Commit | Line | Data |
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e886bf9d | 1 | // SPDX-License-Identifier: GPL-2.0 |
0b24becc | 2 | /* |
11cd3cd6 | 3 | * This file contains common generic and tag-based KASAN error reporting code. |
0b24becc AR |
4 | * |
5 | * Copyright (c) 2014 Samsung Electronics Co., Ltd. | |
2baf9e89 | 6 | * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> |
0b24becc | 7 | * |
5d0926ef | 8 | * Some code borrowed from https://github.com/xairy/kasan-prototype by |
5f21f3a8 | 9 | * Andrey Konovalov <andreyknvl@gmail.com> |
0b24becc AR |
10 | * |
11 | * This program is free software; you can redistribute it and/or modify | |
12 | * it under the terms of the GNU General Public License version 2 as | |
13 | * published by the Free Software Foundation. | |
14 | * | |
15 | */ | |
16 | ||
b0845ce5 | 17 | #include <linux/bitops.h> |
4f40c6e5 | 18 | #include <linux/ftrace.h> |
b0845ce5 | 19 | #include <linux/init.h> |
0b24becc AR |
20 | #include <linux/kernel.h> |
21 | #include <linux/mm.h> | |
22 | #include <linux/printk.h> | |
23 | #include <linux/sched.h> | |
24 | #include <linux/slab.h> | |
cd11016e | 25 | #include <linux/stackdepot.h> |
0b24becc AR |
26 | #include <linux/stacktrace.h> |
27 | #include <linux/string.h> | |
28 | #include <linux/types.h> | |
29 | #include <linux/kasan.h> | |
527f215b | 30 | #include <linux/module.h> |
e8969219 | 31 | #include <linux/sched/task_stack.h> |
0b24becc | 32 | |
bebf56a1 AR |
33 | #include <asm/sections.h> |
34 | ||
0b24becc | 35 | #include "kasan.h" |
0316bec2 | 36 | #include "../slab.h" |
0b24becc AR |
37 | |
38 | /* Shadow layout customization. */ | |
39 | #define SHADOW_BYTES_PER_BLOCK 1 | |
40 | #define SHADOW_BLOCKS_PER_ROW 16 | |
41 | #define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK) | |
42 | #define SHADOW_ROWS_AROUND_ADDR 2 | |
43 | ||
11cd3cd6 | 44 | static unsigned long kasan_flags; |
0b24becc | 45 | |
11cd3cd6 AK |
46 | #define KASAN_BIT_REPORTED 0 |
47 | #define KASAN_BIT_MULTI_SHOT 1 | |
5e82cd12 | 48 | |
11cd3cd6 | 49 | bool kasan_save_enable_multi_shot(void) |
0b24becc | 50 | { |
11cd3cd6 | 51 | return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); |
5e82cd12 | 52 | } |
11cd3cd6 | 53 | EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot); |
5e82cd12 | 54 | |
11cd3cd6 | 55 | void kasan_restore_multi_shot(bool enabled) |
5e82cd12 | 56 | { |
11cd3cd6 AK |
57 | if (!enabled) |
58 | clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); | |
5e82cd12 | 59 | } |
11cd3cd6 | 60 | EXPORT_SYMBOL_GPL(kasan_restore_multi_shot); |
5e82cd12 | 61 | |
11cd3cd6 | 62 | static int __init kasan_set_multi_shot(char *str) |
7d418f7b | 63 | { |
11cd3cd6 AK |
64 | set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); |
65 | return 1; | |
7d418f7b | 66 | } |
11cd3cd6 | 67 | __setup("kasan_multi_shot", kasan_set_multi_shot); |
7d418f7b | 68 | |
121e8f81 | 69 | static void print_error_description(struct kasan_access_info *info) |
5e82cd12 | 70 | { |
7f0a84c2 | 71 | pr_err("BUG: KASAN: %s in %pS\n", |
121e8f81 | 72 | get_bug_type(info), (void *)info->ip); |
6424f6bb | 73 | pr_err("%s of size %zu at addr %px by task %s/%d\n", |
7d418f7b | 74 | info->is_write ? "Write" : "Read", info->access_size, |
7f0a84c2 | 75 | info->access_addr, current->comm, task_pid_nr(current)); |
0b24becc AR |
76 | } |
77 | ||
7e088978 AR |
78 | static DEFINE_SPINLOCK(report_lock); |
79 | ||
11cd3cd6 | 80 | static void start_report(unsigned long *flags) |
7e088978 AR |
81 | { |
82 | /* | |
83 | * Make sure we don't end up in loop. | |
84 | */ | |
85 | kasan_disable_current(); | |
86 | spin_lock_irqsave(&report_lock, *flags); | |
87 | pr_err("==================================================================\n"); | |
88 | } | |
89 | ||
11cd3cd6 | 90 | static void end_report(unsigned long *flags) |
7e088978 AR |
91 | { |
92 | pr_err("==================================================================\n"); | |
93 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); | |
94 | spin_unlock_irqrestore(&report_lock, *flags); | |
5c5c1f36 DV |
95 | if (panic_on_warn) |
96 | panic("panic_on_warn set ...\n"); | |
7e088978 AR |
97 | kasan_enable_current(); |
98 | } | |
99 | ||
b6b72f49 | 100 | static void print_track(struct kasan_track *track, const char *prefix) |
7ed2f9e6 | 101 | { |
b6b72f49 | 102 | pr_err("%s by task %u:\n", prefix, track->pid); |
cd11016e | 103 | if (track->stack) { |
880e049c TG |
104 | unsigned long *entries; |
105 | unsigned int nr_entries; | |
cd11016e | 106 | |
880e049c TG |
107 | nr_entries = stack_depot_fetch(track->stack, &entries); |
108 | stack_trace_print(entries, nr_entries, 0); | |
cd11016e AP |
109 | } else { |
110 | pr_err("(stack is not available)\n"); | |
111 | } | |
7ed2f9e6 AP |
112 | } |
113 | ||
db429f16 AK |
114 | static struct page *addr_to_page(const void *addr) |
115 | { | |
116 | if ((addr >= (void *)PAGE_OFFSET) && | |
117 | (addr < high_memory)) | |
118 | return virt_to_head_page(addr); | |
119 | return NULL; | |
120 | } | |
121 | ||
0c06f1f8 AK |
122 | static void describe_object_addr(struct kmem_cache *cache, void *object, |
123 | const void *addr) | |
7ed2f9e6 | 124 | { |
0c06f1f8 AK |
125 | unsigned long access_addr = (unsigned long)addr; |
126 | unsigned long object_addr = (unsigned long)object; | |
127 | const char *rel_type; | |
128 | int rel_bytes; | |
7ed2f9e6 | 129 | |
6424f6bb | 130 | pr_err("The buggy address belongs to the object at %px\n" |
0c06f1f8 AK |
131 | " which belongs to the cache %s of size %d\n", |
132 | object, cache->name, cache->object_size); | |
47b5c2a0 | 133 | |
0c06f1f8 | 134 | if (!addr) |
7ed2f9e6 | 135 | return; |
b3cbd9bf | 136 | |
0c06f1f8 AK |
137 | if (access_addr < object_addr) { |
138 | rel_type = "to the left"; | |
139 | rel_bytes = object_addr - access_addr; | |
140 | } else if (access_addr >= object_addr + cache->object_size) { | |
141 | rel_type = "to the right"; | |
142 | rel_bytes = access_addr - (object_addr + cache->object_size); | |
143 | } else { | |
144 | rel_type = "inside"; | |
145 | rel_bytes = access_addr - object_addr; | |
146 | } | |
147 | ||
148 | pr_err("The buggy address is located %d bytes %s of\n" | |
6424f6bb | 149 | " %d-byte region [%px, %px)\n", |
0c06f1f8 AK |
150 | rel_bytes, rel_type, cache->object_size, (void *)object_addr, |
151 | (void *)(object_addr + cache->object_size)); | |
152 | } | |
153 | ||
154 | static void describe_object(struct kmem_cache *cache, void *object, | |
155 | const void *addr) | |
156 | { | |
157 | struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); | |
158 | ||
159 | if (cache->flags & SLAB_KASAN) { | |
160 | print_track(&alloc_info->alloc_track, "Allocated"); | |
b1938599 | 161 | pr_err("\n"); |
0c06f1f8 | 162 | print_track(&alloc_info->free_track, "Freed"); |
b1938599 | 163 | pr_err("\n"); |
0c06f1f8 AK |
164 | } |
165 | ||
166 | describe_object_addr(cache, object, addr); | |
7ed2f9e6 | 167 | } |
7ed2f9e6 | 168 | |
11cd3cd6 AK |
169 | static inline bool kernel_or_module_addr(const void *addr) |
170 | { | |
171 | if (addr >= (void *)_stext && addr < (void *)_end) | |
172 | return true; | |
173 | if (is_module_address((unsigned long)addr)) | |
174 | return true; | |
175 | return false; | |
176 | } | |
177 | ||
178 | static inline bool init_task_stack_addr(const void *addr) | |
179 | { | |
180 | return addr >= (void *)&init_thread_union.stack && | |
181 | (addr <= (void *)&init_thread_union.stack + | |
182 | sizeof(init_thread_union.stack)); | |
183 | } | |
184 | ||
e8969219 ME |
185 | static bool __must_check tokenize_frame_descr(const char **frame_descr, |
186 | char *token, size_t max_tok_len, | |
187 | unsigned long *value) | |
188 | { | |
189 | const char *sep = strchr(*frame_descr, ' '); | |
190 | ||
191 | if (sep == NULL) | |
192 | sep = *frame_descr + strlen(*frame_descr); | |
193 | ||
194 | if (token != NULL) { | |
195 | const size_t tok_len = sep - *frame_descr; | |
196 | ||
197 | if (tok_len + 1 > max_tok_len) { | |
198 | pr_err("KASAN internal error: frame description too long: %s\n", | |
199 | *frame_descr); | |
200 | return false; | |
201 | } | |
202 | ||
203 | /* Copy token (+ 1 byte for '\0'). */ | |
204 | strlcpy(token, *frame_descr, tok_len + 1); | |
205 | } | |
206 | ||
207 | /* Advance frame_descr past separator. */ | |
208 | *frame_descr = sep + 1; | |
209 | ||
210 | if (value != NULL && kstrtoul(token, 10, value)) { | |
211 | pr_err("KASAN internal error: not a valid number: %s\n", token); | |
212 | return false; | |
213 | } | |
214 | ||
215 | return true; | |
216 | } | |
217 | ||
218 | static void print_decoded_frame_descr(const char *frame_descr) | |
219 | { | |
220 | /* | |
221 | * We need to parse the following string: | |
222 | * "n alloc_1 alloc_2 ... alloc_n" | |
223 | * where alloc_i looks like | |
224 | * "offset size len name" | |
225 | * or "offset size len name:line". | |
226 | */ | |
227 | ||
228 | char token[64]; | |
229 | unsigned long num_objects; | |
230 | ||
231 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
232 | &num_objects)) | |
233 | return; | |
234 | ||
235 | pr_err("\n"); | |
236 | pr_err("this frame has %lu %s:\n", num_objects, | |
237 | num_objects == 1 ? "object" : "objects"); | |
238 | ||
239 | while (num_objects--) { | |
240 | unsigned long offset; | |
241 | unsigned long size; | |
242 | ||
243 | /* access offset */ | |
244 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
245 | &offset)) | |
246 | return; | |
247 | /* access size */ | |
248 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
249 | &size)) | |
250 | return; | |
251 | /* name length (unused) */ | |
252 | if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) | |
253 | return; | |
254 | /* object name */ | |
255 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
256 | NULL)) | |
257 | return; | |
258 | ||
259 | /* Strip line number; without filename it's not very helpful. */ | |
260 | strreplace(token, ':', '\0'); | |
261 | ||
262 | /* Finally, print object information. */ | |
263 | pr_err(" [%lu, %lu) '%s'", offset, offset + size, token); | |
264 | } | |
265 | } | |
266 | ||
267 | static bool __must_check get_address_stack_frame_info(const void *addr, | |
268 | unsigned long *offset, | |
269 | const char **frame_descr, | |
270 | const void **frame_pc) | |
271 | { | |
272 | unsigned long aligned_addr; | |
273 | unsigned long mem_ptr; | |
274 | const u8 *shadow_bottom; | |
275 | const u8 *shadow_ptr; | |
276 | const unsigned long *frame; | |
277 | ||
278 | BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); | |
279 | ||
280 | /* | |
281 | * NOTE: We currently only support printing frame information for | |
282 | * accesses to the task's own stack. | |
283 | */ | |
284 | if (!object_is_on_stack(addr)) | |
285 | return false; | |
286 | ||
287 | aligned_addr = round_down((unsigned long)addr, sizeof(long)); | |
288 | mem_ptr = round_down(aligned_addr, KASAN_SHADOW_SCALE_SIZE); | |
289 | shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); | |
290 | shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); | |
291 | ||
292 | while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { | |
293 | shadow_ptr--; | |
294 | mem_ptr -= KASAN_SHADOW_SCALE_SIZE; | |
295 | } | |
296 | ||
297 | while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { | |
298 | shadow_ptr--; | |
299 | mem_ptr -= KASAN_SHADOW_SCALE_SIZE; | |
300 | } | |
301 | ||
302 | if (shadow_ptr < shadow_bottom) | |
303 | return false; | |
304 | ||
305 | frame = (const unsigned long *)(mem_ptr + KASAN_SHADOW_SCALE_SIZE); | |
306 | if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) { | |
307 | pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n", | |
308 | frame[0]); | |
309 | return false; | |
310 | } | |
311 | ||
312 | *offset = (unsigned long)addr - (unsigned long)frame; | |
313 | *frame_descr = (const char *)frame[1]; | |
314 | *frame_pc = (void *)frame[2]; | |
315 | ||
316 | return true; | |
317 | } | |
318 | ||
319 | static void print_address_stack_frame(const void *addr) | |
320 | { | |
321 | unsigned long offset; | |
322 | const char *frame_descr; | |
323 | const void *frame_pc; | |
324 | ||
325 | if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) | |
326 | return; | |
327 | ||
328 | if (!get_address_stack_frame_info(addr, &offset, &frame_descr, | |
329 | &frame_pc)) | |
330 | return; | |
331 | ||
332 | /* | |
333 | * get_address_stack_frame_info only returns true if the given addr is | |
334 | * on the current task's stack. | |
335 | */ | |
336 | pr_err("\n"); | |
337 | pr_err("addr %px is located in stack of task %s/%d at offset %lu in frame:\n", | |
338 | addr, current->comm, task_pid_nr(current), offset); | |
339 | pr_err(" %pS\n", frame_pc); | |
340 | ||
341 | if (!frame_descr) | |
342 | return; | |
343 | ||
344 | print_decoded_frame_descr(frame_descr); | |
345 | } | |
346 | ||
5ab6d91a | 347 | static void print_address_description(void *addr) |
0b24becc | 348 | { |
db429f16 | 349 | struct page *page = addr_to_page(addr); |
b8c73fc2 | 350 | |
db429f16 | 351 | dump_stack(); |
b1938599 | 352 | pr_err("\n"); |
db429f16 AK |
353 | |
354 | if (page && PageSlab(page)) { | |
355 | struct kmem_cache *cache = page->slab_cache; | |
0c06f1f8 | 356 | void *object = nearest_obj(cache, page, addr); |
db429f16 | 357 | |
0c06f1f8 | 358 | describe_object(cache, object, addr); |
b8c73fc2 AR |
359 | } |
360 | ||
430a05f9 AK |
361 | if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) { |
362 | pr_err("The buggy address belongs to the variable:\n"); | |
363 | pr_err(" %pS\n", addr); | |
364 | } | |
365 | ||
366 | if (page) { | |
367 | pr_err("The buggy address belongs to the page:\n"); | |
368 | dump_page(page, "kasan: bad access detected"); | |
bebf56a1 | 369 | } |
e8969219 ME |
370 | |
371 | print_address_stack_frame(addr); | |
0b24becc AR |
372 | } |
373 | ||
374 | static bool row_is_guilty(const void *row, const void *guilty) | |
375 | { | |
376 | return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); | |
377 | } | |
378 | ||
379 | static int shadow_pointer_offset(const void *row, const void *shadow) | |
380 | { | |
381 | /* The length of ">ff00ff00ff00ff00: " is | |
382 | * 3 + (BITS_PER_LONG/8)*2 chars. | |
383 | */ | |
384 | return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + | |
385 | (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; | |
386 | } | |
387 | ||
388 | static void print_shadow_for_address(const void *addr) | |
389 | { | |
390 | int i; | |
391 | const void *shadow = kasan_mem_to_shadow(addr); | |
392 | const void *shadow_row; | |
393 | ||
394 | shadow_row = (void *)round_down((unsigned long)shadow, | |
395 | SHADOW_BYTES_PER_ROW) | |
396 | - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; | |
397 | ||
398 | pr_err("Memory state around the buggy address:\n"); | |
399 | ||
400 | for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) { | |
401 | const void *kaddr = kasan_shadow_to_mem(shadow_row); | |
402 | char buffer[4 + (BITS_PER_LONG/8)*2]; | |
f2377d4e | 403 | char shadow_buf[SHADOW_BYTES_PER_ROW]; |
0b24becc AR |
404 | |
405 | snprintf(buffer, sizeof(buffer), | |
6424f6bb | 406 | (i == 0) ? ">%px: " : " %px: ", kaddr); |
f2377d4e AK |
407 | /* |
408 | * We should not pass a shadow pointer to generic | |
409 | * function, because generic functions may try to | |
410 | * access kasan mapping for the passed address. | |
411 | */ | |
f2377d4e | 412 | memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW); |
0b24becc AR |
413 | print_hex_dump(KERN_ERR, buffer, |
414 | DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, | |
f2377d4e | 415 | shadow_buf, SHADOW_BYTES_PER_ROW, 0); |
0b24becc AR |
416 | |
417 | if (row_is_guilty(shadow_row, shadow)) | |
418 | pr_err("%*c\n", | |
419 | shadow_pointer_offset(shadow_row, shadow), | |
420 | '^'); | |
421 | ||
422 | shadow_row += SHADOW_BYTES_PER_ROW; | |
423 | } | |
424 | } | |
425 | ||
11cd3cd6 AK |
426 | static bool report_enabled(void) |
427 | { | |
428 | if (current->kasan_depth) | |
429 | return false; | |
430 | if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) | |
431 | return true; | |
432 | return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); | |
433 | } | |
434 | ||
ee3ce779 | 435 | void kasan_report_invalid_free(void *object, unsigned long ip) |
5ab6d91a AK |
436 | { |
437 | unsigned long flags; | |
438 | ||
11cd3cd6 | 439 | start_report(&flags); |
ee3ce779 | 440 | pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip); |
121e8f81 AK |
441 | print_tags(get_tag(object), reset_tag(object)); |
442 | object = reset_tag(object); | |
b1938599 | 443 | pr_err("\n"); |
5ab6d91a | 444 | print_address_description(object); |
b1938599 | 445 | pr_err("\n"); |
5ab6d91a | 446 | print_shadow_for_address(object); |
11cd3cd6 | 447 | end_report(&flags); |
5ab6d91a AK |
448 | } |
449 | ||
57b78a62 | 450 | void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) |
0b24becc AR |
451 | { |
452 | struct kasan_access_info info; | |
121e8f81 AK |
453 | void *tagged_addr; |
454 | void *untagged_addr; | |
455 | unsigned long flags; | |
0b24becc | 456 | |
11cd3cd6 | 457 | if (likely(!report_enabled())) |
0b24becc AR |
458 | return; |
459 | ||
4f40c6e5 PZ |
460 | disable_trace_on_warning(); |
461 | ||
121e8f81 AK |
462 | tagged_addr = (void *)addr; |
463 | untagged_addr = reset_tag(tagged_addr); | |
464 | ||
465 | info.access_addr = tagged_addr; | |
466 | if (addr_has_shadow(untagged_addr)) | |
467 | info.first_bad_addr = find_first_bad_addr(tagged_addr, size); | |
468 | else | |
469 | info.first_bad_addr = untagged_addr; | |
0b24becc AR |
470 | info.access_size = size; |
471 | info.is_write = is_write; | |
472 | info.ip = ip; | |
e9121076 | 473 | |
121e8f81 AK |
474 | start_report(&flags); |
475 | ||
476 | print_error_description(&info); | |
477 | if (addr_has_shadow(untagged_addr)) | |
478 | print_tags(get_tag(tagged_addr), info.first_bad_addr); | |
479 | pr_err("\n"); | |
480 | ||
481 | if (addr_has_shadow(untagged_addr)) { | |
482 | print_address_description(untagged_addr); | |
483 | pr_err("\n"); | |
484 | print_shadow_for_address(info.first_bad_addr); | |
485 | } else { | |
486 | dump_stack(); | |
487 | } | |
488 | ||
489 | end_report(&flags); | |
0b24becc | 490 | } |