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 | ||
16 | #include <linux/kernel.h> | |
17 | #include <linux/mm.h> | |
18 | #include <linux/printk.h> | |
19 | #include <linux/sched.h> | |
20 | #include <linux/slab.h> | |
21 | #include <linux/stacktrace.h> | |
22 | #include <linux/string.h> | |
23 | #include <linux/types.h> | |
24 | #include <linux/kasan.h> | |
527f215b | 25 | #include <linux/module.h> |
0b24becc | 26 | |
bebf56a1 AR |
27 | #include <asm/sections.h> |
28 | ||
0b24becc | 29 | #include "kasan.h" |
0316bec2 | 30 | #include "../slab.h" |
0b24becc AR |
31 | |
32 | /* Shadow layout customization. */ | |
33 | #define SHADOW_BYTES_PER_BLOCK 1 | |
34 | #define SHADOW_BLOCKS_PER_ROW 16 | |
35 | #define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK) | |
36 | #define SHADOW_ROWS_AROUND_ADDR 2 | |
37 | ||
38 | static const void *find_first_bad_addr(const void *addr, size_t size) | |
39 | { | |
40 | u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr); | |
41 | const void *first_bad_addr = addr; | |
42 | ||
43 | while (!shadow_val && first_bad_addr < addr + size) { | |
44 | first_bad_addr += KASAN_SHADOW_SCALE_SIZE; | |
45 | shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr); | |
46 | } | |
47 | return first_bad_addr; | |
48 | } | |
49 | ||
50 | static void print_error_description(struct kasan_access_info *info) | |
51 | { | |
0952d87f | 52 | const char *bug_type = "unknown-crash"; |
cdf6a273 | 53 | u8 *shadow_addr; |
0b24becc AR |
54 | |
55 | info->first_bad_addr = find_first_bad_addr(info->access_addr, | |
56 | info->access_size); | |
57 | ||
cdf6a273 | 58 | shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr); |
0b24becc | 59 | |
cdf6a273 AK |
60 | /* |
61 | * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look | |
62 | * at the next shadow byte to determine the type of the bad access. | |
63 | */ | |
64 | if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1) | |
65 | shadow_addr++; | |
66 | ||
67 | switch (*shadow_addr) { | |
0952d87f | 68 | case 0 ... KASAN_SHADOW_SCALE_SIZE - 1: |
cdf6a273 AK |
69 | /* |
70 | * In theory it's still possible to see these shadow values | |
71 | * due to a data race in the kernel code. | |
72 | */ | |
0952d87f | 73 | bug_type = "out-of-bounds"; |
b8c73fc2 | 74 | break; |
0316bec2 AR |
75 | case KASAN_PAGE_REDZONE: |
76 | case KASAN_KMALLOC_REDZONE: | |
0952d87f AK |
77 | bug_type = "slab-out-of-bounds"; |
78 | break; | |
bebf56a1 | 79 | case KASAN_GLOBAL_REDZONE: |
0952d87f | 80 | bug_type = "global-out-of-bounds"; |
0b24becc | 81 | break; |
c420f167 AR |
82 | case KASAN_STACK_LEFT: |
83 | case KASAN_STACK_MID: | |
84 | case KASAN_STACK_RIGHT: | |
85 | case KASAN_STACK_PARTIAL: | |
0952d87f AK |
86 | bug_type = "stack-out-of-bounds"; |
87 | break; | |
88 | case KASAN_FREE_PAGE: | |
89 | case KASAN_KMALLOC_FREE: | |
90 | bug_type = "use-after-free"; | |
c420f167 | 91 | break; |
0b24becc AR |
92 | } |
93 | ||
25add7ec | 94 | pr_err("BUG: KASAN: %s in %pS at addr %p\n", |
0b24becc AR |
95 | bug_type, (void *)info->ip, |
96 | info->access_addr); | |
97 | pr_err("%s of size %zu by task %s/%d\n", | |
98 | info->is_write ? "Write" : "Read", | |
99 | info->access_size, current->comm, task_pid_nr(current)); | |
100 | } | |
101 | ||
bebf56a1 AR |
102 | static inline bool kernel_or_module_addr(const void *addr) |
103 | { | |
527f215b AK |
104 | if (addr >= (void *)_stext && addr < (void *)_end) |
105 | return true; | |
106 | if (is_module_address((unsigned long)addr)) | |
107 | return true; | |
108 | return false; | |
bebf56a1 AR |
109 | } |
110 | ||
111 | static inline bool init_task_stack_addr(const void *addr) | |
112 | { | |
113 | return addr >= (void *)&init_thread_union.stack && | |
114 | (addr <= (void *)&init_thread_union.stack + | |
115 | sizeof(init_thread_union.stack)); | |
116 | } | |
117 | ||
7ed2f9e6 AP |
118 | #ifdef CONFIG_SLAB |
119 | static void print_track(struct kasan_track *track) | |
120 | { | |
121 | pr_err("PID = %u, CPU = %u, timestamp = %lu\n", track->pid, | |
122 | track->cpu, (unsigned long)track->when); | |
123 | } | |
124 | ||
125 | static void object_err(struct kmem_cache *cache, struct page *page, | |
126 | void *object, char *unused_reason) | |
127 | { | |
128 | struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); | |
129 | struct kasan_free_meta *free_info; | |
130 | ||
131 | dump_stack(); | |
132 | pr_err("Object at %p, in cache %s\n", object, cache->name); | |
133 | if (!(cache->flags & SLAB_KASAN)) | |
134 | return; | |
135 | switch (alloc_info->state) { | |
136 | case KASAN_STATE_INIT: | |
137 | pr_err("Object not allocated yet\n"); | |
138 | break; | |
139 | case KASAN_STATE_ALLOC: | |
140 | pr_err("Object allocated with size %u bytes.\n", | |
141 | alloc_info->alloc_size); | |
142 | pr_err("Allocation:\n"); | |
143 | print_track(&alloc_info->track); | |
144 | break; | |
145 | case KASAN_STATE_FREE: | |
146 | pr_err("Object freed, allocated with size %u bytes\n", | |
147 | alloc_info->alloc_size); | |
148 | free_info = get_free_info(cache, object); | |
149 | pr_err("Allocation:\n"); | |
150 | print_track(&alloc_info->track); | |
151 | pr_err("Deallocation:\n"); | |
152 | print_track(&free_info->track); | |
153 | break; | |
154 | } | |
155 | } | |
156 | #endif | |
157 | ||
0b24becc AR |
158 | static void print_address_description(struct kasan_access_info *info) |
159 | { | |
b8c73fc2 AR |
160 | const void *addr = info->access_addr; |
161 | ||
162 | if ((addr >= (void *)PAGE_OFFSET) && | |
163 | (addr < high_memory)) { | |
164 | struct page *page = virt_to_head_page(addr); | |
0316bec2 AR |
165 | |
166 | if (PageSlab(page)) { | |
167 | void *object; | |
168 | struct kmem_cache *cache = page->slab_cache; | |
7ed2f9e6 AP |
169 | object = nearest_obj(cache, page, |
170 | (void *)info->access_addr); | |
0316bec2 | 171 | object_err(cache, page, object, |
7ed2f9e6 | 172 | "kasan: bad access detected"); |
0316bec2 AR |
173 | return; |
174 | } | |
b8c73fc2 AR |
175 | dump_page(page, "kasan: bad access detected"); |
176 | } | |
177 | ||
bebf56a1 AR |
178 | if (kernel_or_module_addr(addr)) { |
179 | if (!init_task_stack_addr(addr)) | |
180 | pr_err("Address belongs to variable %pS\n", addr); | |
181 | } | |
0b24becc AR |
182 | dump_stack(); |
183 | } | |
184 | ||
185 | static bool row_is_guilty(const void *row, const void *guilty) | |
186 | { | |
187 | return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); | |
188 | } | |
189 | ||
190 | static int shadow_pointer_offset(const void *row, const void *shadow) | |
191 | { | |
192 | /* The length of ">ff00ff00ff00ff00: " is | |
193 | * 3 + (BITS_PER_LONG/8)*2 chars. | |
194 | */ | |
195 | return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + | |
196 | (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; | |
197 | } | |
198 | ||
199 | static void print_shadow_for_address(const void *addr) | |
200 | { | |
201 | int i; | |
202 | const void *shadow = kasan_mem_to_shadow(addr); | |
203 | const void *shadow_row; | |
204 | ||
205 | shadow_row = (void *)round_down((unsigned long)shadow, | |
206 | SHADOW_BYTES_PER_ROW) | |
207 | - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; | |
208 | ||
209 | pr_err("Memory state around the buggy address:\n"); | |
210 | ||
211 | for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) { | |
212 | const void *kaddr = kasan_shadow_to_mem(shadow_row); | |
213 | char buffer[4 + (BITS_PER_LONG/8)*2]; | |
f2377d4e | 214 | char shadow_buf[SHADOW_BYTES_PER_ROW]; |
0b24becc AR |
215 | |
216 | snprintf(buffer, sizeof(buffer), | |
217 | (i == 0) ? ">%p: " : " %p: ", kaddr); | |
f2377d4e AK |
218 | /* |
219 | * We should not pass a shadow pointer to generic | |
220 | * function, because generic functions may try to | |
221 | * access kasan mapping for the passed address. | |
222 | */ | |
f2377d4e | 223 | memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW); |
0b24becc AR |
224 | print_hex_dump(KERN_ERR, buffer, |
225 | DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, | |
f2377d4e | 226 | shadow_buf, SHADOW_BYTES_PER_ROW, 0); |
0b24becc AR |
227 | |
228 | if (row_is_guilty(shadow_row, shadow)) | |
229 | pr_err("%*c\n", | |
230 | shadow_pointer_offset(shadow_row, shadow), | |
231 | '^'); | |
232 | ||
233 | shadow_row += SHADOW_BYTES_PER_ROW; | |
234 | } | |
235 | } | |
236 | ||
237 | static DEFINE_SPINLOCK(report_lock); | |
238 | ||
e9121076 | 239 | static void kasan_report_error(struct kasan_access_info *info) |
0b24becc AR |
240 | { |
241 | unsigned long flags; | |
e9121076 | 242 | const char *bug_type; |
0b24becc | 243 | |
fc5aeeaf AK |
244 | /* |
245 | * Make sure we don't end up in loop. | |
246 | */ | |
247 | kasan_disable_current(); | |
0b24becc | 248 | spin_lock_irqsave(&report_lock, flags); |
756a025f | 249 | pr_err("==================================================================\n"); |
e9121076 AK |
250 | if (info->access_addr < |
251 | kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) { | |
252 | if ((unsigned long)info->access_addr < PAGE_SIZE) | |
253 | bug_type = "null-ptr-deref"; | |
254 | else if ((unsigned long)info->access_addr < TASK_SIZE) | |
255 | bug_type = "user-memory-access"; | |
256 | else | |
257 | bug_type = "wild-memory-access"; | |
25add7ec | 258 | pr_err("BUG: KASAN: %s on address %p\n", |
e9121076 AK |
259 | bug_type, info->access_addr); |
260 | pr_err("%s of size %zu by task %s/%d\n", | |
261 | info->is_write ? "Write" : "Read", | |
262 | info->access_size, current->comm, | |
263 | task_pid_nr(current)); | |
264 | dump_stack(); | |
265 | } else { | |
266 | print_error_description(info); | |
267 | print_address_description(info); | |
268 | print_shadow_for_address(info->first_bad_addr); | |
269 | } | |
756a025f | 270 | pr_err("==================================================================\n"); |
eb06f43f | 271 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
0b24becc | 272 | spin_unlock_irqrestore(&report_lock, flags); |
fc5aeeaf | 273 | kasan_enable_current(); |
0b24becc AR |
274 | } |
275 | ||
276 | void kasan_report(unsigned long addr, size_t size, | |
277 | bool is_write, unsigned long ip) | |
278 | { | |
279 | struct kasan_access_info info; | |
280 | ||
0ba8663c | 281 | if (likely(!kasan_report_enabled())) |
0b24becc AR |
282 | return; |
283 | ||
284 | info.access_addr = (void *)addr; | |
285 | info.access_size = size; | |
286 | info.is_write = is_write; | |
287 | info.ip = ip; | |
e9121076 | 288 | |
0b24becc AR |
289 | kasan_report_error(&info); |
290 | } | |
291 | ||
292 | ||
293 | #define DEFINE_ASAN_REPORT_LOAD(size) \ | |
294 | void __asan_report_load##size##_noabort(unsigned long addr) \ | |
295 | { \ | |
296 | kasan_report(addr, size, false, _RET_IP_); \ | |
297 | } \ | |
298 | EXPORT_SYMBOL(__asan_report_load##size##_noabort) | |
299 | ||
300 | #define DEFINE_ASAN_REPORT_STORE(size) \ | |
301 | void __asan_report_store##size##_noabort(unsigned long addr) \ | |
302 | { \ | |
303 | kasan_report(addr, size, true, _RET_IP_); \ | |
304 | } \ | |
305 | EXPORT_SYMBOL(__asan_report_store##size##_noabort) | |
306 | ||
307 | DEFINE_ASAN_REPORT_LOAD(1); | |
308 | DEFINE_ASAN_REPORT_LOAD(2); | |
309 | DEFINE_ASAN_REPORT_LOAD(4); | |
310 | DEFINE_ASAN_REPORT_LOAD(8); | |
311 | DEFINE_ASAN_REPORT_LOAD(16); | |
312 | DEFINE_ASAN_REPORT_STORE(1); | |
313 | DEFINE_ASAN_REPORT_STORE(2); | |
314 | DEFINE_ASAN_REPORT_STORE(4); | |
315 | DEFINE_ASAN_REPORT_STORE(8); | |
316 | DEFINE_ASAN_REPORT_STORE(16); | |
317 | ||
318 | void __asan_report_load_n_noabort(unsigned long addr, size_t size) | |
319 | { | |
320 | kasan_report(addr, size, false, _RET_IP_); | |
321 | } | |
322 | EXPORT_SYMBOL(__asan_report_load_n_noabort); | |
323 | ||
324 | void __asan_report_store_n_noabort(unsigned long addr, size_t size) | |
325 | { | |
326 | kasan_report(addr, size, true, _RET_IP_); | |
327 | } | |
328 | EXPORT_SYMBOL(__asan_report_store_n_noabort); |