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e886bf9d | 1 | // SPDX-License-Identifier: GPL-2.0 |
11cd3cd6 AK |
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> | |
11cd3cd6 AK |
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> | |
97fc7122 | 19 | #include <linux/sched/task_stack.h> |
11cd3cd6 AK |
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 | ||
f00748bf | 33 | void *kasan_find_first_bad_addr(void *addr, size_t size) |
11cd3cd6 | 34 | { |
121e8f81 | 35 | void *p = addr; |
11cd3cd6 | 36 | |
b9132800 AK |
37 | if (!addr_has_metadata(p)) |
38 | return p; | |
39 | ||
121e8f81 | 40 | while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p))) |
1f600626 | 41 | p += KASAN_GRANULE_SIZE; |
b9132800 | 42 | |
121e8f81 | 43 | return p; |
11cd3cd6 AK |
44 | } |
45 | ||
8f17febb KYL |
46 | size_t kasan_get_alloc_size(void *object, struct kmem_cache *cache) |
47 | { | |
48 | size_t size = 0; | |
49 | u8 *shadow; | |
50 | ||
51 | /* | |
52 | * Skip the addr_has_metadata check, as this function only operates on | |
53 | * slab memory, which must have metadata. | |
54 | */ | |
55 | ||
56 | /* | |
57 | * The loop below returns 0 for freed objects, for which KASAN cannot | |
58 | * calculate the allocation size based on the metadata. | |
59 | */ | |
60 | shadow = (u8 *)kasan_mem_to_shadow(object); | |
61 | while (size < cache->object_size) { | |
62 | if (*shadow == 0) | |
63 | size += KASAN_GRANULE_SIZE; | |
64 | else if (*shadow >= 1 && *shadow <= KASAN_GRANULE_SIZE - 1) | |
65 | return size + *shadow; | |
66 | else | |
67 | return size; | |
68 | shadow++; | |
69 | } | |
70 | ||
71 | return cache->object_size; | |
72 | } | |
73 | ||
c965cdd6 | 74 | static const char *get_shadow_bug_type(struct kasan_report_info *info) |
11cd3cd6 AK |
75 | { |
76 | const char *bug_type = "unknown-crash"; | |
77 | u8 *shadow_addr; | |
78 | ||
11cd3cd6 AK |
79 | shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr); |
80 | ||
81 | /* | |
1f600626 | 82 | * If shadow byte value is in [0, KASAN_GRANULE_SIZE) we can look |
11cd3cd6 AK |
83 | * at the next shadow byte to determine the type of the bad access. |
84 | */ | |
1f600626 | 85 | if (*shadow_addr > 0 && *shadow_addr <= KASAN_GRANULE_SIZE - 1) |
11cd3cd6 AK |
86 | shadow_addr++; |
87 | ||
88 | switch (*shadow_addr) { | |
1f600626 | 89 | case 0 ... KASAN_GRANULE_SIZE - 1: |
11cd3cd6 AK |
90 | /* |
91 | * In theory it's still possible to see these shadow values | |
92 | * due to a data race in the kernel code. | |
93 | */ | |
94 | bug_type = "out-of-bounds"; | |
95 | break; | |
96 | case KASAN_PAGE_REDZONE: | |
06bc4cf6 | 97 | case KASAN_SLAB_REDZONE: |
11cd3cd6 AK |
98 | bug_type = "slab-out-of-bounds"; |
99 | break; | |
100 | case KASAN_GLOBAL_REDZONE: | |
101 | bug_type = "global-out-of-bounds"; | |
102 | break; | |
103 | case KASAN_STACK_LEFT: | |
104 | case KASAN_STACK_MID: | |
105 | case KASAN_STACK_RIGHT: | |
106 | case KASAN_STACK_PARTIAL: | |
107 | bug_type = "stack-out-of-bounds"; | |
108 | break; | |
06bc4cf6 | 109 | case KASAN_PAGE_FREE: |
8f17febb KYL |
110 | bug_type = "use-after-free"; |
111 | break; | |
06bc4cf6 AK |
112 | case KASAN_SLAB_FREE: |
113 | case KASAN_SLAB_FREETRACK: | |
8f17febb | 114 | bug_type = "slab-use-after-free"; |
11cd3cd6 | 115 | break; |
11cd3cd6 AK |
116 | case KASAN_ALLOCA_LEFT: |
117 | case KASAN_ALLOCA_RIGHT: | |
118 | bug_type = "alloca-out-of-bounds"; | |
119 | break; | |
3c5c3cfb DA |
120 | case KASAN_VMALLOC_INVALID: |
121 | bug_type = "vmalloc-out-of-bounds"; | |
122 | break; | |
11cd3cd6 AK |
123 | } |
124 | ||
125 | return bug_type; | |
126 | } | |
127 | ||
c965cdd6 | 128 | static const char *get_wild_bug_type(struct kasan_report_info *info) |
11cd3cd6 AK |
129 | { |
130 | const char *bug_type = "unknown-crash"; | |
131 | ||
132 | if ((unsigned long)info->access_addr < PAGE_SIZE) | |
133 | bug_type = "null-ptr-deref"; | |
134 | else if ((unsigned long)info->access_addr < TASK_SIZE) | |
135 | bug_type = "user-memory-access"; | |
136 | else | |
137 | bug_type = "wild-memory-access"; | |
138 | ||
139 | return bug_type; | |
140 | } | |
141 | ||
59e6e098 | 142 | static const char *get_bug_type(struct kasan_report_info *info) |
11cd3cd6 | 143 | { |
8cceeff4 WW |
144 | /* |
145 | * If access_size is a negative number, then it has reason to be | |
146 | * defined as out-of-bounds bug type. | |
147 | * | |
148 | * Casting negative numbers to size_t would indeed turn up as | |
149 | * a large size_t and its value will be larger than ULONG_MAX/2, | |
150 | * so that this can qualify as out-of-bounds. | |
151 | */ | |
152 | if (info->access_addr + info->access_size < info->access_addr) | |
153 | return "out-of-bounds"; | |
154 | ||
6882464f | 155 | if (addr_has_metadata(info->access_addr)) |
11cd3cd6 AK |
156 | return get_shadow_bug_type(info); |
157 | return get_wild_bug_type(info); | |
158 | } | |
159 | ||
59e6e098 | 160 | void kasan_complete_mode_report_info(struct kasan_report_info *info) |
b89933e9 AK |
161 | { |
162 | struct kasan_alloc_meta *alloc_meta; | |
59e6e098 | 163 | struct kasan_free_meta *free_meta; |
b89933e9 | 164 | |
dcc57966 AK |
165 | if (!info->bug_type) |
166 | info->bug_type = get_bug_type(info); | |
b89933e9 | 167 | |
59e6e098 AK |
168 | if (!info->cache || !info->object) |
169 | return; | |
b89933e9 | 170 | |
59e6e098 AK |
171 | alloc_meta = kasan_get_alloc_meta(info->cache, info->object); |
172 | if (alloc_meta) | |
173 | memcpy(&info->alloc_track, &alloc_meta->alloc_track, | |
174 | sizeof(info->alloc_track)); | |
175 | ||
176 | if (*(u8 *)kasan_mem_to_shadow(info->object) == KASAN_SLAB_FREETRACK) { | |
177 | /* Free meta must be present with KASAN_SLAB_FREETRACK. */ | |
178 | free_meta = kasan_get_free_meta(info->cache, info->object); | |
179 | memcpy(&info->free_track, &free_meta->free_track, | |
180 | sizeof(info->free_track)); | |
181 | } | |
b89933e9 AK |
182 | } |
183 | ||
f00748bf | 184 | void kasan_metadata_fetch_row(char *buffer, void *row) |
96e0279d AK |
185 | { |
186 | memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW); | |
187 | } | |
188 | ||
88f29765 AK |
189 | void kasan_print_aux_stacks(struct kmem_cache *cache, const void *object) |
190 | { | |
191 | struct kasan_alloc_meta *alloc_meta; | |
192 | ||
193 | alloc_meta = kasan_get_alloc_meta(cache, object); | |
194 | if (!alloc_meta) | |
195 | return; | |
196 | ||
197 | if (alloc_meta->aux_stack[0]) { | |
198 | pr_err("Last potentially related work creation:\n"); | |
199 | stack_depot_print(alloc_meta->aux_stack[0]); | |
200 | pr_err("\n"); | |
201 | } | |
202 | if (alloc_meta->aux_stack[1]) { | |
203 | pr_err("Second to last potentially related work creation:\n"); | |
204 | stack_depot_print(alloc_meta->aux_stack[1]); | |
205 | pr_err("\n"); | |
206 | } | |
207 | } | |
208 | ||
02c58773 | 209 | #ifdef CONFIG_KASAN_STACK |
97fc7122 AK |
210 | static bool __must_check tokenize_frame_descr(const char **frame_descr, |
211 | char *token, size_t max_tok_len, | |
212 | unsigned long *value) | |
213 | { | |
214 | const char *sep = strchr(*frame_descr, ' '); | |
215 | ||
216 | if (sep == NULL) | |
217 | sep = *frame_descr + strlen(*frame_descr); | |
218 | ||
219 | if (token != NULL) { | |
220 | const size_t tok_len = sep - *frame_descr; | |
221 | ||
222 | if (tok_len + 1 > max_tok_len) { | |
223 | pr_err("KASAN internal error: frame description too long: %s\n", | |
224 | *frame_descr); | |
225 | return false; | |
226 | } | |
227 | ||
228 | /* Copy token (+ 1 byte for '\0'). */ | |
f76e0c41 | 229 | strscpy(token, *frame_descr, tok_len + 1); |
97fc7122 AK |
230 | } |
231 | ||
232 | /* Advance frame_descr past separator. */ | |
233 | *frame_descr = sep + 1; | |
234 | ||
235 | if (value != NULL && kstrtoul(token, 10, value)) { | |
236 | pr_err("KASAN internal error: not a valid number: %s\n", token); | |
237 | return false; | |
238 | } | |
239 | ||
240 | return true; | |
241 | } | |
242 | ||
243 | static void print_decoded_frame_descr(const char *frame_descr) | |
244 | { | |
245 | /* | |
246 | * We need to parse the following string: | |
247 | * "n alloc_1 alloc_2 ... alloc_n" | |
248 | * where alloc_i looks like | |
249 | * "offset size len name" | |
250 | * or "offset size len name:line". | |
251 | */ | |
252 | ||
253 | char token[64]; | |
254 | unsigned long num_objects; | |
255 | ||
256 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
257 | &num_objects)) | |
258 | return; | |
259 | ||
260 | pr_err("\n"); | |
16347c31 | 261 | pr_err("This frame has %lu %s:\n", num_objects, |
97fc7122 AK |
262 | num_objects == 1 ? "object" : "objects"); |
263 | ||
264 | while (num_objects--) { | |
265 | unsigned long offset; | |
266 | unsigned long size; | |
267 | ||
268 | /* access offset */ | |
269 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
270 | &offset)) | |
271 | return; | |
272 | /* access size */ | |
273 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
274 | &size)) | |
275 | return; | |
276 | /* name length (unused) */ | |
277 | if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) | |
278 | return; | |
279 | /* object name */ | |
280 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
281 | NULL)) | |
282 | return; | |
283 | ||
284 | /* Strip line number; without filename it's not very helpful. */ | |
285 | strreplace(token, ':', '\0'); | |
286 | ||
287 | /* Finally, print object information. */ | |
288 | pr_err(" [%lu, %lu) '%s'", offset, offset + size, token); | |
289 | } | |
290 | } | |
291 | ||
0f9b35f3 | 292 | /* Returns true only if the address is on the current task's stack. */ |
97fc7122 AK |
293 | static bool __must_check get_address_stack_frame_info(const void *addr, |
294 | unsigned long *offset, | |
295 | const char **frame_descr, | |
296 | const void **frame_pc) | |
297 | { | |
298 | unsigned long aligned_addr; | |
299 | unsigned long mem_ptr; | |
300 | const u8 *shadow_bottom; | |
301 | const u8 *shadow_ptr; | |
302 | const unsigned long *frame; | |
303 | ||
304 | BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); | |
305 | ||
97fc7122 AK |
306 | aligned_addr = round_down((unsigned long)addr, sizeof(long)); |
307 | mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE); | |
308 | shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); | |
309 | shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); | |
310 | ||
311 | while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { | |
312 | shadow_ptr--; | |
313 | mem_ptr -= KASAN_GRANULE_SIZE; | |
314 | } | |
315 | ||
316 | while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { | |
317 | shadow_ptr--; | |
318 | mem_ptr -= KASAN_GRANULE_SIZE; | |
319 | } | |
320 | ||
321 | if (shadow_ptr < shadow_bottom) | |
322 | return false; | |
323 | ||
324 | frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE); | |
325 | if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) { | |
326 | pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n", | |
327 | frame[0]); | |
328 | return false; | |
329 | } | |
330 | ||
331 | *offset = (unsigned long)addr - (unsigned long)frame; | |
332 | *frame_descr = (const char *)frame[1]; | |
333 | *frame_pc = (void *)frame[2]; | |
334 | ||
335 | return true; | |
336 | } | |
337 | ||
f00748bf | 338 | void kasan_print_address_stack_frame(const void *addr) |
97fc7122 AK |
339 | { |
340 | unsigned long offset; | |
341 | const char *frame_descr; | |
342 | const void *frame_pc; | |
343 | ||
0f9b35f3 AK |
344 | if (WARN_ON(!object_is_on_stack(addr))) |
345 | return; | |
346 | ||
16347c31 AK |
347 | pr_err("The buggy address belongs to stack of task %s/%d\n", |
348 | current->comm, task_pid_nr(current)); | |
349 | ||
97fc7122 AK |
350 | if (!get_address_stack_frame_info(addr, &offset, &frame_descr, |
351 | &frame_pc)) | |
352 | return; | |
353 | ||
16347c31 | 354 | pr_err(" and is located at offset %lu in frame:\n", offset); |
97fc7122 AK |
355 | pr_err(" %pS\n", frame_pc); |
356 | ||
357 | if (!frame_descr) | |
358 | return; | |
359 | ||
360 | print_decoded_frame_descr(frame_descr); | |
361 | } | |
362 | #endif /* CONFIG_KASAN_STACK */ | |
363 | ||
11cd3cd6 AK |
364 | #define DEFINE_ASAN_REPORT_LOAD(size) \ |
365 | void __asan_report_load##size##_noabort(unsigned long addr) \ | |
366 | { \ | |
367 | kasan_report(addr, size, false, _RET_IP_); \ | |
368 | } \ | |
369 | EXPORT_SYMBOL(__asan_report_load##size##_noabort) | |
370 | ||
371 | #define DEFINE_ASAN_REPORT_STORE(size) \ | |
372 | void __asan_report_store##size##_noabort(unsigned long addr) \ | |
373 | { \ | |
374 | kasan_report(addr, size, true, _RET_IP_); \ | |
375 | } \ | |
376 | EXPORT_SYMBOL(__asan_report_store##size##_noabort) | |
377 | ||
378 | DEFINE_ASAN_REPORT_LOAD(1); | |
379 | DEFINE_ASAN_REPORT_LOAD(2); | |
380 | DEFINE_ASAN_REPORT_LOAD(4); | |
381 | DEFINE_ASAN_REPORT_LOAD(8); | |
382 | DEFINE_ASAN_REPORT_LOAD(16); | |
383 | DEFINE_ASAN_REPORT_STORE(1); | |
384 | DEFINE_ASAN_REPORT_STORE(2); | |
385 | DEFINE_ASAN_REPORT_STORE(4); | |
386 | DEFINE_ASAN_REPORT_STORE(8); | |
387 | DEFINE_ASAN_REPORT_STORE(16); | |
388 | ||
389 | void __asan_report_load_n_noabort(unsigned long addr, size_t size) | |
390 | { | |
391 | kasan_report(addr, size, false, _RET_IP_); | |
392 | } | |
393 | EXPORT_SYMBOL(__asan_report_load_n_noabort); | |
394 | ||
395 | void __asan_report_store_n_noabort(unsigned long addr, size_t size) | |
396 | { | |
397 | kasan_report(addr, size, true, _RET_IP_); | |
398 | } | |
399 | EXPORT_SYMBOL(__asan_report_store_n_noabort); |