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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 <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/stackdepot.h>
22#include <linux/stacktrace.h>
23#include <linux/string.h>
24#include <linux/types.h>
25#include <linux/kasan.h>
26#include <linux/module.h>
27
28#include <asm/sections.h>
29
30#include "kasan.h"
31#include "../slab.h"
32
33/* Shadow layout customization. */
34#define SHADOW_BYTES_PER_BLOCK 1
35#define SHADOW_BLOCKS_PER_ROW 16
36#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
37#define SHADOW_ROWS_AROUND_ADDR 2
38
39static const void *find_first_bad_addr(const void *addr, size_t size)
40{
41 u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
42 const void *first_bad_addr = addr;
43
44 while (!shadow_val && first_bad_addr < addr + size) {
45 first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
46 shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
47 }
48 return first_bad_addr;
49}
50
51static void print_error_description(struct kasan_access_info *info)
52{
53 const char *bug_type = "unknown-crash";
54 u8 *shadow_addr;
55
56 info->first_bad_addr = find_first_bad_addr(info->access_addr,
57 info->access_size);
58
59 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
60
61 /*
62 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
63 * at the next shadow byte to determine the type of the bad access.
64 */
65 if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
66 shadow_addr++;
67
68 switch (*shadow_addr) {
69 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
70 /*
71 * In theory it's still possible to see these shadow values
72 * due to a data race in the kernel code.
73 */
74 bug_type = "out-of-bounds";
75 break;
76 case KASAN_PAGE_REDZONE:
77 case KASAN_KMALLOC_REDZONE:
78 bug_type = "slab-out-of-bounds";
79 break;
80 case KASAN_GLOBAL_REDZONE:
81 bug_type = "global-out-of-bounds";
82 break;
83 case KASAN_STACK_LEFT:
84 case KASAN_STACK_MID:
85 case KASAN_STACK_RIGHT:
86 case KASAN_STACK_PARTIAL:
87 bug_type = "stack-out-of-bounds";
88 break;
89 case KASAN_FREE_PAGE:
90 case KASAN_KMALLOC_FREE:
91 bug_type = "use-after-free";
92 break;
93 }
94
95 pr_err("BUG: KASAN: %s in %pS at addr %p\n",
96 bug_type, (void *)info->ip,
97 info->access_addr);
98 pr_err("%s of size %zu by task %s/%d\n",
99 info->is_write ? "Write" : "Read",
100 info->access_size, current->comm, task_pid_nr(current));
101}
102
103static inline bool kernel_or_module_addr(const void *addr)
104{
105 if (addr >= (void *)_stext && addr < (void *)_end)
106 return true;
107 if (is_module_address((unsigned long)addr))
108 return true;
109 return false;
110}
111
112static inline bool init_task_stack_addr(const void *addr)
113{
114 return addr >= (void *)&init_thread_union.stack &&
115 (addr <= (void *)&init_thread_union.stack +
116 sizeof(init_thread_union.stack));
117}
118
119#ifdef CONFIG_SLAB
120static void print_track(struct kasan_track *track)
121{
122 pr_err("PID = %u\n", track->pid);
123 if (track->stack) {
124 struct stack_trace trace;
125
126 depot_fetch_stack(track->stack, &trace);
127 print_stack_trace(&trace, 0);
128 } else {
129 pr_err("(stack is not available)\n");
130 }
131}
132
133static void object_err(struct kmem_cache *cache, struct page *page,
134 void *object, char *unused_reason)
135{
136 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
137 struct kasan_free_meta *free_info;
138
139 dump_stack();
140 pr_err("Object at %p, in cache %s\n", object, cache->name);
141 if (!(cache->flags & SLAB_KASAN))
142 return;
143 switch (alloc_info->state) {
144 case KASAN_STATE_INIT:
145 pr_err("Object not allocated yet\n");
146 break;
147 case KASAN_STATE_ALLOC:
148 pr_err("Object allocated with size %u bytes.\n",
149 alloc_info->alloc_size);
150 pr_err("Allocation:\n");
151 print_track(&alloc_info->track);
152 break;
153 case KASAN_STATE_FREE:
154 pr_err("Object freed, allocated with size %u bytes\n",
155 alloc_info->alloc_size);
156 free_info = get_free_info(cache, object);
157 pr_err("Allocation:\n");
158 print_track(&alloc_info->track);
159 pr_err("Deallocation:\n");
160 print_track(&free_info->track);
161 break;
162 }
163}
164#endif
165
166static void print_address_description(struct kasan_access_info *info)
167{
168 const void *addr = info->access_addr;
169
170 if ((addr >= (void *)PAGE_OFFSET) &&
171 (addr < high_memory)) {
172 struct page *page = virt_to_head_page(addr);
173
174 if (PageSlab(page)) {
175 void *object;
176 struct kmem_cache *cache = page->slab_cache;
177 object = nearest_obj(cache, page,
178 (void *)info->access_addr);
179 object_err(cache, page, object,
180 "kasan: bad access detected");
181 return;
182 }
183 dump_page(page, "kasan: bad access detected");
184 }
185
186 if (kernel_or_module_addr(addr)) {
187 if (!init_task_stack_addr(addr))
188 pr_err("Address belongs to variable %pS\n", addr);
189 }
190 dump_stack();
191}
192
193static bool row_is_guilty(const void *row, const void *guilty)
194{
195 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
196}
197
198static int shadow_pointer_offset(const void *row, const void *shadow)
199{
200 /* The length of ">ff00ff00ff00ff00: " is
201 * 3 + (BITS_PER_LONG/8)*2 chars.
202 */
203 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
204 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
205}
206
207static void print_shadow_for_address(const void *addr)
208{
209 int i;
210 const void *shadow = kasan_mem_to_shadow(addr);
211 const void *shadow_row;
212
213 shadow_row = (void *)round_down((unsigned long)shadow,
214 SHADOW_BYTES_PER_ROW)
215 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
216
217 pr_err("Memory state around the buggy address:\n");
218
219 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
220 const void *kaddr = kasan_shadow_to_mem(shadow_row);
221 char buffer[4 + (BITS_PER_LONG/8)*2];
222 char shadow_buf[SHADOW_BYTES_PER_ROW];
223
224 snprintf(buffer, sizeof(buffer),
225 (i == 0) ? ">%p: " : " %p: ", kaddr);
226 /*
227 * We should not pass a shadow pointer to generic
228 * function, because generic functions may try to
229 * access kasan mapping for the passed address.
230 */
231 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
232 print_hex_dump(KERN_ERR, buffer,
233 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
234 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
235
236 if (row_is_guilty(shadow_row, shadow))
237 pr_err("%*c\n",
238 shadow_pointer_offset(shadow_row, shadow),
239 '^');
240
241 shadow_row += SHADOW_BYTES_PER_ROW;
242 }
243}
244
245static DEFINE_SPINLOCK(report_lock);
246
247static void kasan_report_error(struct kasan_access_info *info)
248{
249 unsigned long flags;
250 const char *bug_type;
251
252 /*
253 * Make sure we don't end up in loop.
254 */
255 kasan_disable_current();
256 spin_lock_irqsave(&report_lock, flags);
257 pr_err("==================================================================\n");
258 if (info->access_addr <
259 kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
260 if ((unsigned long)info->access_addr < PAGE_SIZE)
261 bug_type = "null-ptr-deref";
262 else if ((unsigned long)info->access_addr < TASK_SIZE)
263 bug_type = "user-memory-access";
264 else
265 bug_type = "wild-memory-access";
266 pr_err("BUG: KASAN: %s on address %p\n",
267 bug_type, info->access_addr);
268 pr_err("%s of size %zu by task %s/%d\n",
269 info->is_write ? "Write" : "Read",
270 info->access_size, current->comm,
271 task_pid_nr(current));
272 dump_stack();
273 } else {
274 print_error_description(info);
275 print_address_description(info);
276 print_shadow_for_address(info->first_bad_addr);
277 }
278 pr_err("==================================================================\n");
279 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
280 spin_unlock_irqrestore(&report_lock, flags);
281 kasan_enable_current();
282}
283
284void kasan_report(unsigned long addr, size_t size,
285 bool is_write, unsigned long ip)
286{
287 struct kasan_access_info info;
288
289 if (likely(!kasan_report_enabled()))
290 return;
291
292 info.access_addr = (void *)addr;
293 info.access_size = size;
294 info.is_write = is_write;
295 info.ip = ip;
296
297 kasan_report_error(&info);
298}
299
300
301#define DEFINE_ASAN_REPORT_LOAD(size) \
302void __asan_report_load##size##_noabort(unsigned long addr) \
303{ \
304 kasan_report(addr, size, false, _RET_IP_); \
305} \
306EXPORT_SYMBOL(__asan_report_load##size##_noabort)
307
308#define DEFINE_ASAN_REPORT_STORE(size) \
309void __asan_report_store##size##_noabort(unsigned long addr) \
310{ \
311 kasan_report(addr, size, true, _RET_IP_); \
312} \
313EXPORT_SYMBOL(__asan_report_store##size##_noabort)
314
315DEFINE_ASAN_REPORT_LOAD(1);
316DEFINE_ASAN_REPORT_LOAD(2);
317DEFINE_ASAN_REPORT_LOAD(4);
318DEFINE_ASAN_REPORT_LOAD(8);
319DEFINE_ASAN_REPORT_LOAD(16);
320DEFINE_ASAN_REPORT_STORE(1);
321DEFINE_ASAN_REPORT_STORE(2);
322DEFINE_ASAN_REPORT_STORE(4);
323DEFINE_ASAN_REPORT_STORE(8);
324DEFINE_ASAN_REPORT_STORE(16);
325
326void __asan_report_load_n_noabort(unsigned long addr, size_t size)
327{
328 kasan_report(addr, size, false, _RET_IP_);
329}
330EXPORT_SYMBOL(__asan_report_load_n_noabort);
331
332void __asan_report_store_n_noabort(unsigned long addr, size_t size)
333{
334 kasan_report(addr, size, true, _RET_IP_);
335}
336EXPORT_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 <kunit/visibility.h>
14#include <linux/bitops.h>
15#include <linux/ftrace.h>
16#include <linux/init.h>
17#include <linux/kernel.h>
18#include <linux/lockdep.h>
19#include <linux/mm.h>
20#include <linux/printk.h>
21#include <linux/sched.h>
22#include <linux/slab.h>
23#include <linux/stackdepot.h>
24#include <linux/stacktrace.h>
25#include <linux/string.h>
26#include <linux/types.h>
27#include <linux/vmalloc.h>
28#include <linux/kasan.h>
29#include <linux/module.h>
30#include <linux/sched/task_stack.h>
31#include <linux/uaccess.h>
32#include <trace/events/error_report.h>
33
34#include <asm/sections.h>
35
36#include "kasan.h"
37#include "../slab.h"
38
39static unsigned long kasan_flags;
40
41#define KASAN_BIT_REPORTED 0
42#define KASAN_BIT_MULTI_SHOT 1
43
44enum kasan_arg_fault {
45 KASAN_ARG_FAULT_DEFAULT,
46 KASAN_ARG_FAULT_REPORT,
47 KASAN_ARG_FAULT_PANIC,
48 KASAN_ARG_FAULT_PANIC_ON_WRITE,
49};
50
51static enum kasan_arg_fault kasan_arg_fault __ro_after_init = KASAN_ARG_FAULT_DEFAULT;
52
53/* kasan.fault=report/panic */
54static int __init early_kasan_fault(char *arg)
55{
56 if (!arg)
57 return -EINVAL;
58
59 if (!strcmp(arg, "report"))
60 kasan_arg_fault = KASAN_ARG_FAULT_REPORT;
61 else if (!strcmp(arg, "panic"))
62 kasan_arg_fault = KASAN_ARG_FAULT_PANIC;
63 else if (!strcmp(arg, "panic_on_write"))
64 kasan_arg_fault = KASAN_ARG_FAULT_PANIC_ON_WRITE;
65 else
66 return -EINVAL;
67
68 return 0;
69}
70early_param("kasan.fault", early_kasan_fault);
71
72static int __init kasan_set_multi_shot(char *str)
73{
74 set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
75 return 1;
76}
77__setup("kasan_multi_shot", kasan_set_multi_shot);
78
79/*
80 * This function is used to check whether KASAN reports are suppressed for
81 * software KASAN modes via kasan_disable/enable_current() critical sections.
82 *
83 * This is done to avoid:
84 * 1. False-positive reports when accessing slab metadata,
85 * 2. Deadlocking when poisoned memory is accessed by the reporting code.
86 *
87 * Hardware Tag-Based KASAN instead relies on:
88 * For #1: Resetting tags via kasan_reset_tag().
89 * For #2: Suppression of tag checks via CPU, see report_suppress_start/end().
90 */
91static bool report_suppressed_sw(void)
92{
93#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
94 if (current->kasan_depth)
95 return true;
96#endif
97 return false;
98}
99
100static void report_suppress_start(void)
101{
102#ifdef CONFIG_KASAN_HW_TAGS
103 /*
104 * Disable preemption for the duration of printing a KASAN report, as
105 * hw_suppress_tag_checks_start() disables checks on the current CPU.
106 */
107 preempt_disable();
108 hw_suppress_tag_checks_start();
109#else
110 kasan_disable_current();
111#endif
112}
113
114static void report_suppress_stop(void)
115{
116#ifdef CONFIG_KASAN_HW_TAGS
117 hw_suppress_tag_checks_stop();
118 preempt_enable();
119#else
120 kasan_enable_current();
121#endif
122}
123
124/*
125 * Used to avoid reporting more than one KASAN bug unless kasan_multi_shot
126 * is enabled. Note that KASAN tests effectively enable kasan_multi_shot
127 * for their duration.
128 */
129static bool report_enabled(void)
130{
131 if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
132 return true;
133 return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
134}
135
136#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
137
138VISIBLE_IF_KUNIT bool kasan_save_enable_multi_shot(void)
139{
140 return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
141}
142EXPORT_SYMBOL_IF_KUNIT(kasan_save_enable_multi_shot);
143
144VISIBLE_IF_KUNIT void kasan_restore_multi_shot(bool enabled)
145{
146 if (!enabled)
147 clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
148}
149EXPORT_SYMBOL_IF_KUNIT(kasan_restore_multi_shot);
150
151#endif
152
153#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
154
155/*
156 * Whether the KASAN KUnit test suite is currently being executed.
157 * Updated in kasan_test.c.
158 */
159static bool kasan_kunit_executing;
160
161VISIBLE_IF_KUNIT void kasan_kunit_test_suite_start(void)
162{
163 WRITE_ONCE(kasan_kunit_executing, true);
164}
165EXPORT_SYMBOL_IF_KUNIT(kasan_kunit_test_suite_start);
166
167VISIBLE_IF_KUNIT void kasan_kunit_test_suite_end(void)
168{
169 WRITE_ONCE(kasan_kunit_executing, false);
170}
171EXPORT_SYMBOL_IF_KUNIT(kasan_kunit_test_suite_end);
172
173static bool kasan_kunit_test_suite_executing(void)
174{
175 return READ_ONCE(kasan_kunit_executing);
176}
177
178#else /* CONFIG_KASAN_KUNIT_TEST */
179
180static inline bool kasan_kunit_test_suite_executing(void) { return false; }
181
182#endif /* CONFIG_KASAN_KUNIT_TEST */
183
184#if IS_ENABLED(CONFIG_KUNIT)
185
186static void fail_non_kasan_kunit_test(void)
187{
188 struct kunit *test;
189
190 if (kasan_kunit_test_suite_executing())
191 return;
192
193 test = current->kunit_test;
194 if (test)
195 kunit_set_failure(test);
196}
197
198#else /* CONFIG_KUNIT */
199
200static inline void fail_non_kasan_kunit_test(void) { }
201
202#endif /* CONFIG_KUNIT */
203
204static DEFINE_RAW_SPINLOCK(report_lock);
205
206static void start_report(unsigned long *flags, bool sync)
207{
208 fail_non_kasan_kunit_test();
209 /* Respect the /proc/sys/kernel/traceoff_on_warning interface. */
210 disable_trace_on_warning();
211 /* Do not allow LOCKDEP mangling KASAN reports. */
212 lockdep_off();
213 /* Make sure we don't end up in loop. */
214 report_suppress_start();
215 raw_spin_lock_irqsave(&report_lock, *flags);
216 pr_err("==================================================================\n");
217}
218
219static void end_report(unsigned long *flags, const void *addr, bool is_write)
220{
221 if (addr)
222 trace_error_report_end(ERROR_DETECTOR_KASAN,
223 (unsigned long)addr);
224 pr_err("==================================================================\n");
225 raw_spin_unlock_irqrestore(&report_lock, *flags);
226 if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
227 check_panic_on_warn("KASAN");
228 switch (kasan_arg_fault) {
229 case KASAN_ARG_FAULT_DEFAULT:
230 case KASAN_ARG_FAULT_REPORT:
231 break;
232 case KASAN_ARG_FAULT_PANIC:
233 panic("kasan.fault=panic set ...\n");
234 break;
235 case KASAN_ARG_FAULT_PANIC_ON_WRITE:
236 if (is_write)
237 panic("kasan.fault=panic_on_write set ...\n");
238 break;
239 }
240 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
241 lockdep_on();
242 report_suppress_stop();
243}
244
245static void print_error_description(struct kasan_report_info *info)
246{
247 pr_err("BUG: KASAN: %s in %pS\n", info->bug_type, (void *)info->ip);
248
249 if (info->type != KASAN_REPORT_ACCESS) {
250 pr_err("Free of addr %px by task %s/%d\n",
251 info->access_addr, current->comm, task_pid_nr(current));
252 return;
253 }
254
255 if (info->access_size)
256 pr_err("%s of size %zu at addr %px by task %s/%d\n",
257 info->is_write ? "Write" : "Read", info->access_size,
258 info->access_addr, current->comm, task_pid_nr(current));
259 else
260 pr_err("%s at addr %px by task %s/%d\n",
261 info->is_write ? "Write" : "Read",
262 info->access_addr, current->comm, task_pid_nr(current));
263}
264
265static void print_track(struct kasan_track *track, const char *prefix)
266{
267#ifdef CONFIG_KASAN_EXTRA_INFO
268 u64 ts_nsec = track->timestamp;
269 unsigned long rem_usec;
270
271 ts_nsec <<= 9;
272 rem_usec = do_div(ts_nsec, NSEC_PER_SEC) / 1000;
273
274 pr_err("%s by task %u on cpu %d at %lu.%06lus:\n",
275 prefix, track->pid, track->cpu,
276 (unsigned long)ts_nsec, rem_usec);
277#else
278 pr_err("%s by task %u:\n", prefix, track->pid);
279#endif /* CONFIG_KASAN_EXTRA_INFO */
280 if (track->stack)
281 stack_depot_print(track->stack);
282 else
283 pr_err("(stack is not available)\n");
284}
285
286static inline struct page *addr_to_page(const void *addr)
287{
288 if (virt_addr_valid(addr))
289 return virt_to_head_page(addr);
290 return NULL;
291}
292
293static void describe_object_addr(const void *addr, struct kasan_report_info *info)
294{
295 unsigned long access_addr = (unsigned long)addr;
296 unsigned long object_addr = (unsigned long)info->object;
297 const char *rel_type, *region_state = "";
298 int rel_bytes;
299
300 pr_err("The buggy address belongs to the object at %px\n"
301 " which belongs to the cache %s of size %d\n",
302 info->object, info->cache->name, info->cache->object_size);
303
304 if (access_addr < object_addr) {
305 rel_type = "to the left";
306 rel_bytes = object_addr - access_addr;
307 } else if (access_addr >= object_addr + info->alloc_size) {
308 rel_type = "to the right";
309 rel_bytes = access_addr - (object_addr + info->alloc_size);
310 } else {
311 rel_type = "inside";
312 rel_bytes = access_addr - object_addr;
313 }
314
315 /*
316 * Tag-Based modes use the stack ring to infer the bug type, but the
317 * memory region state description is generated based on the metadata.
318 * Thus, defining the region state as below can contradict the metadata.
319 * Fixing this requires further improvements, so only infer the state
320 * for the Generic mode.
321 */
322 if (IS_ENABLED(CONFIG_KASAN_GENERIC)) {
323 if (strcmp(info->bug_type, "slab-out-of-bounds") == 0)
324 region_state = "allocated ";
325 else if (strcmp(info->bug_type, "slab-use-after-free") == 0)
326 region_state = "freed ";
327 }
328
329 pr_err("The buggy address is located %d bytes %s of\n"
330 " %s%zu-byte region [%px, %px)\n",
331 rel_bytes, rel_type, region_state, info->alloc_size,
332 (void *)object_addr, (void *)(object_addr + info->alloc_size));
333}
334
335static void describe_object_stacks(struct kasan_report_info *info)
336{
337 if (info->alloc_track.stack) {
338 print_track(&info->alloc_track, "Allocated");
339 pr_err("\n");
340 }
341
342 if (info->free_track.stack) {
343 print_track(&info->free_track, "Freed");
344 pr_err("\n");
345 }
346
347 kasan_print_aux_stacks(info->cache, info->object);
348}
349
350static void describe_object(const void *addr, struct kasan_report_info *info)
351{
352 if (kasan_stack_collection_enabled())
353 describe_object_stacks(info);
354 describe_object_addr(addr, info);
355}
356
357static inline bool kernel_or_module_addr(const void *addr)
358{
359 if (is_kernel((unsigned long)addr))
360 return true;
361 if (is_module_address((unsigned long)addr))
362 return true;
363 return false;
364}
365
366static inline bool init_task_stack_addr(const void *addr)
367{
368 return addr >= (void *)&init_thread_union.stack &&
369 (addr <= (void *)&init_thread_union.stack +
370 sizeof(init_thread_union.stack));
371}
372
373static void print_address_description(void *addr, u8 tag,
374 struct kasan_report_info *info)
375{
376 struct page *page = addr_to_page(addr);
377
378 dump_stack_lvl(KERN_ERR);
379 pr_err("\n");
380
381 if (info->cache && info->object) {
382 describe_object(addr, info);
383 pr_err("\n");
384 }
385
386 if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
387 pr_err("The buggy address belongs to the variable:\n");
388 pr_err(" %pS\n", addr);
389 pr_err("\n");
390 }
391
392 if (object_is_on_stack(addr)) {
393 /*
394 * Currently, KASAN supports printing frame information only
395 * for accesses to the task's own stack.
396 */
397 kasan_print_address_stack_frame(addr);
398 pr_err("\n");
399 }
400
401 if (is_vmalloc_addr(addr)) {
402 struct vm_struct *va = find_vm_area(addr);
403
404 if (va) {
405 pr_err("The buggy address belongs to the virtual mapping at\n"
406 " [%px, %px) created by:\n"
407 " %pS\n",
408 va->addr, va->addr + va->size, va->caller);
409 pr_err("\n");
410
411 page = vmalloc_to_page(addr);
412 }
413 }
414
415 if (page) {
416 pr_err("The buggy address belongs to the physical page:\n");
417 dump_page(page, "kasan: bad access detected");
418 pr_err("\n");
419 }
420}
421
422static bool meta_row_is_guilty(const void *row, const void *addr)
423{
424 return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW);
425}
426
427static int meta_pointer_offset(const void *row, const void *addr)
428{
429 /*
430 * Memory state around the buggy address:
431 * ff00ff00ff00ff00: 00 00 00 05 fe fe fe fe fe fe fe fe fe fe fe fe
432 * ...
433 *
434 * The length of ">ff00ff00ff00ff00: " is
435 * 3 + (BITS_PER_LONG / 8) * 2 chars.
436 * The length of each granule metadata is 2 bytes
437 * plus 1 byte for space.
438 */
439 return 3 + (BITS_PER_LONG / 8) * 2 +
440 (addr - row) / KASAN_GRANULE_SIZE * 3 + 1;
441}
442
443static void print_memory_metadata(const void *addr)
444{
445 int i;
446 void *row;
447
448 row = (void *)round_down((unsigned long)addr, META_MEM_BYTES_PER_ROW)
449 - META_ROWS_AROUND_ADDR * META_MEM_BYTES_PER_ROW;
450
451 pr_err("Memory state around the buggy address:\n");
452
453 for (i = -META_ROWS_AROUND_ADDR; i <= META_ROWS_AROUND_ADDR; i++) {
454 char buffer[4 + (BITS_PER_LONG / 8) * 2];
455 char metadata[META_BYTES_PER_ROW];
456
457 snprintf(buffer, sizeof(buffer),
458 (i == 0) ? ">%px: " : " %px: ", row);
459
460 /*
461 * We should not pass a shadow pointer to generic
462 * function, because generic functions may try to
463 * access kasan mapping for the passed address.
464 */
465 kasan_metadata_fetch_row(&metadata[0], row);
466
467 print_hex_dump(KERN_ERR, buffer,
468 DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1,
469 metadata, META_BYTES_PER_ROW, 0);
470
471 if (meta_row_is_guilty(row, addr))
472 pr_err("%*c\n", meta_pointer_offset(row, addr), '^');
473
474 row += META_MEM_BYTES_PER_ROW;
475 }
476}
477
478static void print_report(struct kasan_report_info *info)
479{
480 void *addr = kasan_reset_tag((void *)info->access_addr);
481 u8 tag = get_tag((void *)info->access_addr);
482
483 print_error_description(info);
484 if (addr_has_metadata(addr))
485 kasan_print_tags(tag, info->first_bad_addr);
486 pr_err("\n");
487
488 if (addr_has_metadata(addr)) {
489 print_address_description(addr, tag, info);
490 print_memory_metadata(info->first_bad_addr);
491 } else {
492 dump_stack_lvl(KERN_ERR);
493 }
494}
495
496static void complete_report_info(struct kasan_report_info *info)
497{
498 void *addr = kasan_reset_tag((void *)info->access_addr);
499 struct slab *slab;
500
501 if (info->type == KASAN_REPORT_ACCESS)
502 info->first_bad_addr = kasan_find_first_bad_addr(
503 (void *)info->access_addr, info->access_size);
504 else
505 info->first_bad_addr = addr;
506
507 slab = kasan_addr_to_slab(addr);
508 if (slab) {
509 info->cache = slab->slab_cache;
510 info->object = nearest_obj(info->cache, slab, addr);
511
512 /* Try to determine allocation size based on the metadata. */
513 info->alloc_size = kasan_get_alloc_size(info->object, info->cache);
514 /* Fallback to the object size if failed. */
515 if (!info->alloc_size)
516 info->alloc_size = info->cache->object_size;
517 } else
518 info->cache = info->object = NULL;
519
520 switch (info->type) {
521 case KASAN_REPORT_INVALID_FREE:
522 info->bug_type = "invalid-free";
523 break;
524 case KASAN_REPORT_DOUBLE_FREE:
525 info->bug_type = "double-free";
526 break;
527 default:
528 /* bug_type filled in by kasan_complete_mode_report_info. */
529 break;
530 }
531
532 /* Fill in mode-specific report info fields. */
533 kasan_complete_mode_report_info(info);
534}
535
536void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_type type)
537{
538 unsigned long flags;
539 struct kasan_report_info info;
540
541 /*
542 * Do not check report_suppressed_sw(), as an invalid-free cannot be
543 * caused by accessing poisoned memory and thus should not be suppressed
544 * by kasan_disable/enable_current() critical sections.
545 *
546 * Note that for Hardware Tag-Based KASAN, kasan_report_invalid_free()
547 * is triggered by explicit tag checks and not by the ones performed by
548 * the CPU. Thus, reporting invalid-free is not suppressed as well.
549 */
550 if (unlikely(!report_enabled()))
551 return;
552
553 start_report(&flags, true);
554
555 __memset(&info, 0, sizeof(info));
556 info.type = type;
557 info.access_addr = ptr;
558 info.access_size = 0;
559 info.is_write = false;
560 info.ip = ip;
561
562 complete_report_info(&info);
563
564 print_report(&info);
565
566 /*
567 * Invalid free is considered a "write" since the allocator's metadata
568 * updates involves writes.
569 */
570 end_report(&flags, ptr, true);
571}
572
573/*
574 * kasan_report() is the only reporting function that uses
575 * user_access_save/restore(): kasan_report_invalid_free() cannot be called
576 * from a UACCESS region, and kasan_report_async() is not used on x86.
577 */
578bool kasan_report(const void *addr, size_t size, bool is_write,
579 unsigned long ip)
580{
581 bool ret = true;
582 unsigned long ua_flags = user_access_save();
583 unsigned long irq_flags;
584 struct kasan_report_info info;
585
586 if (unlikely(report_suppressed_sw()) || unlikely(!report_enabled())) {
587 ret = false;
588 goto out;
589 }
590
591 start_report(&irq_flags, true);
592
593 __memset(&info, 0, sizeof(info));
594 info.type = KASAN_REPORT_ACCESS;
595 info.access_addr = addr;
596 info.access_size = size;
597 info.is_write = is_write;
598 info.ip = ip;
599
600 complete_report_info(&info);
601
602 print_report(&info);
603
604 end_report(&irq_flags, (void *)addr, is_write);
605
606out:
607 user_access_restore(ua_flags);
608
609 return ret;
610}
611
612#ifdef CONFIG_KASAN_HW_TAGS
613void kasan_report_async(void)
614{
615 unsigned long flags;
616
617 /*
618 * Do not check report_suppressed_sw(), as
619 * kasan_disable/enable_current() critical sections do not affect
620 * Hardware Tag-Based KASAN.
621 */
622 if (unlikely(!report_enabled()))
623 return;
624
625 start_report(&flags, false);
626 pr_err("BUG: KASAN: invalid-access\n");
627 pr_err("Asynchronous fault: no details available\n");
628 pr_err("\n");
629 dump_stack_lvl(KERN_ERR);
630 /*
631 * Conservatively set is_write=true, because no details are available.
632 * In this mode, kasan.fault=panic_on_write is like kasan.fault=panic.
633 */
634 end_report(&flags, NULL, true);
635}
636#endif /* CONFIG_KASAN_HW_TAGS */
637
638#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
639/*
640 * With compiler-based KASAN modes, accesses to bogus pointers (outside of the
641 * mapped kernel address space regions) cause faults when KASAN tries to check
642 * the shadow memory before the actual memory access. This results in cryptic
643 * GPF reports, which are hard for users to interpret. This hook helps users to
644 * figure out what the original bogus pointer was.
645 */
646void kasan_non_canonical_hook(unsigned long addr)
647{
648 unsigned long orig_addr;
649 const char *bug_type;
650
651 /*
652 * All addresses that came as a result of the memory-to-shadow mapping
653 * (even for bogus pointers) must be >= KASAN_SHADOW_OFFSET.
654 */
655 if (addr < KASAN_SHADOW_OFFSET)
656 return;
657
658 orig_addr = (unsigned long)kasan_shadow_to_mem((void *)addr);
659
660 /*
661 * For faults near the shadow address for NULL, we can be fairly certain
662 * that this is a KASAN shadow memory access.
663 * For faults that correspond to the shadow for low or high canonical
664 * addresses, we can still be pretty sure: these shadow regions are a
665 * fairly narrow chunk of the address space.
666 * But the shadow for non-canonical addresses is a really large chunk
667 * of the address space. For this case, we still print the decoded
668 * address, but make it clear that this is not necessarily what's
669 * actually going on.
670 */
671 if (orig_addr < PAGE_SIZE)
672 bug_type = "null-ptr-deref";
673 else if (orig_addr < TASK_SIZE)
674 bug_type = "probably user-memory-access";
675 else if (addr_in_shadow((void *)addr))
676 bug_type = "probably wild-memory-access";
677 else
678 bug_type = "maybe wild-memory-access";
679 pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
680 orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1);
681}
682#endif