report_generic.c 8.5 KB

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  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. #include <linux/bitops.h>
  12. #include <linux/ftrace.h>
  13. #include <linux/init.h>
  14. #include <linux/kernel.h>
  15. #include <linux/mm.h>
  16. #include <linux/printk.h>
  17. #include <linux/sched.h>
  18. #include <linux/sched/task_stack.h>
  19. #include <linux/slab.h>
  20. #include <linux/stackdepot.h>
  21. #include <linux/stacktrace.h>
  22. #include <linux/string.h>
  23. #include <linux/types.h>
  24. #include <linux/kasan.h>
  25. #include <linux/module.h>
  26. #include <asm/sections.h>
  27. #include "kasan.h"
  28. #include "../slab.h"
  29. void *kasan_find_first_bad_addr(void *addr, size_t size)
  30. {
  31. void *p = addr;
  32. while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
  33. p += KASAN_GRANULE_SIZE;
  34. return p;
  35. }
  36. static const char *get_shadow_bug_type(struct kasan_access_info *info)
  37. {
  38. const char *bug_type = "unknown-crash";
  39. u8 *shadow_addr;
  40. shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
  41. /*
  42. * If shadow byte value is in [0, KASAN_GRANULE_SIZE) we can look
  43. * at the next shadow byte to determine the type of the bad access.
  44. */
  45. if (*shadow_addr > 0 && *shadow_addr <= KASAN_GRANULE_SIZE - 1)
  46. shadow_addr++;
  47. switch (*shadow_addr) {
  48. case 0 ... KASAN_GRANULE_SIZE - 1:
  49. /*
  50. * In theory it's still possible to see these shadow values
  51. * due to a data race in the kernel code.
  52. */
  53. bug_type = "out-of-bounds";
  54. break;
  55. case KASAN_PAGE_REDZONE:
  56. case KASAN_KMALLOC_REDZONE:
  57. bug_type = "slab-out-of-bounds";
  58. break;
  59. case KASAN_GLOBAL_REDZONE:
  60. bug_type = "global-out-of-bounds";
  61. break;
  62. case KASAN_STACK_LEFT:
  63. case KASAN_STACK_MID:
  64. case KASAN_STACK_RIGHT:
  65. case KASAN_STACK_PARTIAL:
  66. bug_type = "stack-out-of-bounds";
  67. break;
  68. case KASAN_FREE_PAGE:
  69. case KASAN_KMALLOC_FREE:
  70. case KASAN_KMALLOC_FREETRACK:
  71. bug_type = "use-after-free";
  72. break;
  73. case KASAN_ALLOCA_LEFT:
  74. case KASAN_ALLOCA_RIGHT:
  75. bug_type = "alloca-out-of-bounds";
  76. break;
  77. case KASAN_VMALLOC_INVALID:
  78. bug_type = "vmalloc-out-of-bounds";
  79. break;
  80. }
  81. return bug_type;
  82. }
  83. static const char *get_wild_bug_type(struct kasan_access_info *info)
  84. {
  85. const char *bug_type = "unknown-crash";
  86. if ((unsigned long)info->access_addr < PAGE_SIZE)
  87. bug_type = "null-ptr-deref";
  88. else if ((unsigned long)info->access_addr < TASK_SIZE)
  89. bug_type = "user-memory-access";
  90. else
  91. bug_type = "wild-memory-access";
  92. return bug_type;
  93. }
  94. const char *kasan_get_bug_type(struct kasan_access_info *info)
  95. {
  96. /*
  97. * If access_size is a negative number, then it has reason to be
  98. * defined as out-of-bounds bug type.
  99. *
  100. * Casting negative numbers to size_t would indeed turn up as
  101. * a large size_t and its value will be larger than ULONG_MAX/2,
  102. * so that this can qualify as out-of-bounds.
  103. */
  104. if (info->access_addr + info->access_size < info->access_addr)
  105. return "out-of-bounds";
  106. if (addr_has_metadata(info->access_addr))
  107. return get_shadow_bug_type(info);
  108. return get_wild_bug_type(info);
  109. }
  110. void kasan_metadata_fetch_row(char *buffer, void *row)
  111. {
  112. memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW);
  113. }
  114. #ifdef CONFIG_KASAN_STACK
  115. static bool __must_check tokenize_frame_descr(const char **frame_descr,
  116. char *token, size_t max_tok_len,
  117. unsigned long *value)
  118. {
  119. const char *sep = strchr(*frame_descr, ' ');
  120. if (sep == NULL)
  121. sep = *frame_descr + strlen(*frame_descr);
  122. if (token != NULL) {
  123. const size_t tok_len = sep - *frame_descr;
  124. if (tok_len + 1 > max_tok_len) {
  125. pr_err("KASAN internal error: frame description too long: %s\n",
  126. *frame_descr);
  127. return false;
  128. }
  129. /* Copy token (+ 1 byte for '\0'). */
  130. strscpy(token, *frame_descr, tok_len + 1);
  131. }
  132. /* Advance frame_descr past separator. */
  133. *frame_descr = sep + 1;
  134. if (value != NULL && kstrtoul(token, 10, value)) {
  135. pr_err("KASAN internal error: not a valid number: %s\n", token);
  136. return false;
  137. }
  138. return true;
  139. }
  140. static void print_decoded_frame_descr(const char *frame_descr)
  141. {
  142. /*
  143. * We need to parse the following string:
  144. * "n alloc_1 alloc_2 ... alloc_n"
  145. * where alloc_i looks like
  146. * "offset size len name"
  147. * or "offset size len name:line".
  148. */
  149. char token[64];
  150. unsigned long num_objects;
  151. if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
  152. &num_objects))
  153. return;
  154. pr_err("\n");
  155. pr_err("this frame has %lu %s:\n", num_objects,
  156. num_objects == 1 ? "object" : "objects");
  157. while (num_objects--) {
  158. unsigned long offset;
  159. unsigned long size;
  160. /* access offset */
  161. if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
  162. &offset))
  163. return;
  164. /* access size */
  165. if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
  166. &size))
  167. return;
  168. /* name length (unused) */
  169. if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL))
  170. return;
  171. /* object name */
  172. if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
  173. NULL))
  174. return;
  175. /* Strip line number; without filename it's not very helpful. */
  176. strreplace(token, ':', '\0');
  177. /* Finally, print object information. */
  178. pr_err(" [%lu, %lu) '%s'", offset, offset + size, token);
  179. }
  180. }
  181. static bool __must_check get_address_stack_frame_info(const void *addr,
  182. unsigned long *offset,
  183. const char **frame_descr,
  184. const void **frame_pc)
  185. {
  186. unsigned long aligned_addr;
  187. unsigned long mem_ptr;
  188. const u8 *shadow_bottom;
  189. const u8 *shadow_ptr;
  190. const unsigned long *frame;
  191. BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP));
  192. /*
  193. * NOTE: We currently only support printing frame information for
  194. * accesses to the task's own stack.
  195. */
  196. if (!object_is_on_stack(addr))
  197. return false;
  198. aligned_addr = round_down((unsigned long)addr, sizeof(long));
  199. mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE);
  200. shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr);
  201. shadow_bottom = kasan_mem_to_shadow(end_of_stack(current));
  202. while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) {
  203. shadow_ptr--;
  204. mem_ptr -= KASAN_GRANULE_SIZE;
  205. }
  206. while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) {
  207. shadow_ptr--;
  208. mem_ptr -= KASAN_GRANULE_SIZE;
  209. }
  210. if (shadow_ptr < shadow_bottom)
  211. return false;
  212. frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE);
  213. if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) {
  214. pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n",
  215. frame[0]);
  216. return false;
  217. }
  218. *offset = (unsigned long)addr - (unsigned long)frame;
  219. *frame_descr = (const char *)frame[1];
  220. *frame_pc = (void *)frame[2];
  221. return true;
  222. }
  223. void kasan_print_address_stack_frame(const void *addr)
  224. {
  225. unsigned long offset;
  226. const char *frame_descr;
  227. const void *frame_pc;
  228. if (!get_address_stack_frame_info(addr, &offset, &frame_descr,
  229. &frame_pc))
  230. return;
  231. /*
  232. * get_address_stack_frame_info only returns true if the given addr is
  233. * on the current task's stack.
  234. */
  235. pr_err("\n");
  236. pr_err("addr %px is located in stack of task %s/%d at offset %lu in frame:\n",
  237. addr, current->comm, task_pid_nr(current), offset);
  238. pr_err(" %pS\n", frame_pc);
  239. if (!frame_descr)
  240. return;
  241. print_decoded_frame_descr(frame_descr);
  242. }
  243. #endif /* CONFIG_KASAN_STACK */
  244. #define DEFINE_ASAN_REPORT_LOAD(size) \
  245. void __asan_report_load##size##_noabort(unsigned long addr) \
  246. { \
  247. kasan_report(addr, size, false, _RET_IP_); \
  248. } \
  249. EXPORT_SYMBOL(__asan_report_load##size##_noabort)
  250. #define DEFINE_ASAN_REPORT_STORE(size) \
  251. void __asan_report_store##size##_noabort(unsigned long addr) \
  252. { \
  253. kasan_report(addr, size, true, _RET_IP_); \
  254. } \
  255. EXPORT_SYMBOL(__asan_report_store##size##_noabort)
  256. DEFINE_ASAN_REPORT_LOAD(1);
  257. DEFINE_ASAN_REPORT_LOAD(2);
  258. DEFINE_ASAN_REPORT_LOAD(4);
  259. DEFINE_ASAN_REPORT_LOAD(8);
  260. DEFINE_ASAN_REPORT_LOAD(16);
  261. DEFINE_ASAN_REPORT_STORE(1);
  262. DEFINE_ASAN_REPORT_STORE(2);
  263. DEFINE_ASAN_REPORT_STORE(4);
  264. DEFINE_ASAN_REPORT_STORE(8);
  265. DEFINE_ASAN_REPORT_STORE(16);
  266. void __asan_report_load_n_noabort(unsigned long addr, size_t size)
  267. {
  268. kasan_report(addr, size, false, _RET_IP_);
  269. }
  270. EXPORT_SYMBOL(__asan_report_load_n_noabort);
  271. void __asan_report_store_n_noabort(unsigned long addr, size_t size)
  272. {
  273. kasan_report(addr, size, true, _RET_IP_);
  274. }
  275. EXPORT_SYMBOL(__asan_report_store_n_noabort);