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