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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 | |
7f0a84c2 AK |
135 | pr_err("BUG: KASAN: %s in %pS\n", |
136 | bug_type, (void *)info->ip); | |
137 | pr_err("%s of size %zu at addr %p by task %s/%d\n", | |
7d418f7b | 138 | info->is_write ? "Write" : "Read", info->access_size, |
7f0a84c2 | 139 | info->access_addr, 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 | ||
b6b72f49 | 180 | static void print_track(struct kasan_track *track, const char *prefix) |
7ed2f9e6 | 181 | { |
b6b72f49 | 182 | pr_err("%s by task %u:\n", prefix, track->pid); |
cd11016e AP |
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 | ||
db429f16 AK |
193 | static struct page *addr_to_page(const void *addr) |
194 | { | |
195 | if ((addr >= (void *)PAGE_OFFSET) && | |
196 | (addr < high_memory)) | |
197 | return virt_to_head_page(addr); | |
198 | return NULL; | |
199 | } | |
200 | ||
201 | static void describe_object(struct kmem_cache *cache, void *object) | |
7ed2f9e6 AP |
202 | { |
203 | struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); | |
7ed2f9e6 | 204 | |
47b5c2a0 AR |
205 | pr_err("Object at %p, in cache %s size: %d\n", object, cache->name, |
206 | cache->object_size); | |
207 | ||
7ed2f9e6 AP |
208 | if (!(cache->flags & SLAB_KASAN)) |
209 | return; | |
b3cbd9bf | 210 | |
b6b72f49 AK |
211 | print_track(&alloc_info->alloc_track, "Allocated"); |
212 | print_track(&alloc_info->free_track, "Freed"); | |
7ed2f9e6 | 213 | } |
7ed2f9e6 | 214 | |
7e088978 AR |
215 | void kasan_report_double_free(struct kmem_cache *cache, void *object, |
216 | s8 shadow) | |
217 | { | |
218 | unsigned long flags; | |
219 | ||
220 | kasan_start_report(&flags); | |
221 | pr_err("BUG: Double free or freeing an invalid pointer\n"); | |
222 | pr_err("Unexpected shadow byte: 0x%hhX\n", shadow); | |
db429f16 AK |
223 | dump_stack(); |
224 | describe_object(cache, object); | |
7e088978 AR |
225 | kasan_end_report(&flags); |
226 | } | |
227 | ||
0b24becc AR |
228 | static void print_address_description(struct kasan_access_info *info) |
229 | { | |
b8c73fc2 | 230 | const void *addr = info->access_addr; |
db429f16 | 231 | struct page *page = addr_to_page(addr); |
b8c73fc2 | 232 | |
db429f16 | 233 | if (page) |
b8c73fc2 | 234 | dump_page(page, "kasan: bad access detected"); |
db429f16 AK |
235 | |
236 | dump_stack(); | |
237 | ||
238 | if (page && PageSlab(page)) { | |
239 | struct kmem_cache *cache = page->slab_cache; | |
240 | void *object = nearest_obj(cache, page, (void *)addr); | |
241 | ||
242 | describe_object(cache, object); | |
b8c73fc2 AR |
243 | } |
244 | ||
bebf56a1 AR |
245 | if (kernel_or_module_addr(addr)) { |
246 | if (!init_task_stack_addr(addr)) | |
247 | pr_err("Address belongs to variable %pS\n", addr); | |
248 | } | |
0b24becc AR |
249 | } |
250 | ||
251 | static bool row_is_guilty(const void *row, const void *guilty) | |
252 | { | |
253 | return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); | |
254 | } | |
255 | ||
256 | static int shadow_pointer_offset(const void *row, const void *shadow) | |
257 | { | |
258 | /* The length of ">ff00ff00ff00ff00: " is | |
259 | * 3 + (BITS_PER_LONG/8)*2 chars. | |
260 | */ | |
261 | return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + | |
262 | (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; | |
263 | } | |
264 | ||
265 | static void print_shadow_for_address(const void *addr) | |
266 | { | |
267 | int i; | |
268 | const void *shadow = kasan_mem_to_shadow(addr); | |
269 | const void *shadow_row; | |
270 | ||
271 | shadow_row = (void *)round_down((unsigned long)shadow, | |
272 | SHADOW_BYTES_PER_ROW) | |
273 | - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; | |
274 | ||
275 | pr_err("Memory state around the buggy address:\n"); | |
276 | ||
277 | for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) { | |
278 | const void *kaddr = kasan_shadow_to_mem(shadow_row); | |
279 | char buffer[4 + (BITS_PER_LONG/8)*2]; | |
f2377d4e | 280 | char shadow_buf[SHADOW_BYTES_PER_ROW]; |
0b24becc AR |
281 | |
282 | snprintf(buffer, sizeof(buffer), | |
283 | (i == 0) ? ">%p: " : " %p: ", kaddr); | |
f2377d4e AK |
284 | /* |
285 | * We should not pass a shadow pointer to generic | |
286 | * function, because generic functions may try to | |
287 | * access kasan mapping for the passed address. | |
288 | */ | |
f2377d4e | 289 | memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW); |
0b24becc AR |
290 | print_hex_dump(KERN_ERR, buffer, |
291 | DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, | |
f2377d4e | 292 | shadow_buf, SHADOW_BYTES_PER_ROW, 0); |
0b24becc AR |
293 | |
294 | if (row_is_guilty(shadow_row, shadow)) | |
295 | pr_err("%*c\n", | |
296 | shadow_pointer_offset(shadow_row, shadow), | |
297 | '^'); | |
298 | ||
299 | shadow_row += SHADOW_BYTES_PER_ROW; | |
300 | } | |
301 | } | |
302 | ||
e9121076 | 303 | static void kasan_report_error(struct kasan_access_info *info) |
0b24becc AR |
304 | { |
305 | unsigned long flags; | |
306 | ||
7e088978 AR |
307 | kasan_start_report(&flags); |
308 | ||
7d418f7b AK |
309 | print_error_description(info); |
310 | ||
5e82cd12 | 311 | if (!addr_has_shadow(info)) { |
e9121076 AK |
312 | dump_stack(); |
313 | } else { | |
e9121076 AK |
314 | print_address_description(info); |
315 | print_shadow_for_address(info->first_bad_addr); | |
316 | } | |
7e088978 AR |
317 | |
318 | kasan_end_report(&flags); | |
0b24becc AR |
319 | } |
320 | ||
b0845ce5 MR |
321 | static unsigned long kasan_flags; |
322 | ||
323 | #define KASAN_BIT_REPORTED 0 | |
324 | #define KASAN_BIT_MULTI_SHOT 1 | |
325 | ||
326 | bool kasan_save_enable_multi_shot(void) | |
327 | { | |
328 | return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); | |
329 | } | |
330 | EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot); | |
331 | ||
332 | void kasan_restore_multi_shot(bool enabled) | |
333 | { | |
334 | if (!enabled) | |
335 | clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); | |
336 | } | |
337 | EXPORT_SYMBOL_GPL(kasan_restore_multi_shot); | |
338 | ||
339 | static int __init kasan_set_multi_shot(char *str) | |
340 | { | |
341 | set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); | |
342 | return 1; | |
343 | } | |
344 | __setup("kasan_multi_shot", kasan_set_multi_shot); | |
345 | ||
346 | static inline bool kasan_report_enabled(void) | |
347 | { | |
348 | if (current->kasan_depth) | |
349 | return false; | |
350 | if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) | |
351 | return true; | |
352 | return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); | |
353 | } | |
354 | ||
0b24becc AR |
355 | void kasan_report(unsigned long addr, size_t size, |
356 | bool is_write, unsigned long ip) | |
357 | { | |
358 | struct kasan_access_info info; | |
359 | ||
0ba8663c | 360 | if (likely(!kasan_report_enabled())) |
0b24becc AR |
361 | return; |
362 | ||
4f40c6e5 PZ |
363 | disable_trace_on_warning(); |
364 | ||
0b24becc AR |
365 | info.access_addr = (void *)addr; |
366 | info.access_size = size; | |
367 | info.is_write = is_write; | |
368 | info.ip = ip; | |
e9121076 | 369 | |
0b24becc AR |
370 | kasan_report_error(&info); |
371 | } | |
372 | ||
373 | ||
374 | #define DEFINE_ASAN_REPORT_LOAD(size) \ | |
375 | void __asan_report_load##size##_noabort(unsigned long addr) \ | |
376 | { \ | |
377 | kasan_report(addr, size, false, _RET_IP_); \ | |
378 | } \ | |
379 | EXPORT_SYMBOL(__asan_report_load##size##_noabort) | |
380 | ||
381 | #define DEFINE_ASAN_REPORT_STORE(size) \ | |
382 | void __asan_report_store##size##_noabort(unsigned long addr) \ | |
383 | { \ | |
384 | kasan_report(addr, size, true, _RET_IP_); \ | |
385 | } \ | |
386 | EXPORT_SYMBOL(__asan_report_store##size##_noabort) | |
387 | ||
388 | DEFINE_ASAN_REPORT_LOAD(1); | |
389 | DEFINE_ASAN_REPORT_LOAD(2); | |
390 | DEFINE_ASAN_REPORT_LOAD(4); | |
391 | DEFINE_ASAN_REPORT_LOAD(8); | |
392 | DEFINE_ASAN_REPORT_LOAD(16); | |
393 | DEFINE_ASAN_REPORT_STORE(1); | |
394 | DEFINE_ASAN_REPORT_STORE(2); | |
395 | DEFINE_ASAN_REPORT_STORE(4); | |
396 | DEFINE_ASAN_REPORT_STORE(8); | |
397 | DEFINE_ASAN_REPORT_STORE(16); | |
398 | ||
399 | void __asan_report_load_n_noabort(unsigned long addr, size_t size) | |
400 | { | |
401 | kasan_report(addr, size, false, _RET_IP_); | |
402 | } | |
403 | EXPORT_SYMBOL(__asan_report_load_n_noabort); | |
404 | ||
405 | void __asan_report_store_n_noabort(unsigned long addr, size_t size) | |
406 | { | |
407 | kasan_report(addr, size, true, _RET_IP_); | |
408 | } | |
409 | EXPORT_SYMBOL(__asan_report_store_n_noabort); |