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0b24becc AR |
1 | /* |
2 | * This file contains error reporting code. | |
3 | * | |
4 | * Copyright (c) 2014 Samsung Electronics Co., Ltd. | |
5 | * Author: Andrey Ryabinin <a.ryabinin@samsung.com> | |
6 | * | |
7 | * Some of code borrowed from https://github.com/xairy/linux by | |
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> | |
25 | ||
bebf56a1 AR |
26 | #include <asm/sections.h> |
27 | ||
0b24becc | 28 | #include "kasan.h" |
0316bec2 | 29 | #include "../slab.h" |
0b24becc AR |
30 | |
31 | /* Shadow layout customization. */ | |
32 | #define SHADOW_BYTES_PER_BLOCK 1 | |
33 | #define SHADOW_BLOCKS_PER_ROW 16 | |
34 | #define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK) | |
35 | #define SHADOW_ROWS_AROUND_ADDR 2 | |
36 | ||
37 | static const void *find_first_bad_addr(const void *addr, size_t size) | |
38 | { | |
39 | u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr); | |
40 | const void *first_bad_addr = addr; | |
41 | ||
42 | while (!shadow_val && first_bad_addr < addr + size) { | |
43 | first_bad_addr += KASAN_SHADOW_SCALE_SIZE; | |
44 | shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr); | |
45 | } | |
46 | return first_bad_addr; | |
47 | } | |
48 | ||
49 | static void print_error_description(struct kasan_access_info *info) | |
50 | { | |
51 | const char *bug_type = "unknown crash"; | |
52 | u8 shadow_val; | |
53 | ||
54 | info->first_bad_addr = find_first_bad_addr(info->access_addr, | |
55 | info->access_size); | |
56 | ||
57 | shadow_val = *(u8 *)kasan_mem_to_shadow(info->first_bad_addr); | |
58 | ||
59 | switch (shadow_val) { | |
b8c73fc2 | 60 | case KASAN_FREE_PAGE: |
0316bec2 | 61 | case KASAN_KMALLOC_FREE: |
b8c73fc2 AR |
62 | bug_type = "use after free"; |
63 | break; | |
0316bec2 AR |
64 | case KASAN_PAGE_REDZONE: |
65 | case KASAN_KMALLOC_REDZONE: | |
bebf56a1 | 66 | case KASAN_GLOBAL_REDZONE: |
0b24becc AR |
67 | case 0 ... KASAN_SHADOW_SCALE_SIZE - 1: |
68 | bug_type = "out of bounds access"; | |
69 | break; | |
c420f167 AR |
70 | case KASAN_STACK_LEFT: |
71 | case KASAN_STACK_MID: | |
72 | case KASAN_STACK_RIGHT: | |
73 | case KASAN_STACK_PARTIAL: | |
74 | bug_type = "out of bounds on stack"; | |
75 | break; | |
0b24becc AR |
76 | } |
77 | ||
78 | pr_err("BUG: KASan: %s in %pS at addr %p\n", | |
79 | bug_type, (void *)info->ip, | |
80 | info->access_addr); | |
81 | pr_err("%s of size %zu by task %s/%d\n", | |
82 | info->is_write ? "Write" : "Read", | |
83 | info->access_size, current->comm, task_pid_nr(current)); | |
84 | } | |
85 | ||
bebf56a1 AR |
86 | static inline bool kernel_or_module_addr(const void *addr) |
87 | { | |
88 | return (addr >= (void *)_stext && addr < (void *)_end) | |
89 | || (addr >= (void *)MODULES_VADDR | |
90 | && addr < (void *)MODULES_END); | |
91 | } | |
92 | ||
93 | static inline bool init_task_stack_addr(const void *addr) | |
94 | { | |
95 | return addr >= (void *)&init_thread_union.stack && | |
96 | (addr <= (void *)&init_thread_union.stack + | |
97 | sizeof(init_thread_union.stack)); | |
98 | } | |
99 | ||
0b24becc AR |
100 | static void print_address_description(struct kasan_access_info *info) |
101 | { | |
b8c73fc2 AR |
102 | const void *addr = info->access_addr; |
103 | ||
104 | if ((addr >= (void *)PAGE_OFFSET) && | |
105 | (addr < high_memory)) { | |
106 | struct page *page = virt_to_head_page(addr); | |
0316bec2 AR |
107 | |
108 | if (PageSlab(page)) { | |
109 | void *object; | |
110 | struct kmem_cache *cache = page->slab_cache; | |
111 | void *last_object; | |
112 | ||
113 | object = virt_to_obj(cache, page_address(page), addr); | |
114 | last_object = page_address(page) + | |
115 | page->objects * cache->size; | |
116 | ||
117 | if (unlikely(object > last_object)) | |
118 | object = last_object; /* we hit into padding */ | |
119 | ||
120 | object_err(cache, page, object, | |
121 | "kasan: bad access detected"); | |
122 | return; | |
123 | } | |
b8c73fc2 AR |
124 | dump_page(page, "kasan: bad access detected"); |
125 | } | |
126 | ||
bebf56a1 AR |
127 | if (kernel_or_module_addr(addr)) { |
128 | if (!init_task_stack_addr(addr)) | |
129 | pr_err("Address belongs to variable %pS\n", addr); | |
130 | } | |
131 | ||
0b24becc AR |
132 | dump_stack(); |
133 | } | |
134 | ||
135 | static bool row_is_guilty(const void *row, const void *guilty) | |
136 | { | |
137 | return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); | |
138 | } | |
139 | ||
140 | static int shadow_pointer_offset(const void *row, const void *shadow) | |
141 | { | |
142 | /* The length of ">ff00ff00ff00ff00: " is | |
143 | * 3 + (BITS_PER_LONG/8)*2 chars. | |
144 | */ | |
145 | return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + | |
146 | (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; | |
147 | } | |
148 | ||
149 | static void print_shadow_for_address(const void *addr) | |
150 | { | |
151 | int i; | |
152 | const void *shadow = kasan_mem_to_shadow(addr); | |
153 | const void *shadow_row; | |
154 | ||
155 | shadow_row = (void *)round_down((unsigned long)shadow, | |
156 | SHADOW_BYTES_PER_ROW) | |
157 | - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; | |
158 | ||
159 | pr_err("Memory state around the buggy address:\n"); | |
160 | ||
161 | for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) { | |
162 | const void *kaddr = kasan_shadow_to_mem(shadow_row); | |
163 | char buffer[4 + (BITS_PER_LONG/8)*2]; | |
164 | ||
165 | snprintf(buffer, sizeof(buffer), | |
166 | (i == 0) ? ">%p: " : " %p: ", kaddr); | |
167 | ||
168 | kasan_disable_current(); | |
169 | print_hex_dump(KERN_ERR, buffer, | |
170 | DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, | |
171 | shadow_row, SHADOW_BYTES_PER_ROW, 0); | |
172 | kasan_enable_current(); | |
173 | ||
174 | if (row_is_guilty(shadow_row, shadow)) | |
175 | pr_err("%*c\n", | |
176 | shadow_pointer_offset(shadow_row, shadow), | |
177 | '^'); | |
178 | ||
179 | shadow_row += SHADOW_BYTES_PER_ROW; | |
180 | } | |
181 | } | |
182 | ||
183 | static DEFINE_SPINLOCK(report_lock); | |
184 | ||
185 | void kasan_report_error(struct kasan_access_info *info) | |
186 | { | |
187 | unsigned long flags; | |
188 | ||
189 | spin_lock_irqsave(&report_lock, flags); | |
190 | pr_err("=================================" | |
191 | "=================================\n"); | |
192 | print_error_description(info); | |
193 | print_address_description(info); | |
194 | print_shadow_for_address(info->first_bad_addr); | |
195 | pr_err("=================================" | |
196 | "=================================\n"); | |
197 | spin_unlock_irqrestore(&report_lock, flags); | |
198 | } | |
199 | ||
200 | void kasan_report_user_access(struct kasan_access_info *info) | |
201 | { | |
202 | unsigned long flags; | |
203 | ||
204 | spin_lock_irqsave(&report_lock, flags); | |
205 | pr_err("=================================" | |
206 | "=================================\n"); | |
207 | pr_err("BUG: KASan: user-memory-access on address %p\n", | |
208 | info->access_addr); | |
209 | pr_err("%s of size %zu by task %s/%d\n", | |
210 | info->is_write ? "Write" : "Read", | |
211 | info->access_size, current->comm, task_pid_nr(current)); | |
212 | dump_stack(); | |
213 | pr_err("=================================" | |
214 | "=================================\n"); | |
215 | spin_unlock_irqrestore(&report_lock, flags); | |
216 | } | |
217 | ||
218 | void kasan_report(unsigned long addr, size_t size, | |
219 | bool is_write, unsigned long ip) | |
220 | { | |
221 | struct kasan_access_info info; | |
222 | ||
223 | if (likely(!kasan_enabled())) | |
224 | return; | |
225 | ||
226 | info.access_addr = (void *)addr; | |
227 | info.access_size = size; | |
228 | info.is_write = is_write; | |
229 | info.ip = ip; | |
230 | kasan_report_error(&info); | |
231 | } | |
232 | ||
233 | ||
234 | #define DEFINE_ASAN_REPORT_LOAD(size) \ | |
235 | void __asan_report_load##size##_noabort(unsigned long addr) \ | |
236 | { \ | |
237 | kasan_report(addr, size, false, _RET_IP_); \ | |
238 | } \ | |
239 | EXPORT_SYMBOL(__asan_report_load##size##_noabort) | |
240 | ||
241 | #define DEFINE_ASAN_REPORT_STORE(size) \ | |
242 | void __asan_report_store##size##_noabort(unsigned long addr) \ | |
243 | { \ | |
244 | kasan_report(addr, size, true, _RET_IP_); \ | |
245 | } \ | |
246 | EXPORT_SYMBOL(__asan_report_store##size##_noabort) | |
247 | ||
248 | DEFINE_ASAN_REPORT_LOAD(1); | |
249 | DEFINE_ASAN_REPORT_LOAD(2); | |
250 | DEFINE_ASAN_REPORT_LOAD(4); | |
251 | DEFINE_ASAN_REPORT_LOAD(8); | |
252 | DEFINE_ASAN_REPORT_LOAD(16); | |
253 | DEFINE_ASAN_REPORT_STORE(1); | |
254 | DEFINE_ASAN_REPORT_STORE(2); | |
255 | DEFINE_ASAN_REPORT_STORE(4); | |
256 | DEFINE_ASAN_REPORT_STORE(8); | |
257 | DEFINE_ASAN_REPORT_STORE(16); | |
258 | ||
259 | void __asan_report_load_n_noabort(unsigned long addr, size_t size) | |
260 | { | |
261 | kasan_report(addr, size, false, _RET_IP_); | |
262 | } | |
263 | EXPORT_SYMBOL(__asan_report_load_n_noabort); | |
264 | ||
265 | void __asan_report_store_n_noabort(unsigned long addr, size_t size) | |
266 | { | |
267 | kasan_report(addr, size, true, _RET_IP_); | |
268 | } | |
269 | EXPORT_SYMBOL(__asan_report_store_n_noabort); |