Merge tag 'devicetree-fixes-for-4.4' of git://git.kernel.org/pub/scm/linux/kernel...
[firefly-linux-kernel-4.4.55.git] / mm / kasan / report.c
1 /*
2  * This file contains error reporting code.
3  *
4  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
5  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
6  *
7  * Some code borrowed from https://github.com/xairy/kasan-prototype 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 #include <linux/module.h>
26
27 #include <asm/sections.h>
28
29 #include "kasan.h"
30 #include "../slab.h"
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 {
52         const char *bug_type = "unknown-crash";
53         u8 *shadow_addr;
54
55         info->first_bad_addr = find_first_bad_addr(info->access_addr,
56                                                 info->access_size);
57
58         shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
59
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) {
68         case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
69                 /*
70                  * In theory it's still possible to see these shadow values
71                  * due to a data race in the kernel code.
72                  */
73                 bug_type = "out-of-bounds";
74                 break;
75         case KASAN_PAGE_REDZONE:
76         case KASAN_KMALLOC_REDZONE:
77                 bug_type = "slab-out-of-bounds";
78                 break;
79         case KASAN_GLOBAL_REDZONE:
80                 bug_type = "global-out-of-bounds";
81                 break;
82         case KASAN_STACK_LEFT:
83         case KASAN_STACK_MID:
84         case KASAN_STACK_RIGHT:
85         case KASAN_STACK_PARTIAL:
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";
91                 break;
92         }
93
94         pr_err("BUG: KASAN: %s in %pS at addr %p\n",
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
102 static inline bool kernel_or_module_addr(const void *addr)
103 {
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;
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
118 static void print_address_description(struct kasan_access_info *info)
119 {
120         const void *addr = info->access_addr;
121
122         if ((addr >= (void *)PAGE_OFFSET) &&
123                 (addr < high_memory)) {
124                 struct page *page = virt_to_head_page(addr);
125
126                 if (PageSlab(page)) {
127                         void *object;
128                         struct kmem_cache *cache = page->slab_cache;
129                         void *last_object;
130
131                         object = virt_to_obj(cache, page_address(page), addr);
132                         last_object = page_address(page) +
133                                 page->objects * cache->size;
134
135                         if (unlikely(object > last_object))
136                                 object = last_object; /* we hit into padding */
137
138                         object_err(cache, page, object,
139                                 "kasan: bad access detected");
140                         return;
141                 }
142                 dump_page(page, "kasan: bad access detected");
143         }
144
145         if (kernel_or_module_addr(addr)) {
146                 if (!init_task_stack_addr(addr))
147                         pr_err("Address belongs to variable %pS\n", addr);
148         }
149
150         dump_stack();
151 }
152
153 static bool row_is_guilty(const void *row, const void *guilty)
154 {
155         return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
156 }
157
158 static int shadow_pointer_offset(const void *row, const void *shadow)
159 {
160         /* The length of ">ff00ff00ff00ff00: " is
161          *    3 + (BITS_PER_LONG/8)*2 chars.
162          */
163         return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
164                 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
165 }
166
167 static void print_shadow_for_address(const void *addr)
168 {
169         int i;
170         const void *shadow = kasan_mem_to_shadow(addr);
171         const void *shadow_row;
172
173         shadow_row = (void *)round_down((unsigned long)shadow,
174                                         SHADOW_BYTES_PER_ROW)
175                 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
176
177         pr_err("Memory state around the buggy address:\n");
178
179         for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
180                 const void *kaddr = kasan_shadow_to_mem(shadow_row);
181                 char buffer[4 + (BITS_PER_LONG/8)*2];
182                 char shadow_buf[SHADOW_BYTES_PER_ROW];
183
184                 snprintf(buffer, sizeof(buffer),
185                         (i == 0) ? ">%p: " : " %p: ", kaddr);
186                 /*
187                  * We should not pass a shadow pointer to generic
188                  * function, because generic functions may try to
189                  * access kasan mapping for the passed address.
190                  */
191                 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
192                 print_hex_dump(KERN_ERR, buffer,
193                         DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
194                         shadow_buf, SHADOW_BYTES_PER_ROW, 0);
195
196                 if (row_is_guilty(shadow_row, shadow))
197                         pr_err("%*c\n",
198                                 shadow_pointer_offset(shadow_row, shadow),
199                                 '^');
200
201                 shadow_row += SHADOW_BYTES_PER_ROW;
202         }
203 }
204
205 static DEFINE_SPINLOCK(report_lock);
206
207 static void kasan_report_error(struct kasan_access_info *info)
208 {
209         unsigned long flags;
210         const char *bug_type;
211
212         /*
213          * Make sure we don't end up in loop.
214          */
215         kasan_disable_current();
216         spin_lock_irqsave(&report_lock, flags);
217         pr_err("================================="
218                 "=================================\n");
219         if (info->access_addr <
220                         kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
221                 if ((unsigned long)info->access_addr < PAGE_SIZE)
222                         bug_type = "null-ptr-deref";
223                 else if ((unsigned long)info->access_addr < TASK_SIZE)
224                         bug_type = "user-memory-access";
225                 else
226                         bug_type = "wild-memory-access";
227                 pr_err("BUG: KASAN: %s on address %p\n",
228                         bug_type, info->access_addr);
229                 pr_err("%s of size %zu by task %s/%d\n",
230                         info->is_write ? "Write" : "Read",
231                         info->access_size, current->comm,
232                         task_pid_nr(current));
233                 dump_stack();
234         } else {
235                 print_error_description(info);
236                 print_address_description(info);
237                 print_shadow_for_address(info->first_bad_addr);
238         }
239         pr_err("================================="
240                 "=================================\n");
241         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
242         spin_unlock_irqrestore(&report_lock, flags);
243         kasan_enable_current();
244 }
245
246 void kasan_report(unsigned long addr, size_t size,
247                 bool is_write, unsigned long ip)
248 {
249         struct kasan_access_info info;
250
251         if (likely(!kasan_report_enabled()))
252                 return;
253
254         info.access_addr = (void *)addr;
255         info.access_size = size;
256         info.is_write = is_write;
257         info.ip = ip;
258
259         kasan_report_error(&info);
260 }
261
262
263 #define DEFINE_ASAN_REPORT_LOAD(size)                     \
264 void __asan_report_load##size##_noabort(unsigned long addr) \
265 {                                                         \
266         kasan_report(addr, size, false, _RET_IP_);        \
267 }                                                         \
268 EXPORT_SYMBOL(__asan_report_load##size##_noabort)
269
270 #define DEFINE_ASAN_REPORT_STORE(size)                     \
271 void __asan_report_store##size##_noabort(unsigned long addr) \
272 {                                                          \
273         kasan_report(addr, size, true, _RET_IP_);          \
274 }                                                          \
275 EXPORT_SYMBOL(__asan_report_store##size##_noabort)
276
277 DEFINE_ASAN_REPORT_LOAD(1);
278 DEFINE_ASAN_REPORT_LOAD(2);
279 DEFINE_ASAN_REPORT_LOAD(4);
280 DEFINE_ASAN_REPORT_LOAD(8);
281 DEFINE_ASAN_REPORT_LOAD(16);
282 DEFINE_ASAN_REPORT_STORE(1);
283 DEFINE_ASAN_REPORT_STORE(2);
284 DEFINE_ASAN_REPORT_STORE(4);
285 DEFINE_ASAN_REPORT_STORE(8);
286 DEFINE_ASAN_REPORT_STORE(16);
287
288 void __asan_report_load_n_noabort(unsigned long addr, size_t size)
289 {
290         kasan_report(addr, size, false, _RET_IP_);
291 }
292 EXPORT_SYMBOL(__asan_report_load_n_noabort);
293
294 void __asan_report_store_n_noabort(unsigned long addr, size_t size)
295 {
296         kasan_report(addr, size, true, _RET_IP_);
297 }
298 EXPORT_SYMBOL(__asan_report_store_n_noabort);