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