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