAN_REPORT_LOAD(4); 307 DEFINE_ASAN_REPORT_LOAD(8); 308 DEFINE_ASAN_REPORT_LOAD(16); 309 DEFINE_ASAN_REPORT_STORE(1); 310 DEFINE_ASAN_REPORT_STORE(2); 311 DEFINE_ASAN_REPORT_STORE(4); 312 DEFINE_ASAN_REPORT_STORE(8); 313 DEFINE_ASAN_REPORT_STORE(16); 314 315 void __asan_report_load_n_noabort(unsigned long addr, size_t size) 316 { 317 kasan_report(addr, size, false, _RET_IP_); 318 } 319 EXPORT_SYMBOL(__asan_report_load_n_noabort); 320 321 void __asan_report_store_n_noabort(unsigned long addr, size_t size) 322 { 323 kasan_report(addr, size, true, _RET_IP_); 324 } 325 EXPORT_SYMBOL(__asan_report_store_n_noabort); 326