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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 <andreyknvl@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/bitops.h>
17#include <linux/ftrace.h>
18#include <linux/init.h>
19#include <linux/kernel.h>
20#include <linux/mm.h>
21#include <linux/printk.h>
22#include <linux/sched.h>
23#include <linux/slab.h>
24#include <linux/stackdepot.h>
25#include <linux/stacktrace.h>
26#include <linux/string.h>
27#include <linux/types.h>
28#include <linux/kasan.h>
29#include <linux/module.h>
30
31#include <asm/sections.h>
32
33#include "kasan.h"
34#include "../slab.h"
35
36/* Shadow layout customization. */
37#define SHADOW_BYTES_PER_BLOCK 1
38#define SHADOW_BLOCKS_PER_ROW 16
39#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
40#define SHADOW_ROWS_AROUND_ADDR 2
41
42static const void *find_first_bad_addr(const void *addr, size_t size)
43{
44 u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
45 const void *first_bad_addr = addr;
46
47 while (!shadow_val && first_bad_addr < addr + size) {
48 first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
49 shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
50 }
51 return first_bad_addr;
52}
53
54static bool addr_has_shadow(struct kasan_access_info *info)
55{
56 return (info->access_addr >=
57 kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
58}
59
60static const char *get_shadow_bug_type(struct kasan_access_info *info)
61{
62 const char *bug_type = "unknown-crash";
63 u8 *shadow_addr;
64
65 info->first_bad_addr = find_first_bad_addr(info->access_addr,
66 info->access_size);
67
68 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
69
70 /*
71 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
72 * at the next shadow byte to determine the type of the bad access.
73 */
74 if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
75 shadow_addr++;
76
77 switch (*shadow_addr) {
78 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
79 /*
80 * In theory it's still possible to see these shadow values
81 * due to a data race in the kernel code.
82 */
83 bug_type = "out-of-bounds";
84 break;
85 case KASAN_PAGE_REDZONE:
86 case KASAN_KMALLOC_REDZONE:
87 bug_type = "slab-out-of-bounds";
88 break;
89 case KASAN_GLOBAL_REDZONE:
90 bug_type = "global-out-of-bounds";
91 break;
92 case KASAN_STACK_LEFT:
93 case KASAN_STACK_MID:
94 case KASAN_STACK_RIGHT:
95 case KASAN_STACK_PARTIAL:
96 bug_type = "stack-out-of-bounds";
97 break;
98 case KASAN_FREE_PAGE:
99 case KASAN_KMALLOC_FREE:
100 bug_type = "use-after-free";
101 break;
102 case KASAN_USE_AFTER_SCOPE:
103 bug_type = "use-after-scope";
104 break;
105 case KASAN_ALLOCA_LEFT:
106 case KASAN_ALLOCA_RIGHT:
107 bug_type = "alloca-out-of-bounds";
108 break;
109 }
110
111 return bug_type;
112}
113
114static const char *get_wild_bug_type(struct kasan_access_info *info)
115{
116 const char *bug_type = "unknown-crash";
117
118 if ((unsigned long)info->access_addr < PAGE_SIZE)
119 bug_type = "null-ptr-deref";
120 else if ((unsigned long)info->access_addr < TASK_SIZE)
121 bug_type = "user-memory-access";
122 else
123 bug_type = "wild-memory-access";
124
125 return bug_type;
126}
127
128static const char *get_bug_type(struct kasan_access_info *info)
129{
130 if (addr_has_shadow(info))
131 return get_shadow_bug_type(info);
132 return get_wild_bug_type(info);
133}
134
135static void print_error_description(struct kasan_access_info *info)
136{
137 const char *bug_type = get_bug_type(info);
138
139 pr_err("BUG: KASAN: %s in %pS\n",
140 bug_type, (void *)info->ip);
141 pr_err("%s of size %zu at addr %px by task %s/%d\n",
142 info->is_write ? "Write" : "Read", info->access_size,
143 info->access_addr, current->comm, task_pid_nr(current));
144}
145
146static inline bool kernel_or_module_addr(const void *addr)
147{
148 if (addr >= (void *)_stext && addr < (void *)_end)
149 return true;
150 if (is_module_address((unsigned long)addr))
151 return true;
152 return false;
153}
154
155static inline bool init_task_stack_addr(const void *addr)
156{
157 return addr >= (void *)&init_thread_union.stack &&
158 (addr <= (void *)&init_thread_union.stack +
159 sizeof(init_thread_union.stack));
160}
161
162static DEFINE_SPINLOCK(report_lock);
163
164static void kasan_start_report(unsigned long *flags)
165{
166 /*
167 * Make sure we don't end up in loop.
168 */
169 kasan_disable_current();
170 spin_lock_irqsave(&report_lock, *flags);
171 pr_err("==================================================================\n");
172}
173
174static void kasan_end_report(unsigned long *flags)
175{
176 pr_err("==================================================================\n");
177 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
178 spin_unlock_irqrestore(&report_lock, *flags);
179 if (panic_on_warn)
180 panic("panic_on_warn set ...\n");
181 kasan_enable_current();
182}
183
184static void print_track(struct kasan_track *track, const char *prefix)
185{
186 pr_err("%s by task %u:\n", prefix, track->pid);
187 if (track->stack) {
188 struct stack_trace trace;
189
190 depot_fetch_stack(track->stack, &trace);
191 print_stack_trace(&trace, 0);
192 } else {
193 pr_err("(stack is not available)\n");
194 }
195}
196
197static struct page *addr_to_page(const void *addr)
198{
199 if ((addr >= (void *)PAGE_OFFSET) &&
200 (addr < high_memory))
201 return virt_to_head_page(addr);
202 return NULL;
203}
204
205static void describe_object_addr(struct kmem_cache *cache, void *object,
206 const void *addr)
207{
208 unsigned long access_addr = (unsigned long)addr;
209 unsigned long object_addr = (unsigned long)object;
210 const char *rel_type;
211 int rel_bytes;
212
213 pr_err("The buggy address belongs to the object at %px\n"
214 " which belongs to the cache %s of size %d\n",
215 object, cache->name, cache->object_size);
216
217 if (!addr)
218 return;
219
220 if (access_addr < object_addr) {
221 rel_type = "to the left";
222 rel_bytes = object_addr - access_addr;
223 } else if (access_addr >= object_addr + cache->object_size) {
224 rel_type = "to the right";
225 rel_bytes = access_addr - (object_addr + cache->object_size);
226 } else {
227 rel_type = "inside";
228 rel_bytes = access_addr - object_addr;
229 }
230
231 pr_err("The buggy address is located %d bytes %s of\n"
232 " %d-byte region [%px, %px)\n",
233 rel_bytes, rel_type, cache->object_size, (void *)object_addr,
234 (void *)(object_addr + cache->object_size));
235}
236
237static void describe_object(struct kmem_cache *cache, void *object,
238 const void *addr)
239{
240 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
241
242 if (cache->flags & SLAB_KASAN) {
243 print_track(&alloc_info->alloc_track, "Allocated");
244 pr_err("\n");
245 print_track(&alloc_info->free_track, "Freed");
246 pr_err("\n");
247 }
248
249 describe_object_addr(cache, object, addr);
250}
251
252static void print_address_description(void *addr)
253{
254 struct page *page = addr_to_page(addr);
255
256 dump_stack();
257 pr_err("\n");
258
259 if (page && PageSlab(page)) {
260 struct kmem_cache *cache = page->slab_cache;
261 void *object = nearest_obj(cache, page, addr);
262
263 describe_object(cache, object, addr);
264 }
265
266 if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
267 pr_err("The buggy address belongs to the variable:\n");
268 pr_err(" %pS\n", addr);
269 }
270
271 if (page) {
272 pr_err("The buggy address belongs to the page:\n");
273 dump_page(page, "kasan: bad access detected");
274 }
275}
276
277static bool row_is_guilty(const void *row, const void *guilty)
278{
279 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
280}
281
282static int shadow_pointer_offset(const void *row, const void *shadow)
283{
284 /* The length of ">ff00ff00ff00ff00: " is
285 * 3 + (BITS_PER_LONG/8)*2 chars.
286 */
287 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
288 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
289}
290
291static void print_shadow_for_address(const void *addr)
292{
293 int i;
294 const void *shadow = kasan_mem_to_shadow(addr);
295 const void *shadow_row;
296
297 shadow_row = (void *)round_down((unsigned long)shadow,
298 SHADOW_BYTES_PER_ROW)
299 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
300
301 pr_err("Memory state around the buggy address:\n");
302
303 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
304 const void *kaddr = kasan_shadow_to_mem(shadow_row);
305 char buffer[4 + (BITS_PER_LONG/8)*2];
306 char shadow_buf[SHADOW_BYTES_PER_ROW];
307
308 snprintf(buffer, sizeof(buffer),
309 (i == 0) ? ">%px: " : " %px: ", kaddr);
310 /*
311 * We should not pass a shadow pointer to generic
312 * function, because generic functions may try to
313 * access kasan mapping for the passed address.
314 */
315 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
316 print_hex_dump(KERN_ERR, buffer,
317 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
318 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
319
320 if (row_is_guilty(shadow_row, shadow))
321 pr_err("%*c\n",
322 shadow_pointer_offset(shadow_row, shadow),
323 '^');
324
325 shadow_row += SHADOW_BYTES_PER_ROW;
326 }
327}
328
329void kasan_report_invalid_free(void *object, unsigned long ip)
330{
331 unsigned long flags;
332
333 kasan_start_report(&flags);
334 pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
335 pr_err("\n");
336 print_address_description(object);
337 pr_err("\n");
338 print_shadow_for_address(object);
339 kasan_end_report(&flags);
340}
341
342static void kasan_report_error(struct kasan_access_info *info)
343{
344 unsigned long flags;
345
346 kasan_start_report(&flags);
347
348 print_error_description(info);
349 pr_err("\n");
350
351 if (!addr_has_shadow(info)) {
352 dump_stack();
353 } else {
354 print_address_description((void *)info->access_addr);
355 pr_err("\n");
356 print_shadow_for_address(info->first_bad_addr);
357 }
358
359 kasan_end_report(&flags);
360}
361
362static unsigned long kasan_flags;
363
364#define KASAN_BIT_REPORTED 0
365#define KASAN_BIT_MULTI_SHOT 1
366
367bool kasan_save_enable_multi_shot(void)
368{
369 return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
370}
371EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
372
373void kasan_restore_multi_shot(bool enabled)
374{
375 if (!enabled)
376 clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
377}
378EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
379
380static int __init kasan_set_multi_shot(char *str)
381{
382 set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
383 return 1;
384}
385__setup("kasan_multi_shot", kasan_set_multi_shot);
386
387static inline bool kasan_report_enabled(void)
388{
389 if (current->kasan_depth)
390 return false;
391 if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
392 return true;
393 return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
394}
395
396void kasan_report(unsigned long addr, size_t size,
397 bool is_write, unsigned long ip)
398{
399 struct kasan_access_info info;
400
401 if (likely(!kasan_report_enabled()))
402 return;
403
404 disable_trace_on_warning();
405
406 info.access_addr = (void *)addr;
407 info.first_bad_addr = (void *)addr;
408 info.access_size = size;
409 info.is_write = is_write;
410 info.ip = ip;
411
412 kasan_report_error(&info);
413}
414
415
416#define DEFINE_ASAN_REPORT_LOAD(size) \
417void __asan_report_load##size##_noabort(unsigned long addr) \
418{ \
419 kasan_report(addr, size, false, _RET_IP_); \
420} \
421EXPORT_SYMBOL(__asan_report_load##size##_noabort)
422
423#define DEFINE_ASAN_REPORT_STORE(size) \
424void __asan_report_store##size##_noabort(unsigned long addr) \
425{ \
426 kasan_report(addr, size, true, _RET_IP_); \
427} \
428EXPORT_SYMBOL(__asan_report_store##size##_noabort)
429
430DEFINE_ASAN_REPORT_LOAD(1);
431DEFINE_ASAN_REPORT_LOAD(2);
432DEFINE_ASAN_REPORT_LOAD(4);
433DEFINE_ASAN_REPORT_LOAD(8);
434DEFINE_ASAN_REPORT_LOAD(16);
435DEFINE_ASAN_REPORT_STORE(1);
436DEFINE_ASAN_REPORT_STORE(2);
437DEFINE_ASAN_REPORT_STORE(4);
438DEFINE_ASAN_REPORT_STORE(8);
439DEFINE_ASAN_REPORT_STORE(16);
440
441void __asan_report_load_n_noabort(unsigned long addr, size_t size)
442{
443 kasan_report(addr, size, false, _RET_IP_);
444}
445EXPORT_SYMBOL(__asan_report_load_n_noabort);
446
447void __asan_report_store_n_noabort(unsigned long addr, size_t size)
448{
449 kasan_report(addr, size, true, _RET_IP_);
450}
451EXPORT_SYMBOL(__asan_report_store_n_noabort);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This file contains common KASAN 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
12#include <kunit/test.h>
13#include <linux/bitops.h>
14#include <linux/ftrace.h>
15#include <linux/init.h>
16#include <linux/kernel.h>
17#include <linux/lockdep.h>
18#include <linux/mm.h>
19#include <linux/printk.h>
20#include <linux/sched.h>
21#include <linux/slab.h>
22#include <linux/stackdepot.h>
23#include <linux/stacktrace.h>
24#include <linux/string.h>
25#include <linux/types.h>
26#include <linux/kasan.h>
27#include <linux/module.h>
28#include <linux/sched/task_stack.h>
29#include <linux/uaccess.h>
30#include <trace/events/error_report.h>
31
32#include <asm/sections.h>
33
34#include "kasan.h"
35#include "../slab.h"
36
37static unsigned long kasan_flags;
38
39#define KASAN_BIT_REPORTED 0
40#define KASAN_BIT_MULTI_SHOT 1
41
42enum kasan_arg_fault {
43 KASAN_ARG_FAULT_DEFAULT,
44 KASAN_ARG_FAULT_REPORT,
45 KASAN_ARG_FAULT_PANIC,
46};
47
48static enum kasan_arg_fault kasan_arg_fault __ro_after_init = KASAN_ARG_FAULT_DEFAULT;
49
50/* kasan.fault=report/panic */
51static int __init early_kasan_fault(char *arg)
52{
53 if (!arg)
54 return -EINVAL;
55
56 if (!strcmp(arg, "report"))
57 kasan_arg_fault = KASAN_ARG_FAULT_REPORT;
58 else if (!strcmp(arg, "panic"))
59 kasan_arg_fault = KASAN_ARG_FAULT_PANIC;
60 else
61 return -EINVAL;
62
63 return 0;
64}
65early_param("kasan.fault", early_kasan_fault);
66
67static int __init kasan_set_multi_shot(char *str)
68{
69 set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
70 return 1;
71}
72__setup("kasan_multi_shot", kasan_set_multi_shot);
73
74/*
75 * Used to suppress reports within kasan_disable/enable_current() critical
76 * sections, which are used for marking accesses to slab metadata.
77 */
78static bool report_suppressed(void)
79{
80#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
81 if (current->kasan_depth)
82 return true;
83#endif
84 return false;
85}
86
87/*
88 * Used to avoid reporting more than one KASAN bug unless kasan_multi_shot
89 * is enabled. Note that KASAN tests effectively enable kasan_multi_shot
90 * for their duration.
91 */
92static bool report_enabled(void)
93{
94 if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
95 return true;
96 return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
97}
98
99#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST) || IS_ENABLED(CONFIG_KASAN_MODULE_TEST)
100
101bool kasan_save_enable_multi_shot(void)
102{
103 return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
104}
105EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
106
107void kasan_restore_multi_shot(bool enabled)
108{
109 if (!enabled)
110 clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
111}
112EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
113
114#endif
115
116#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
117
118/*
119 * Whether the KASAN KUnit test suite is currently being executed.
120 * Updated in kasan_test.c.
121 */
122static bool kasan_kunit_executing;
123
124void kasan_kunit_test_suite_start(void)
125{
126 WRITE_ONCE(kasan_kunit_executing, true);
127}
128EXPORT_SYMBOL_GPL(kasan_kunit_test_suite_start);
129
130void kasan_kunit_test_suite_end(void)
131{
132 WRITE_ONCE(kasan_kunit_executing, false);
133}
134EXPORT_SYMBOL_GPL(kasan_kunit_test_suite_end);
135
136static bool kasan_kunit_test_suite_executing(void)
137{
138 return READ_ONCE(kasan_kunit_executing);
139}
140
141#else /* CONFIG_KASAN_KUNIT_TEST */
142
143static inline bool kasan_kunit_test_suite_executing(void) { return false; }
144
145#endif /* CONFIG_KASAN_KUNIT_TEST */
146
147#if IS_ENABLED(CONFIG_KUNIT)
148
149static void fail_non_kasan_kunit_test(void)
150{
151 struct kunit *test;
152
153 if (kasan_kunit_test_suite_executing())
154 return;
155
156 test = current->kunit_test;
157 if (test)
158 kunit_set_failure(test);
159}
160
161#else /* CONFIG_KUNIT */
162
163static inline void fail_non_kasan_kunit_test(void) { }
164
165#endif /* CONFIG_KUNIT */
166
167static DEFINE_SPINLOCK(report_lock);
168
169static void start_report(unsigned long *flags, bool sync)
170{
171 fail_non_kasan_kunit_test();
172 /* Respect the /proc/sys/kernel/traceoff_on_warning interface. */
173 disable_trace_on_warning();
174 /* Do not allow LOCKDEP mangling KASAN reports. */
175 lockdep_off();
176 /* Make sure we don't end up in loop. */
177 kasan_disable_current();
178 spin_lock_irqsave(&report_lock, *flags);
179 pr_err("==================================================================\n");
180}
181
182static void end_report(unsigned long *flags, void *addr)
183{
184 if (addr)
185 trace_error_report_end(ERROR_DETECTOR_KASAN,
186 (unsigned long)addr);
187 pr_err("==================================================================\n");
188 spin_unlock_irqrestore(&report_lock, *flags);
189 if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
190 check_panic_on_warn("KASAN");
191 if (kasan_arg_fault == KASAN_ARG_FAULT_PANIC)
192 panic("kasan.fault=panic set ...\n");
193 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
194 lockdep_on();
195 kasan_enable_current();
196}
197
198static void print_error_description(struct kasan_report_info *info)
199{
200 pr_err("BUG: KASAN: %s in %pS\n", info->bug_type, (void *)info->ip);
201
202 if (info->type != KASAN_REPORT_ACCESS) {
203 pr_err("Free of addr %px by task %s/%d\n",
204 info->access_addr, current->comm, task_pid_nr(current));
205 return;
206 }
207
208 if (info->access_size)
209 pr_err("%s of size %zu at addr %px by task %s/%d\n",
210 info->is_write ? "Write" : "Read", info->access_size,
211 info->access_addr, current->comm, task_pid_nr(current));
212 else
213 pr_err("%s at addr %px by task %s/%d\n",
214 info->is_write ? "Write" : "Read",
215 info->access_addr, current->comm, task_pid_nr(current));
216}
217
218static void print_track(struct kasan_track *track, const char *prefix)
219{
220 pr_err("%s by task %u:\n", prefix, track->pid);
221 if (track->stack)
222 stack_depot_print(track->stack);
223 else
224 pr_err("(stack is not available)\n");
225}
226
227static inline struct page *addr_to_page(const void *addr)
228{
229 if (virt_addr_valid(addr))
230 return virt_to_head_page(addr);
231 return NULL;
232}
233
234static void describe_object_addr(const void *addr, struct kmem_cache *cache,
235 void *object)
236{
237 unsigned long access_addr = (unsigned long)addr;
238 unsigned long object_addr = (unsigned long)object;
239 const char *rel_type;
240 int rel_bytes;
241
242 pr_err("The buggy address belongs to the object at %px\n"
243 " which belongs to the cache %s of size %d\n",
244 object, cache->name, cache->object_size);
245
246 if (access_addr < object_addr) {
247 rel_type = "to the left";
248 rel_bytes = object_addr - access_addr;
249 } else if (access_addr >= object_addr + cache->object_size) {
250 rel_type = "to the right";
251 rel_bytes = access_addr - (object_addr + cache->object_size);
252 } else {
253 rel_type = "inside";
254 rel_bytes = access_addr - object_addr;
255 }
256
257 pr_err("The buggy address is located %d bytes %s of\n"
258 " %d-byte region [%px, %px)\n",
259 rel_bytes, rel_type, cache->object_size, (void *)object_addr,
260 (void *)(object_addr + cache->object_size));
261}
262
263static void describe_object_stacks(struct kasan_report_info *info)
264{
265 if (info->alloc_track.stack) {
266 print_track(&info->alloc_track, "Allocated");
267 pr_err("\n");
268 }
269
270 if (info->free_track.stack) {
271 print_track(&info->free_track, "Freed");
272 pr_err("\n");
273 }
274
275 kasan_print_aux_stacks(info->cache, info->object);
276}
277
278static void describe_object(const void *addr, struct kasan_report_info *info)
279{
280 if (kasan_stack_collection_enabled())
281 describe_object_stacks(info);
282 describe_object_addr(addr, info->cache, info->object);
283}
284
285static inline bool kernel_or_module_addr(const void *addr)
286{
287 if (is_kernel((unsigned long)addr))
288 return true;
289 if (is_module_address((unsigned long)addr))
290 return true;
291 return false;
292}
293
294static inline bool init_task_stack_addr(const void *addr)
295{
296 return addr >= (void *)&init_thread_union.stack &&
297 (addr <= (void *)&init_thread_union.stack +
298 sizeof(init_thread_union.stack));
299}
300
301static void print_address_description(void *addr, u8 tag,
302 struct kasan_report_info *info)
303{
304 struct page *page = addr_to_page(addr);
305
306 dump_stack_lvl(KERN_ERR);
307 pr_err("\n");
308
309 if (info->cache && info->object) {
310 describe_object(addr, info);
311 pr_err("\n");
312 }
313
314 if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
315 pr_err("The buggy address belongs to the variable:\n");
316 pr_err(" %pS\n", addr);
317 pr_err("\n");
318 }
319
320 if (object_is_on_stack(addr)) {
321 /*
322 * Currently, KASAN supports printing frame information only
323 * for accesses to the task's own stack.
324 */
325 kasan_print_address_stack_frame(addr);
326 pr_err("\n");
327 }
328
329 if (is_vmalloc_addr(addr)) {
330 struct vm_struct *va = find_vm_area(addr);
331
332 if (va) {
333 pr_err("The buggy address belongs to the virtual mapping at\n"
334 " [%px, %px) created by:\n"
335 " %pS\n",
336 va->addr, va->addr + va->size, va->caller);
337 pr_err("\n");
338
339 page = vmalloc_to_page(addr);
340 }
341 }
342
343 if (page) {
344 pr_err("The buggy address belongs to the physical page:\n");
345 dump_page(page, "kasan: bad access detected");
346 pr_err("\n");
347 }
348}
349
350static bool meta_row_is_guilty(const void *row, const void *addr)
351{
352 return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW);
353}
354
355static int meta_pointer_offset(const void *row, const void *addr)
356{
357 /*
358 * Memory state around the buggy address:
359 * ff00ff00ff00ff00: 00 00 00 05 fe fe fe fe fe fe fe fe fe fe fe fe
360 * ...
361 *
362 * The length of ">ff00ff00ff00ff00: " is
363 * 3 + (BITS_PER_LONG / 8) * 2 chars.
364 * The length of each granule metadata is 2 bytes
365 * plus 1 byte for space.
366 */
367 return 3 + (BITS_PER_LONG / 8) * 2 +
368 (addr - row) / KASAN_GRANULE_SIZE * 3 + 1;
369}
370
371static void print_memory_metadata(const void *addr)
372{
373 int i;
374 void *row;
375
376 row = (void *)round_down((unsigned long)addr, META_MEM_BYTES_PER_ROW)
377 - META_ROWS_AROUND_ADDR * META_MEM_BYTES_PER_ROW;
378
379 pr_err("Memory state around the buggy address:\n");
380
381 for (i = -META_ROWS_AROUND_ADDR; i <= META_ROWS_AROUND_ADDR; i++) {
382 char buffer[4 + (BITS_PER_LONG / 8) * 2];
383 char metadata[META_BYTES_PER_ROW];
384
385 snprintf(buffer, sizeof(buffer),
386 (i == 0) ? ">%px: " : " %px: ", row);
387
388 /*
389 * We should not pass a shadow pointer to generic
390 * function, because generic functions may try to
391 * access kasan mapping for the passed address.
392 */
393 kasan_metadata_fetch_row(&metadata[0], row);
394
395 print_hex_dump(KERN_ERR, buffer,
396 DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1,
397 metadata, META_BYTES_PER_ROW, 0);
398
399 if (meta_row_is_guilty(row, addr))
400 pr_err("%*c\n", meta_pointer_offset(row, addr), '^');
401
402 row += META_MEM_BYTES_PER_ROW;
403 }
404}
405
406static void print_report(struct kasan_report_info *info)
407{
408 void *addr = kasan_reset_tag(info->access_addr);
409 u8 tag = get_tag(info->access_addr);
410
411 print_error_description(info);
412 if (addr_has_metadata(addr))
413 kasan_print_tags(tag, info->first_bad_addr);
414 pr_err("\n");
415
416 if (addr_has_metadata(addr)) {
417 print_address_description(addr, tag, info);
418 print_memory_metadata(info->first_bad_addr);
419 } else {
420 dump_stack_lvl(KERN_ERR);
421 }
422}
423
424static void complete_report_info(struct kasan_report_info *info)
425{
426 void *addr = kasan_reset_tag(info->access_addr);
427 struct slab *slab;
428
429 if (info->type == KASAN_REPORT_ACCESS)
430 info->first_bad_addr = kasan_find_first_bad_addr(
431 info->access_addr, info->access_size);
432 else
433 info->first_bad_addr = addr;
434
435 slab = kasan_addr_to_slab(addr);
436 if (slab) {
437 info->cache = slab->slab_cache;
438 info->object = nearest_obj(info->cache, slab, addr);
439 } else
440 info->cache = info->object = NULL;
441
442 switch (info->type) {
443 case KASAN_REPORT_INVALID_FREE:
444 info->bug_type = "invalid-free";
445 break;
446 case KASAN_REPORT_DOUBLE_FREE:
447 info->bug_type = "double-free";
448 break;
449 default:
450 /* bug_type filled in by kasan_complete_mode_report_info. */
451 break;
452 }
453
454 /* Fill in mode-specific report info fields. */
455 kasan_complete_mode_report_info(info);
456}
457
458void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_type type)
459{
460 unsigned long flags;
461 struct kasan_report_info info;
462
463 /*
464 * Do not check report_suppressed(), as an invalid-free cannot be
465 * caused by accessing slab metadata and thus should not be
466 * suppressed by kasan_disable/enable_current() critical sections.
467 */
468 if (unlikely(!report_enabled()))
469 return;
470
471 start_report(&flags, true);
472
473 memset(&info, 0, sizeof(info));
474 info.type = type;
475 info.access_addr = ptr;
476 info.access_size = 0;
477 info.is_write = false;
478 info.ip = ip;
479
480 complete_report_info(&info);
481
482 print_report(&info);
483
484 end_report(&flags, ptr);
485}
486
487/*
488 * kasan_report() is the only reporting function that uses
489 * user_access_save/restore(): kasan_report_invalid_free() cannot be called
490 * from a UACCESS region, and kasan_report_async() is not used on x86.
491 */
492bool kasan_report(unsigned long addr, size_t size, bool is_write,
493 unsigned long ip)
494{
495 bool ret = true;
496 void *ptr = (void *)addr;
497 unsigned long ua_flags = user_access_save();
498 unsigned long irq_flags;
499 struct kasan_report_info info;
500
501 if (unlikely(report_suppressed()) || unlikely(!report_enabled())) {
502 ret = false;
503 goto out;
504 }
505
506 start_report(&irq_flags, true);
507
508 memset(&info, 0, sizeof(info));
509 info.type = KASAN_REPORT_ACCESS;
510 info.access_addr = ptr;
511 info.access_size = size;
512 info.is_write = is_write;
513 info.ip = ip;
514
515 complete_report_info(&info);
516
517 print_report(&info);
518
519 end_report(&irq_flags, ptr);
520
521out:
522 user_access_restore(ua_flags);
523
524 return ret;
525}
526
527#ifdef CONFIG_KASAN_HW_TAGS
528void kasan_report_async(void)
529{
530 unsigned long flags;
531
532 /*
533 * Do not check report_suppressed(), as kasan_disable/enable_current()
534 * critical sections do not affect Hardware Tag-Based KASAN.
535 */
536 if (unlikely(!report_enabled()))
537 return;
538
539 start_report(&flags, false);
540 pr_err("BUG: KASAN: invalid-access\n");
541 pr_err("Asynchronous fault: no details available\n");
542 pr_err("\n");
543 dump_stack_lvl(KERN_ERR);
544 end_report(&flags, NULL);
545}
546#endif /* CONFIG_KASAN_HW_TAGS */
547
548#ifdef CONFIG_KASAN_INLINE
549/*
550 * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
551 * canonical half of the address space) cause out-of-bounds shadow memory reads
552 * before the actual access. For addresses in the low canonical half of the
553 * address space, as well as most non-canonical addresses, that out-of-bounds
554 * shadow memory access lands in the non-canonical part of the address space.
555 * Help the user figure out what the original bogus pointer was.
556 */
557void kasan_non_canonical_hook(unsigned long addr)
558{
559 unsigned long orig_addr;
560 const char *bug_type;
561
562 if (addr < KASAN_SHADOW_OFFSET)
563 return;
564
565 orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT;
566 /*
567 * For faults near the shadow address for NULL, we can be fairly certain
568 * that this is a KASAN shadow memory access.
569 * For faults that correspond to shadow for low canonical addresses, we
570 * can still be pretty sure - that shadow region is a fairly narrow
571 * chunk of the non-canonical address space.
572 * But faults that look like shadow for non-canonical addresses are a
573 * really large chunk of the address space. In that case, we still
574 * print the decoded address, but make it clear that this is not
575 * necessarily what's actually going on.
576 */
577 if (orig_addr < PAGE_SIZE)
578 bug_type = "null-ptr-deref";
579 else if (orig_addr < TASK_SIZE)
580 bug_type = "probably user-memory-access";
581 else
582 bug_type = "maybe wild-memory-access";
583 pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
584 orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1);
585}
586#endif