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 | const void *kasan_find_first_bad_addr(const void *addr, size_t size) |
34 | { |
35 | const void *p = addr; |
36 | |
37 | if (!addr_has_metadata(addr: 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 | 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 | |
74 | static const char *get_shadow_bug_type(struct kasan_report_info *info) |
75 | { |
76 | const char *bug_type = "unknown-crash" ; |
77 | u8 *shadow_addr; |
78 | |
79 | shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr); |
80 | |
81 | /* |
82 | * If shadow byte value is in [0, KASAN_GRANULE_SIZE) we can look |
83 | * at the next shadow byte to determine the type of the bad access. |
84 | */ |
85 | if (*shadow_addr > 0 && *shadow_addr <= KASAN_GRANULE_SIZE - 1) |
86 | shadow_addr++; |
87 | |
88 | switch (*shadow_addr) { |
89 | case 0 ... KASAN_GRANULE_SIZE - 1: |
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: |
97 | case KASAN_SLAB_REDZONE: |
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; |
109 | case KASAN_PAGE_FREE: |
110 | bug_type = "use-after-free" ; |
111 | break; |
112 | case KASAN_SLAB_FREE: |
113 | case KASAN_SLAB_FREE_META: |
114 | bug_type = "slab-use-after-free" ; |
115 | break; |
116 | case KASAN_ALLOCA_LEFT: |
117 | case KASAN_ALLOCA_RIGHT: |
118 | bug_type = "alloca-out-of-bounds" ; |
119 | break; |
120 | case KASAN_VMALLOC_INVALID: |
121 | bug_type = "vmalloc-out-of-bounds" ; |
122 | break; |
123 | } |
124 | |
125 | return bug_type; |
126 | } |
127 | |
128 | static const char *get_wild_bug_type(struct kasan_report_info *info) |
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 | |
142 | static const char *get_bug_type(struct kasan_report_info *info) |
143 | { |
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 | |
155 | if (addr_has_metadata(addr: info->access_addr)) |
156 | return get_shadow_bug_type(info); |
157 | return get_wild_bug_type(info); |
158 | } |
159 | |
160 | void kasan_complete_mode_report_info(struct kasan_report_info *info) |
161 | { |
162 | struct kasan_alloc_meta *alloc_meta; |
163 | struct kasan_free_meta *free_meta; |
164 | |
165 | if (!info->bug_type) |
166 | info->bug_type = get_bug_type(info); |
167 | |
168 | if (!info->cache || !info->object) |
169 | return; |
170 | |
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_FREE_META) { |
177 | /* Free meta must be present with KASAN_SLAB_FREE_META. */ |
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 | } |
182 | } |
183 | |
184 | void kasan_metadata_fetch_row(char *buffer, void *row) |
185 | { |
186 | memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW); |
187 | } |
188 | |
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(stack: 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(stack: alloc_meta->aux_stack[1]); |
205 | pr_err("\n" ); |
206 | } |
207 | } |
208 | |
209 | #ifdef CONFIG_KASAN_STACK |
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("internal error: frame description too long: %s\n" , |
224 | *frame_descr); |
225 | return false; |
226 | } |
227 | |
228 | /* Copy token (+ 1 byte for '\0'). */ |
229 | strscpy(token, *frame_descr, tok_len + 1); |
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("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" ); |
261 | pr_err("This frame has %lu %s:\n" , num_objects, |
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 | |
292 | /* Returns true only if the address is on the current task's stack. */ |
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 | |
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("internal error: frame has 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 | |
338 | void kasan_print_address_stack_frame(const void *addr) |
339 | { |
340 | unsigned long offset; |
341 | const char *frame_descr; |
342 | const void *frame_pc; |
343 | |
344 | if (WARN_ON(!object_is_on_stack(addr))) |
345 | return; |
346 | |
347 | pr_err("The buggy address belongs to stack of task %s/%d\n" , |
348 | current->comm, task_pid_nr(current)); |
349 | |
350 | if (!get_address_stack_frame_info(addr, &offset, &frame_descr, |
351 | &frame_pc)) |
352 | return; |
353 | |
354 | pr_err(" and is located at offset %lu in frame:\n" , offset); |
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 | |
364 | #define DEFINE_ASAN_REPORT_LOAD(size) \ |
365 | void __asan_report_load##size##_noabort(void *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(void *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(void *addr, ssize_t size) |
390 | { |
391 | kasan_report(addr, size, is_write: false, _RET_IP_); |
392 | } |
393 | EXPORT_SYMBOL(__asan_report_load_n_noabort); |
394 | |
395 | void __asan_report_store_n_noabort(void *addr, ssize_t size) |
396 | { |
397 | kasan_report(addr, size, is_write: true, _RET_IP_); |
398 | } |
399 | EXPORT_SYMBOL(__asan_report_store_n_noabort); |
400 | |