mm, kasan: SLAB support
[deliverable/linux.git] / mm / kasan / report.c
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1/*
2 * This file contains error reporting code.
3 *
4 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
2baf9e89 5 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
0b24becc 6 *
5d0926ef 7 * Some code borrowed from https://github.com/xairy/kasan-prototype by
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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>
527f215b 25#include <linux/module.h>
0b24becc 26
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27#include <asm/sections.h>
28
0b24becc 29#include "kasan.h"
0316bec2 30#include "../slab.h"
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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
38static 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
50static void print_error_description(struct kasan_access_info *info)
51{
0952d87f 52 const char *bug_type = "unknown-crash";
cdf6a273 53 u8 *shadow_addr;
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54
55 info->first_bad_addr = find_first_bad_addr(info->access_addr,
56 info->access_size);
57
cdf6a273 58 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
0b24becc 59
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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) {
0952d87f 68 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
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69 /*
70 * In theory it's still possible to see these shadow values
71 * due to a data race in the kernel code.
72 */
0952d87f 73 bug_type = "out-of-bounds";
b8c73fc2 74 break;
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75 case KASAN_PAGE_REDZONE:
76 case KASAN_KMALLOC_REDZONE:
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77 bug_type = "slab-out-of-bounds";
78 break;
bebf56a1 79 case KASAN_GLOBAL_REDZONE:
0952d87f 80 bug_type = "global-out-of-bounds";
0b24becc 81 break;
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82 case KASAN_STACK_LEFT:
83 case KASAN_STACK_MID:
84 case KASAN_STACK_RIGHT:
85 case KASAN_STACK_PARTIAL:
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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";
c420f167 91 break;
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92 }
93
25add7ec 94 pr_err("BUG: KASAN: %s in %pS at addr %p\n",
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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
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102static inline bool kernel_or_module_addr(const void *addr)
103{
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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;
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109}
110
111static 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
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118#ifdef CONFIG_SLAB
119static void print_track(struct kasan_track *track)
120{
121 pr_err("PID = %u, CPU = %u, timestamp = %lu\n", track->pid,
122 track->cpu, (unsigned long)track->when);
123}
124
125static void object_err(struct kmem_cache *cache, struct page *page,
126 void *object, char *unused_reason)
127{
128 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
129 struct kasan_free_meta *free_info;
130
131 dump_stack();
132 pr_err("Object at %p, in cache %s\n", object, cache->name);
133 if (!(cache->flags & SLAB_KASAN))
134 return;
135 switch (alloc_info->state) {
136 case KASAN_STATE_INIT:
137 pr_err("Object not allocated yet\n");
138 break;
139 case KASAN_STATE_ALLOC:
140 pr_err("Object allocated with size %u bytes.\n",
141 alloc_info->alloc_size);
142 pr_err("Allocation:\n");
143 print_track(&alloc_info->track);
144 break;
145 case KASAN_STATE_FREE:
146 pr_err("Object freed, allocated with size %u bytes\n",
147 alloc_info->alloc_size);
148 free_info = get_free_info(cache, object);
149 pr_err("Allocation:\n");
150 print_track(&alloc_info->track);
151 pr_err("Deallocation:\n");
152 print_track(&free_info->track);
153 break;
154 }
155}
156#endif
157
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158static void print_address_description(struct kasan_access_info *info)
159{
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160 const void *addr = info->access_addr;
161
162 if ((addr >= (void *)PAGE_OFFSET) &&
163 (addr < high_memory)) {
164 struct page *page = virt_to_head_page(addr);
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165
166 if (PageSlab(page)) {
167 void *object;
168 struct kmem_cache *cache = page->slab_cache;
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169 object = nearest_obj(cache, page,
170 (void *)info->access_addr);
0316bec2 171 object_err(cache, page, object,
7ed2f9e6 172 "kasan: bad access detected");
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173 return;
174 }
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175 dump_page(page, "kasan: bad access detected");
176 }
177
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178 if (kernel_or_module_addr(addr)) {
179 if (!init_task_stack_addr(addr))
180 pr_err("Address belongs to variable %pS\n", addr);
181 }
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182 dump_stack();
183}
184
185static bool row_is_guilty(const void *row, const void *guilty)
186{
187 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
188}
189
190static int shadow_pointer_offset(const void *row, const void *shadow)
191{
192 /* The length of ">ff00ff00ff00ff00: " is
193 * 3 + (BITS_PER_LONG/8)*2 chars.
194 */
195 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
196 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
197}
198
199static void print_shadow_for_address(const void *addr)
200{
201 int i;
202 const void *shadow = kasan_mem_to_shadow(addr);
203 const void *shadow_row;
204
205 shadow_row = (void *)round_down((unsigned long)shadow,
206 SHADOW_BYTES_PER_ROW)
207 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
208
209 pr_err("Memory state around the buggy address:\n");
210
211 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
212 const void *kaddr = kasan_shadow_to_mem(shadow_row);
213 char buffer[4 + (BITS_PER_LONG/8)*2];
f2377d4e 214 char shadow_buf[SHADOW_BYTES_PER_ROW];
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215
216 snprintf(buffer, sizeof(buffer),
217 (i == 0) ? ">%p: " : " %p: ", kaddr);
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218 /*
219 * We should not pass a shadow pointer to generic
220 * function, because generic functions may try to
221 * access kasan mapping for the passed address.
222 */
f2377d4e 223 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
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224 print_hex_dump(KERN_ERR, buffer,
225 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
f2377d4e 226 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
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227
228 if (row_is_guilty(shadow_row, shadow))
229 pr_err("%*c\n",
230 shadow_pointer_offset(shadow_row, shadow),
231 '^');
232
233 shadow_row += SHADOW_BYTES_PER_ROW;
234 }
235}
236
237static DEFINE_SPINLOCK(report_lock);
238
e9121076 239static void kasan_report_error(struct kasan_access_info *info)
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240{
241 unsigned long flags;
e9121076 242 const char *bug_type;
0b24becc 243
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244 /*
245 * Make sure we don't end up in loop.
246 */
247 kasan_disable_current();
0b24becc 248 spin_lock_irqsave(&report_lock, flags);
756a025f 249 pr_err("==================================================================\n");
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250 if (info->access_addr <
251 kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
252 if ((unsigned long)info->access_addr < PAGE_SIZE)
253 bug_type = "null-ptr-deref";
254 else if ((unsigned long)info->access_addr < TASK_SIZE)
255 bug_type = "user-memory-access";
256 else
257 bug_type = "wild-memory-access";
25add7ec 258 pr_err("BUG: KASAN: %s on address %p\n",
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259 bug_type, info->access_addr);
260 pr_err("%s of size %zu by task %s/%d\n",
261 info->is_write ? "Write" : "Read",
262 info->access_size, current->comm,
263 task_pid_nr(current));
264 dump_stack();
265 } else {
266 print_error_description(info);
267 print_address_description(info);
268 print_shadow_for_address(info->first_bad_addr);
269 }
756a025f 270 pr_err("==================================================================\n");
eb06f43f 271 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
0b24becc 272 spin_unlock_irqrestore(&report_lock, flags);
fc5aeeaf 273 kasan_enable_current();
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274}
275
276void kasan_report(unsigned long addr, size_t size,
277 bool is_write, unsigned long ip)
278{
279 struct kasan_access_info info;
280
0ba8663c 281 if (likely(!kasan_report_enabled()))
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282 return;
283
284 info.access_addr = (void *)addr;
285 info.access_size = size;
286 info.is_write = is_write;
287 info.ip = ip;
e9121076 288
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289 kasan_report_error(&info);
290}
291
292
293#define DEFINE_ASAN_REPORT_LOAD(size) \
294void __asan_report_load##size##_noabort(unsigned long addr) \
295{ \
296 kasan_report(addr, size, false, _RET_IP_); \
297} \
298EXPORT_SYMBOL(__asan_report_load##size##_noabort)
299
300#define DEFINE_ASAN_REPORT_STORE(size) \
301void __asan_report_store##size##_noabort(unsigned long addr) \
302{ \
303 kasan_report(addr, size, true, _RET_IP_); \
304} \
305EXPORT_SYMBOL(__asan_report_store##size##_noabort)
306
307DEFINE_ASAN_REPORT_LOAD(1);
308DEFINE_ASAN_REPORT_LOAD(2);
309DEFINE_ASAN_REPORT_LOAD(4);
310DEFINE_ASAN_REPORT_LOAD(8);
311DEFINE_ASAN_REPORT_LOAD(16);
312DEFINE_ASAN_REPORT_STORE(1);
313DEFINE_ASAN_REPORT_STORE(2);
314DEFINE_ASAN_REPORT_STORE(4);
315DEFINE_ASAN_REPORT_STORE(8);
316DEFINE_ASAN_REPORT_STORE(16);
317
318void __asan_report_load_n_noabort(unsigned long addr, size_t size)
319{
320 kasan_report(addr, size, false, _RET_IP_);
321}
322EXPORT_SYMBOL(__asan_report_load_n_noabort);
323
324void __asan_report_store_n_noabort(unsigned long addr, size_t size)
325{
326 kasan_report(addr, size, true, _RET_IP_);
327}
328EXPORT_SYMBOL(__asan_report_store_n_noabort);
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