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Commit | Line | Data |
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0b24becc AR |
1 | /* |
2 | * This file contains error reporting code. | |
3 | * | |
4 | * Copyright (c) 2014 Samsung Electronics Co., Ltd. | |
2baf9e89 | 5 | * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> |
0b24becc | 6 | * |
5d0926ef | 7 | * Some code borrowed from https://github.com/xairy/kasan-prototype by |
0b24becc AR |
8 | * Andrey Konovalov <adech.fo@gmail.com> |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify | |
11 | * it under the terms of the GNU General Public License version 2 as | |
12 | * published by the Free Software Foundation. | |
13 | * | |
14 | */ | |
15 | ||
b0845ce5 | 16 | #include <linux/bitops.h> |
4f40c6e5 | 17 | #include <linux/ftrace.h> |
b0845ce5 | 18 | #include <linux/init.h> |
0b24becc AR |
19 | #include <linux/kernel.h> |
20 | #include <linux/mm.h> | |
21 | #include <linux/printk.h> | |
22 | #include <linux/sched.h> | |
23 | #include <linux/slab.h> | |
cd11016e | 24 | #include <linux/stackdepot.h> |
0b24becc AR |
25 | #include <linux/stacktrace.h> |
26 | #include <linux/string.h> | |
27 | #include <linux/types.h> | |
28 | #include <linux/kasan.h> | |
527f215b | 29 | #include <linux/module.h> |
0b24becc | 30 | |
bebf56a1 AR |
31 | #include <asm/sections.h> |
32 | ||
0b24becc | 33 | #include "kasan.h" |
0316bec2 | 34 | #include "../slab.h" |
0b24becc AR |
35 | |
36 | /* Shadow layout customization. */ | |
37 | #define SHADOW_BYTES_PER_BLOCK 1 | |
38 | #define SHADOW_BLOCKS_PER_ROW 16 | |
39 | #define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK) | |
40 | #define SHADOW_ROWS_AROUND_ADDR 2 | |
41 | ||
42 | static const void *find_first_bad_addr(const void *addr, size_t size) | |
43 | { | |
44 | u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr); | |
45 | const void *first_bad_addr = addr; | |
46 | ||
47 | while (!shadow_val && first_bad_addr < addr + size) { | |
48 | first_bad_addr += KASAN_SHADOW_SCALE_SIZE; | |
49 | shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr); | |
50 | } | |
51 | return first_bad_addr; | |
52 | } | |
53 | ||
5e82cd12 AK |
54 | static bool addr_has_shadow(struct kasan_access_info *info) |
55 | { | |
56 | return (info->access_addr >= | |
57 | kasan_shadow_to_mem((void *)KASAN_SHADOW_START)); | |
58 | } | |
59 | ||
60 | static const char *get_shadow_bug_type(struct kasan_access_info *info) | |
0b24becc | 61 | { |
0952d87f | 62 | const char *bug_type = "unknown-crash"; |
cdf6a273 | 63 | u8 *shadow_addr; |
0b24becc AR |
64 | |
65 | info->first_bad_addr = find_first_bad_addr(info->access_addr, | |
66 | info->access_size); | |
67 | ||
cdf6a273 | 68 | shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr); |
0b24becc | 69 | |
cdf6a273 AK |
70 | /* |
71 | * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look | |
72 | * at the next shadow byte to determine the type of the bad access. | |
73 | */ | |
74 | if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1) | |
75 | shadow_addr++; | |
76 | ||
77 | switch (*shadow_addr) { | |
0952d87f | 78 | case 0 ... KASAN_SHADOW_SCALE_SIZE - 1: |
cdf6a273 AK |
79 | /* |
80 | * In theory it's still possible to see these shadow values | |
81 | * due to a data race in the kernel code. | |
82 | */ | |
0952d87f | 83 | bug_type = "out-of-bounds"; |
b8c73fc2 | 84 | break; |
0316bec2 AR |
85 | case KASAN_PAGE_REDZONE: |
86 | case KASAN_KMALLOC_REDZONE: | |
0952d87f AK |
87 | bug_type = "slab-out-of-bounds"; |
88 | break; | |
bebf56a1 | 89 | case KASAN_GLOBAL_REDZONE: |
0952d87f | 90 | bug_type = "global-out-of-bounds"; |
0b24becc | 91 | break; |
c420f167 AR |
92 | case KASAN_STACK_LEFT: |
93 | case KASAN_STACK_MID: | |
94 | case KASAN_STACK_RIGHT: | |
95 | case KASAN_STACK_PARTIAL: | |
0952d87f AK |
96 | bug_type = "stack-out-of-bounds"; |
97 | break; | |
98 | case KASAN_FREE_PAGE: | |
99 | case KASAN_KMALLOC_FREE: | |
100 | bug_type = "use-after-free"; | |
c420f167 | 101 | break; |
828347f8 DV |
102 | case KASAN_USE_AFTER_SCOPE: |
103 | bug_type = "use-after-scope"; | |
104 | break; | |
0b24becc AR |
105 | } |
106 | ||
5e82cd12 AK |
107 | return bug_type; |
108 | } | |
109 | ||
110 | const char *get_wild_bug_type(struct kasan_access_info *info) | |
111 | { | |
112 | const char *bug_type = "unknown-crash"; | |
113 | ||
114 | if ((unsigned long)info->access_addr < PAGE_SIZE) | |
115 | bug_type = "null-ptr-deref"; | |
116 | else if ((unsigned long)info->access_addr < TASK_SIZE) | |
117 | bug_type = "user-memory-access"; | |
118 | else | |
119 | bug_type = "wild-memory-access"; | |
120 | ||
121 | return bug_type; | |
122 | } | |
123 | ||
7d418f7b AK |
124 | static const char *get_bug_type(struct kasan_access_info *info) |
125 | { | |
126 | if (addr_has_shadow(info)) | |
127 | return get_shadow_bug_type(info); | |
128 | return get_wild_bug_type(info); | |
129 | } | |
130 | ||
5e82cd12 AK |
131 | static void print_error_description(struct kasan_access_info *info) |
132 | { | |
7d418f7b | 133 | const char *bug_type = get_bug_type(info); |
5e82cd12 | 134 | |
25add7ec | 135 | pr_err("BUG: KASAN: %s in %pS at addr %p\n", |
7d418f7b | 136 | bug_type, (void *)info->ip, info->access_addr); |
0b24becc | 137 | pr_err("%s of size %zu by task %s/%d\n", |
7d418f7b AK |
138 | info->is_write ? "Write" : "Read", info->access_size, |
139 | current->comm, task_pid_nr(current)); | |
0b24becc AR |
140 | } |
141 | ||
bebf56a1 AR |
142 | static inline bool kernel_or_module_addr(const void *addr) |
143 | { | |
527f215b AK |
144 | if (addr >= (void *)_stext && addr < (void *)_end) |
145 | return true; | |
146 | if (is_module_address((unsigned long)addr)) | |
147 | return true; | |
148 | return false; | |
bebf56a1 AR |
149 | } |
150 | ||
151 | static inline bool init_task_stack_addr(const void *addr) | |
152 | { | |
153 | return addr >= (void *)&init_thread_union.stack && | |
154 | (addr <= (void *)&init_thread_union.stack + | |
155 | sizeof(init_thread_union.stack)); | |
156 | } | |
157 | ||
7e088978 AR |
158 | static DEFINE_SPINLOCK(report_lock); |
159 | ||
160 | static void kasan_start_report(unsigned long *flags) | |
161 | { | |
162 | /* | |
163 | * Make sure we don't end up in loop. | |
164 | */ | |
165 | kasan_disable_current(); | |
166 | spin_lock_irqsave(&report_lock, *flags); | |
167 | pr_err("==================================================================\n"); | |
168 | } | |
169 | ||
170 | static void kasan_end_report(unsigned long *flags) | |
171 | { | |
172 | pr_err("==================================================================\n"); | |
173 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); | |
174 | spin_unlock_irqrestore(&report_lock, *flags); | |
5c5c1f36 DV |
175 | if (panic_on_warn) |
176 | panic("panic_on_warn set ...\n"); | |
7e088978 AR |
177 | kasan_enable_current(); |
178 | } | |
179 | ||
7ed2f9e6 AP |
180 | static void print_track(struct kasan_track *track) |
181 | { | |
cd11016e AP |
182 | pr_err("PID = %u\n", track->pid); |
183 | if (track->stack) { | |
184 | struct stack_trace trace; | |
185 | ||
186 | depot_fetch_stack(track->stack, &trace); | |
187 | print_stack_trace(&trace, 0); | |
188 | } else { | |
189 | pr_err("(stack is not available)\n"); | |
190 | } | |
7ed2f9e6 AP |
191 | } |
192 | ||
7e088978 | 193 | static void kasan_object_err(struct kmem_cache *cache, void *object) |
7ed2f9e6 AP |
194 | { |
195 | struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); | |
7ed2f9e6 AP |
196 | |
197 | dump_stack(); | |
47b5c2a0 AR |
198 | pr_err("Object at %p, in cache %s size: %d\n", object, cache->name, |
199 | cache->object_size); | |
200 | ||
7ed2f9e6 AP |
201 | if (!(cache->flags & SLAB_KASAN)) |
202 | return; | |
b3cbd9bf AR |
203 | |
204 | pr_err("Allocated:\n"); | |
205 | print_track(&alloc_info->alloc_track); | |
206 | pr_err("Freed:\n"); | |
207 | print_track(&alloc_info->free_track); | |
7ed2f9e6 | 208 | } |
7ed2f9e6 | 209 | |
7e088978 AR |
210 | void kasan_report_double_free(struct kmem_cache *cache, void *object, |
211 | s8 shadow) | |
212 | { | |
213 | unsigned long flags; | |
214 | ||
215 | kasan_start_report(&flags); | |
216 | pr_err("BUG: Double free or freeing an invalid pointer\n"); | |
217 | pr_err("Unexpected shadow byte: 0x%hhX\n", shadow); | |
218 | kasan_object_err(cache, object); | |
219 | kasan_end_report(&flags); | |
220 | } | |
221 | ||
0b24becc AR |
222 | static void print_address_description(struct kasan_access_info *info) |
223 | { | |
b8c73fc2 AR |
224 | const void *addr = info->access_addr; |
225 | ||
226 | if ((addr >= (void *)PAGE_OFFSET) && | |
227 | (addr < high_memory)) { | |
228 | struct page *page = virt_to_head_page(addr); | |
0316bec2 AR |
229 | |
230 | if (PageSlab(page)) { | |
231 | void *object; | |
232 | struct kmem_cache *cache = page->slab_cache; | |
7ed2f9e6 AP |
233 | object = nearest_obj(cache, page, |
234 | (void *)info->access_addr); | |
7e088978 | 235 | kasan_object_err(cache, object); |
0316bec2 AR |
236 | return; |
237 | } | |
b8c73fc2 AR |
238 | dump_page(page, "kasan: bad access detected"); |
239 | } | |
240 | ||
bebf56a1 AR |
241 | if (kernel_or_module_addr(addr)) { |
242 | if (!init_task_stack_addr(addr)) | |
243 | pr_err("Address belongs to variable %pS\n", addr); | |
244 | } | |
0b24becc AR |
245 | dump_stack(); |
246 | } | |
247 | ||
248 | static bool row_is_guilty(const void *row, const void *guilty) | |
249 | { | |
250 | return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); | |
251 | } | |
252 | ||
253 | static int shadow_pointer_offset(const void *row, const void *shadow) | |
254 | { | |
255 | /* The length of ">ff00ff00ff00ff00: " is | |
256 | * 3 + (BITS_PER_LONG/8)*2 chars. | |
257 | */ | |
258 | return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + | |
259 | (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; | |
260 | } | |
261 | ||
262 | static void print_shadow_for_address(const void *addr) | |
263 | { | |
264 | int i; | |
265 | const void *shadow = kasan_mem_to_shadow(addr); | |
266 | const void *shadow_row; | |
267 | ||
268 | shadow_row = (void *)round_down((unsigned long)shadow, | |
269 | SHADOW_BYTES_PER_ROW) | |
270 | - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; | |
271 | ||
272 | pr_err("Memory state around the buggy address:\n"); | |
273 | ||
274 | for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) { | |
275 | const void *kaddr = kasan_shadow_to_mem(shadow_row); | |
276 | char buffer[4 + (BITS_PER_LONG/8)*2]; | |
f2377d4e | 277 | char shadow_buf[SHADOW_BYTES_PER_ROW]; |
0b24becc AR |
278 | |
279 | snprintf(buffer, sizeof(buffer), | |
280 | (i == 0) ? ">%p: " : " %p: ", kaddr); | |
f2377d4e AK |
281 | /* |
282 | * We should not pass a shadow pointer to generic | |
283 | * function, because generic functions may try to | |
284 | * access kasan mapping for the passed address. | |
285 | */ | |
f2377d4e | 286 | memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW); |
0b24becc AR |
287 | print_hex_dump(KERN_ERR, buffer, |
288 | DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, | |
f2377d4e | 289 | shadow_buf, SHADOW_BYTES_PER_ROW, 0); |
0b24becc AR |
290 | |
291 | if (row_is_guilty(shadow_row, shadow)) | |
292 | pr_err("%*c\n", | |
293 | shadow_pointer_offset(shadow_row, shadow), | |
294 | '^'); | |
295 | ||
296 | shadow_row += SHADOW_BYTES_PER_ROW; | |
297 | } | |
298 | } | |
299 | ||
e9121076 | 300 | static void kasan_report_error(struct kasan_access_info *info) |
0b24becc AR |
301 | { |
302 | unsigned long flags; | |
303 | ||
7e088978 AR |
304 | kasan_start_report(&flags); |
305 | ||
7d418f7b AK |
306 | print_error_description(info); |
307 | ||
5e82cd12 | 308 | if (!addr_has_shadow(info)) { |
e9121076 AK |
309 | dump_stack(); |
310 | } else { | |
e9121076 AK |
311 | print_address_description(info); |
312 | print_shadow_for_address(info->first_bad_addr); | |
313 | } | |
7e088978 AR |
314 | |
315 | kasan_end_report(&flags); | |
0b24becc AR |
316 | } |
317 | ||
b0845ce5 MR |
318 | static unsigned long kasan_flags; |
319 | ||
320 | #define KASAN_BIT_REPORTED 0 | |
321 | #define KASAN_BIT_MULTI_SHOT 1 | |
322 | ||
323 | bool kasan_save_enable_multi_shot(void) | |
324 | { | |
325 | return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); | |
326 | } | |
327 | EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot); | |
328 | ||
329 | void kasan_restore_multi_shot(bool enabled) | |
330 | { | |
331 | if (!enabled) | |
332 | clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); | |
333 | } | |
334 | EXPORT_SYMBOL_GPL(kasan_restore_multi_shot); | |
335 | ||
336 | static int __init kasan_set_multi_shot(char *str) | |
337 | { | |
338 | set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); | |
339 | return 1; | |
340 | } | |
341 | __setup("kasan_multi_shot", kasan_set_multi_shot); | |
342 | ||
343 | static inline bool kasan_report_enabled(void) | |
344 | { | |
345 | if (current->kasan_depth) | |
346 | return false; | |
347 | if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) | |
348 | return true; | |
349 | return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); | |
350 | } | |
351 | ||
0b24becc AR |
352 | void kasan_report(unsigned long addr, size_t size, |
353 | bool is_write, unsigned long ip) | |
354 | { | |
355 | struct kasan_access_info info; | |
356 | ||
0ba8663c | 357 | if (likely(!kasan_report_enabled())) |
0b24becc AR |
358 | return; |
359 | ||
4f40c6e5 PZ |
360 | disable_trace_on_warning(); |
361 | ||
0b24becc AR |
362 | info.access_addr = (void *)addr; |
363 | info.access_size = size; | |
364 | info.is_write = is_write; | |
365 | info.ip = ip; | |
e9121076 | 366 | |
0b24becc AR |
367 | kasan_report_error(&info); |
368 | } | |
369 | ||
370 | ||
371 | #define DEFINE_ASAN_REPORT_LOAD(size) \ | |
372 | void __asan_report_load##size##_noabort(unsigned long addr) \ | |
373 | { \ | |
374 | kasan_report(addr, size, false, _RET_IP_); \ | |
375 | } \ | |
376 | EXPORT_SYMBOL(__asan_report_load##size##_noabort) | |
377 | ||
378 | #define DEFINE_ASAN_REPORT_STORE(size) \ | |
379 | void __asan_report_store##size##_noabort(unsigned long addr) \ | |
380 | { \ | |
381 | kasan_report(addr, size, true, _RET_IP_); \ | |
382 | } \ | |
383 | EXPORT_SYMBOL(__asan_report_store##size##_noabort) | |
384 | ||
385 | DEFINE_ASAN_REPORT_LOAD(1); | |
386 | DEFINE_ASAN_REPORT_LOAD(2); | |
387 | DEFINE_ASAN_REPORT_LOAD(4); | |
388 | DEFINE_ASAN_REPORT_LOAD(8); | |
389 | DEFINE_ASAN_REPORT_LOAD(16); | |
390 | DEFINE_ASAN_REPORT_STORE(1); | |
391 | DEFINE_ASAN_REPORT_STORE(2); | |
392 | DEFINE_ASAN_REPORT_STORE(4); | |
393 | DEFINE_ASAN_REPORT_STORE(8); | |
394 | DEFINE_ASAN_REPORT_STORE(16); | |
395 | ||
396 | void __asan_report_load_n_noabort(unsigned long addr, size_t size) | |
397 | { | |
398 | kasan_report(addr, size, false, _RET_IP_); | |
399 | } | |
400 | EXPORT_SYMBOL(__asan_report_load_n_noabort); | |
401 | ||
402 | void __asan_report_store_n_noabort(unsigned long addr, size_t size) | |
403 | { | |
404 | kasan_report(addr, size, true, _RET_IP_); | |
405 | } | |
406 | EXPORT_SYMBOL(__asan_report_store_n_noabort); |