1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * This file contains generic KASAN specific error reporting code.
4 *
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 *
8 * Some code borrowed from https://github.com/xairy/kasan-prototype by
9 * Andrey Konovalov <andreyknvl@gmail.com>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 *
15 */
16
17 #include <linux/bitops.h>
18 #include <linux/ftrace.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/mm.h>
22 #include <linux/printk.h>
23 #include <linux/sched.h>
24 #include <linux/slab.h>
25 #include <linux/stackdepot.h>
26 #include <linux/stacktrace.h>
27 #include <linux/string.h>
28 #include <linux/types.h>
29 #include <linux/kasan.h>
30 #include <linux/module.h>
31
32 #include <asm/sections.h>
33
34 #include "kasan.h"
35 #include "../slab.h"
36
find_first_bad_addr(void * addr,size_t size)37 void *find_first_bad_addr(void *addr, size_t size)
38 {
39 void *p = addr;
40
41 while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
42 p += KASAN_SHADOW_SCALE_SIZE;
43 return p;
44 }
45
get_shadow_bug_type(struct kasan_access_info * info)46 static const char *get_shadow_bug_type(struct kasan_access_info *info)
47 {
48 const char *bug_type = "unknown-crash";
49 u8 *shadow_addr;
50
51 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
52
53 /*
54 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
55 * at the next shadow byte to determine the type of the bad access.
56 */
57 if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
58 shadow_addr++;
59
60 switch (*shadow_addr) {
61 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
62 /*
63 * In theory it's still possible to see these shadow values
64 * due to a data race in the kernel code.
65 */
66 bug_type = "out-of-bounds";
67 break;
68 case KASAN_PAGE_REDZONE:
69 case KASAN_KMALLOC_REDZONE:
70 bug_type = "slab-out-of-bounds";
71 break;
72 case KASAN_GLOBAL_REDZONE:
73 bug_type = "global-out-of-bounds";
74 break;
75 case KASAN_STACK_LEFT:
76 case KASAN_STACK_MID:
77 case KASAN_STACK_RIGHT:
78 case KASAN_STACK_PARTIAL:
79 bug_type = "stack-out-of-bounds";
80 break;
81 case KASAN_FREE_PAGE:
82 case KASAN_KMALLOC_FREE:
83 case KASAN_KMALLOC_FREETRACK:
84 bug_type = "use-after-free";
85 break;
86 case KASAN_ALLOCA_LEFT:
87 case KASAN_ALLOCA_RIGHT:
88 bug_type = "alloca-out-of-bounds";
89 break;
90 case KASAN_VMALLOC_INVALID:
91 bug_type = "vmalloc-out-of-bounds";
92 break;
93 }
94
95 return bug_type;
96 }
97
get_wild_bug_type(struct kasan_access_info * info)98 static const char *get_wild_bug_type(struct kasan_access_info *info)
99 {
100 const char *bug_type = "unknown-crash";
101
102 if ((unsigned long)info->access_addr < PAGE_SIZE)
103 bug_type = "null-ptr-deref";
104 else if ((unsigned long)info->access_addr < TASK_SIZE)
105 bug_type = "user-memory-access";
106 else
107 bug_type = "wild-memory-access";
108
109 return bug_type;
110 }
111
get_bug_type(struct kasan_access_info * info)112 const char *get_bug_type(struct kasan_access_info *info)
113 {
114 /*
115 * If access_size is a negative number, then it has reason to be
116 * defined as out-of-bounds bug type.
117 *
118 * Casting negative numbers to size_t would indeed turn up as
119 * a large size_t and its value will be larger than ULONG_MAX/2,
120 * so that this can qualify as out-of-bounds.
121 */
122 if (info->access_addr + info->access_size < info->access_addr)
123 return "out-of-bounds";
124
125 if (addr_has_shadow(info->access_addr))
126 return get_shadow_bug_type(info);
127 return get_wild_bug_type(info);
128 }
129
130 #define DEFINE_ASAN_REPORT_LOAD(size) \
131 void __asan_report_load##size##_noabort(unsigned long addr) \
132 { \
133 kasan_report(addr, size, false, _RET_IP_); \
134 } \
135 EXPORT_SYMBOL(__asan_report_load##size##_noabort)
136
137 #define DEFINE_ASAN_REPORT_STORE(size) \
138 void __asan_report_store##size##_noabort(unsigned long addr) \
139 { \
140 kasan_report(addr, size, true, _RET_IP_); \
141 } \
142 EXPORT_SYMBOL(__asan_report_store##size##_noabort)
143
144 DEFINE_ASAN_REPORT_LOAD(1);
145 DEFINE_ASAN_REPORT_LOAD(2);
146 DEFINE_ASAN_REPORT_LOAD(4);
147 DEFINE_ASAN_REPORT_LOAD(8);
148 DEFINE_ASAN_REPORT_LOAD(16);
149 DEFINE_ASAN_REPORT_STORE(1);
150 DEFINE_ASAN_REPORT_STORE(2);
151 DEFINE_ASAN_REPORT_STORE(4);
152 DEFINE_ASAN_REPORT_STORE(8);
153 DEFINE_ASAN_REPORT_STORE(16);
154
__asan_report_load_n_noabort(unsigned long addr,size_t size)155 void __asan_report_load_n_noabort(unsigned long addr, size_t size)
156 {
157 kasan_report(addr, size, false, _RET_IP_);
158 }
159 EXPORT_SYMBOL(__asan_report_load_n_noabort);
160
__asan_report_store_n_noabort(unsigned long addr,size_t size)161 void __asan_report_store_n_noabort(unsigned long addr, size_t size)
162 {
163 kasan_report(addr, size, true, _RET_IP_);
164 }
165 EXPORT_SYMBOL(__asan_report_store_n_noabort);
166