Loading...
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This file contains common generic and tag-based 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 * 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#include <linux/sched/task_stack.h>
32#include <linux/uaccess.h>
33
34#include <asm/sections.h>
35
36#include "kasan.h"
37#include "../slab.h"
38
39/* Shadow layout customization. */
40#define SHADOW_BYTES_PER_BLOCK 1
41#define SHADOW_BLOCKS_PER_ROW 16
42#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
43#define SHADOW_ROWS_AROUND_ADDR 2
44
45static unsigned long kasan_flags;
46
47#define KASAN_BIT_REPORTED 0
48#define KASAN_BIT_MULTI_SHOT 1
49
50bool kasan_save_enable_multi_shot(void)
51{
52 return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
53}
54EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
55
56void kasan_restore_multi_shot(bool enabled)
57{
58 if (!enabled)
59 clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
60}
61EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
62
63static int __init kasan_set_multi_shot(char *str)
64{
65 set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
66 return 1;
67}
68__setup("kasan_multi_shot", kasan_set_multi_shot);
69
70static void print_error_description(struct kasan_access_info *info)
71{
72 pr_err("BUG: KASAN: %s in %pS\n",
73 get_bug_type(info), (void *)info->ip);
74 pr_err("%s of size %zu at addr %px by task %s/%d\n",
75 info->is_write ? "Write" : "Read", info->access_size,
76 info->access_addr, current->comm, task_pid_nr(current));
77}
78
79static DEFINE_SPINLOCK(report_lock);
80
81static void start_report(unsigned long *flags)
82{
83 /*
84 * Make sure we don't end up in loop.
85 */
86 kasan_disable_current();
87 spin_lock_irqsave(&report_lock, *flags);
88 pr_err("==================================================================\n");
89}
90
91static void end_report(unsigned long *flags)
92{
93 pr_err("==================================================================\n");
94 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
95 spin_unlock_irqrestore(&report_lock, *flags);
96 if (panic_on_warn) {
97 /*
98 * This thread may hit another WARN() in the panic path.
99 * Resetting this prevents additional WARN() from panicking the
100 * system on this thread. Other threads are blocked by the
101 * panic_mutex in panic().
102 */
103 panic_on_warn = 0;
104 panic("panic_on_warn set ...\n");
105 }
106 kasan_enable_current();
107}
108
109static void print_stack(depot_stack_handle_t stack)
110{
111 unsigned long *entries;
112 unsigned int nr_entries;
113
114 nr_entries = stack_depot_fetch(stack, &entries);
115 stack_trace_print(entries, nr_entries, 0);
116}
117
118static void print_track(struct kasan_track *track, const char *prefix)
119{
120 pr_err("%s by task %u:\n", prefix, track->pid);
121 if (track->stack) {
122 print_stack(track->stack);
123 } else {
124 pr_err("(stack is not available)\n");
125 }
126}
127
128struct page *kasan_addr_to_page(const void *addr)
129{
130 if ((addr >= (void *)PAGE_OFFSET) &&
131 (addr < high_memory))
132 return virt_to_head_page(addr);
133 return NULL;
134}
135
136static void describe_object_addr(struct kmem_cache *cache, void *object,
137 const void *addr)
138{
139 unsigned long access_addr = (unsigned long)addr;
140 unsigned long object_addr = (unsigned long)object;
141 const char *rel_type;
142 int rel_bytes;
143
144 pr_err("The buggy address belongs to the object at %px\n"
145 " which belongs to the cache %s of size %d\n",
146 object, cache->name, cache->object_size);
147
148 if (!addr)
149 return;
150
151 if (access_addr < object_addr) {
152 rel_type = "to the left";
153 rel_bytes = object_addr - access_addr;
154 } else if (access_addr >= object_addr + cache->object_size) {
155 rel_type = "to the right";
156 rel_bytes = access_addr - (object_addr + cache->object_size);
157 } else {
158 rel_type = "inside";
159 rel_bytes = access_addr - object_addr;
160 }
161
162 pr_err("The buggy address is located %d bytes %s of\n"
163 " %d-byte region [%px, %px)\n",
164 rel_bytes, rel_type, cache->object_size, (void *)object_addr,
165 (void *)(object_addr + cache->object_size));
166}
167
168static void describe_object(struct kmem_cache *cache, void *object,
169 const void *addr, u8 tag)
170{
171 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
172
173 if (cache->flags & SLAB_KASAN) {
174 struct kasan_track *free_track;
175
176 print_track(&alloc_info->alloc_track, "Allocated");
177 pr_err("\n");
178 free_track = kasan_get_free_track(cache, object, tag);
179 if (free_track) {
180 print_track(free_track, "Freed");
181 pr_err("\n");
182 }
183
184#ifdef CONFIG_KASAN_GENERIC
185 if (alloc_info->aux_stack[0]) {
186 pr_err("Last call_rcu():\n");
187 print_stack(alloc_info->aux_stack[0]);
188 pr_err("\n");
189 }
190 if (alloc_info->aux_stack[1]) {
191 pr_err("Second to last call_rcu():\n");
192 print_stack(alloc_info->aux_stack[1]);
193 pr_err("\n");
194 }
195#endif
196 }
197
198 describe_object_addr(cache, object, addr);
199}
200
201static inline bool kernel_or_module_addr(const void *addr)
202{
203 if (addr >= (void *)_stext && addr < (void *)_end)
204 return true;
205 if (is_module_address((unsigned long)addr))
206 return true;
207 return false;
208}
209
210static inline bool init_task_stack_addr(const void *addr)
211{
212 return addr >= (void *)&init_thread_union.stack &&
213 (addr <= (void *)&init_thread_union.stack +
214 sizeof(init_thread_union.stack));
215}
216
217static bool __must_check tokenize_frame_descr(const char **frame_descr,
218 char *token, size_t max_tok_len,
219 unsigned long *value)
220{
221 const char *sep = strchr(*frame_descr, ' ');
222
223 if (sep == NULL)
224 sep = *frame_descr + strlen(*frame_descr);
225
226 if (token != NULL) {
227 const size_t tok_len = sep - *frame_descr;
228
229 if (tok_len + 1 > max_tok_len) {
230 pr_err("KASAN internal error: frame description too long: %s\n",
231 *frame_descr);
232 return false;
233 }
234
235 /* Copy token (+ 1 byte for '\0'). */
236 strlcpy(token, *frame_descr, tok_len + 1);
237 }
238
239 /* Advance frame_descr past separator. */
240 *frame_descr = sep + 1;
241
242 if (value != NULL && kstrtoul(token, 10, value)) {
243 pr_err("KASAN internal error: not a valid number: %s\n", token);
244 return false;
245 }
246
247 return true;
248}
249
250static void print_decoded_frame_descr(const char *frame_descr)
251{
252 /*
253 * We need to parse the following string:
254 * "n alloc_1 alloc_2 ... alloc_n"
255 * where alloc_i looks like
256 * "offset size len name"
257 * or "offset size len name:line".
258 */
259
260 char token[64];
261 unsigned long num_objects;
262
263 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
264 &num_objects))
265 return;
266
267 pr_err("\n");
268 pr_err("this frame has %lu %s:\n", num_objects,
269 num_objects == 1 ? "object" : "objects");
270
271 while (num_objects--) {
272 unsigned long offset;
273 unsigned long size;
274
275 /* access offset */
276 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
277 &offset))
278 return;
279 /* access size */
280 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
281 &size))
282 return;
283 /* name length (unused) */
284 if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL))
285 return;
286 /* object name */
287 if (!tokenize_frame_descr(&frame_descr, token, sizeof(token),
288 NULL))
289 return;
290
291 /* Strip line number; without filename it's not very helpful. */
292 strreplace(token, ':', '\0');
293
294 /* Finally, print object information. */
295 pr_err(" [%lu, %lu) '%s'", offset, offset + size, token);
296 }
297}
298
299static bool __must_check get_address_stack_frame_info(const void *addr,
300 unsigned long *offset,
301 const char **frame_descr,
302 const void **frame_pc)
303{
304 unsigned long aligned_addr;
305 unsigned long mem_ptr;
306 const u8 *shadow_bottom;
307 const u8 *shadow_ptr;
308 const unsigned long *frame;
309
310 BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP));
311
312 /*
313 * NOTE: We currently only support printing frame information for
314 * accesses to the task's own stack.
315 */
316 if (!object_is_on_stack(addr))
317 return false;
318
319 aligned_addr = round_down((unsigned long)addr, sizeof(long));
320 mem_ptr = round_down(aligned_addr, KASAN_SHADOW_SCALE_SIZE);
321 shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr);
322 shadow_bottom = kasan_mem_to_shadow(end_of_stack(current));
323
324 while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) {
325 shadow_ptr--;
326 mem_ptr -= KASAN_SHADOW_SCALE_SIZE;
327 }
328
329 while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) {
330 shadow_ptr--;
331 mem_ptr -= KASAN_SHADOW_SCALE_SIZE;
332 }
333
334 if (shadow_ptr < shadow_bottom)
335 return false;
336
337 frame = (const unsigned long *)(mem_ptr + KASAN_SHADOW_SCALE_SIZE);
338 if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) {
339 pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n",
340 frame[0]);
341 return false;
342 }
343
344 *offset = (unsigned long)addr - (unsigned long)frame;
345 *frame_descr = (const char *)frame[1];
346 *frame_pc = (void *)frame[2];
347
348 return true;
349}
350
351static void print_address_stack_frame(const void *addr)
352{
353 unsigned long offset;
354 const char *frame_descr;
355 const void *frame_pc;
356
357 if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
358 return;
359
360 if (!get_address_stack_frame_info(addr, &offset, &frame_descr,
361 &frame_pc))
362 return;
363
364 /*
365 * get_address_stack_frame_info only returns true if the given addr is
366 * on the current task's stack.
367 */
368 pr_err("\n");
369 pr_err("addr %px is located in stack of task %s/%d at offset %lu in frame:\n",
370 addr, current->comm, task_pid_nr(current), offset);
371 pr_err(" %pS\n", frame_pc);
372
373 if (!frame_descr)
374 return;
375
376 print_decoded_frame_descr(frame_descr);
377}
378
379static void print_address_description(void *addr, u8 tag)
380{
381 struct page *page = kasan_addr_to_page(addr);
382
383 dump_stack();
384 pr_err("\n");
385
386 if (page && PageSlab(page)) {
387 struct kmem_cache *cache = page->slab_cache;
388 void *object = nearest_obj(cache, page, addr);
389
390 describe_object(cache, object, addr, tag);
391 }
392
393 if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
394 pr_err("The buggy address belongs to the variable:\n");
395 pr_err(" %pS\n", addr);
396 }
397
398 if (page) {
399 pr_err("The buggy address belongs to the page:\n");
400 dump_page(page, "kasan: bad access detected");
401 }
402
403 print_address_stack_frame(addr);
404}
405
406static bool row_is_guilty(const void *row, const void *guilty)
407{
408 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
409}
410
411static int shadow_pointer_offset(const void *row, const void *shadow)
412{
413 /* The length of ">ff00ff00ff00ff00: " is
414 * 3 + (BITS_PER_LONG/8)*2 chars.
415 */
416 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
417 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
418}
419
420static void print_shadow_for_address(const void *addr)
421{
422 int i;
423 const void *shadow = kasan_mem_to_shadow(addr);
424 const void *shadow_row;
425
426 shadow_row = (void *)round_down((unsigned long)shadow,
427 SHADOW_BYTES_PER_ROW)
428 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
429
430 pr_err("Memory state around the buggy address:\n");
431
432 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
433 const void *kaddr = kasan_shadow_to_mem(shadow_row);
434 char buffer[4 + (BITS_PER_LONG/8)*2];
435 char shadow_buf[SHADOW_BYTES_PER_ROW];
436
437 snprintf(buffer, sizeof(buffer),
438 (i == 0) ? ">%px: " : " %px: ", kaddr);
439 /*
440 * We should not pass a shadow pointer to generic
441 * function, because generic functions may try to
442 * access kasan mapping for the passed address.
443 */
444 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
445 print_hex_dump(KERN_ERR, buffer,
446 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
447 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
448
449 if (row_is_guilty(shadow_row, shadow))
450 pr_err("%*c\n",
451 shadow_pointer_offset(shadow_row, shadow),
452 '^');
453
454 shadow_row += SHADOW_BYTES_PER_ROW;
455 }
456}
457
458static bool report_enabled(void)
459{
460 if (current->kasan_depth)
461 return false;
462 if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
463 return true;
464 return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
465}
466
467void kasan_report_invalid_free(void *object, unsigned long ip)
468{
469 unsigned long flags;
470 u8 tag = get_tag(object);
471
472 object = reset_tag(object);
473 start_report(&flags);
474 pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
475 print_tags(tag, object);
476 pr_err("\n");
477 print_address_description(object, tag);
478 pr_err("\n");
479 print_shadow_for_address(object);
480 end_report(&flags);
481}
482
483static void __kasan_report(unsigned long addr, size_t size, bool is_write,
484 unsigned long ip)
485{
486 struct kasan_access_info info;
487 void *tagged_addr;
488 void *untagged_addr;
489 unsigned long flags;
490
491 disable_trace_on_warning();
492
493 tagged_addr = (void *)addr;
494 untagged_addr = reset_tag(tagged_addr);
495
496 info.access_addr = tagged_addr;
497 if (addr_has_shadow(untagged_addr))
498 info.first_bad_addr = find_first_bad_addr(tagged_addr, size);
499 else
500 info.first_bad_addr = untagged_addr;
501 info.access_size = size;
502 info.is_write = is_write;
503 info.ip = ip;
504
505 start_report(&flags);
506
507 print_error_description(&info);
508 if (addr_has_shadow(untagged_addr))
509 print_tags(get_tag(tagged_addr), info.first_bad_addr);
510 pr_err("\n");
511
512 if (addr_has_shadow(untagged_addr)) {
513 print_address_description(untagged_addr, get_tag(tagged_addr));
514 pr_err("\n");
515 print_shadow_for_address(info.first_bad_addr);
516 } else {
517 dump_stack();
518 }
519
520 end_report(&flags);
521}
522
523bool kasan_report(unsigned long addr, size_t size, bool is_write,
524 unsigned long ip)
525{
526 unsigned long flags = user_access_save();
527 bool ret = false;
528
529 if (likely(report_enabled())) {
530 __kasan_report(addr, size, is_write, ip);
531 ret = true;
532 }
533
534 user_access_restore(flags);
535
536 return ret;
537}
538
539#ifdef CONFIG_KASAN_INLINE
540/*
541 * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
542 * canonical half of the address space) cause out-of-bounds shadow memory reads
543 * before the actual access. For addresses in the low canonical half of the
544 * address space, as well as most non-canonical addresses, that out-of-bounds
545 * shadow memory access lands in the non-canonical part of the address space.
546 * Help the user figure out what the original bogus pointer was.
547 */
548void kasan_non_canonical_hook(unsigned long addr)
549{
550 unsigned long orig_addr;
551 const char *bug_type;
552
553 if (addr < KASAN_SHADOW_OFFSET)
554 return;
555
556 orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT;
557 /*
558 * For faults near the shadow address for NULL, we can be fairly certain
559 * that this is a KASAN shadow memory access.
560 * For faults that correspond to shadow for low canonical addresses, we
561 * can still be pretty sure - that shadow region is a fairly narrow
562 * chunk of the non-canonical address space.
563 * But faults that look like shadow for non-canonical addresses are a
564 * really large chunk of the address space. In that case, we still
565 * print the decoded address, but make it clear that this is not
566 * necessarily what's actually going on.
567 */
568 if (orig_addr < PAGE_SIZE)
569 bug_type = "null-ptr-deref";
570 else if (orig_addr < TASK_SIZE)
571 bug_type = "probably user-memory-access";
572 else
573 bug_type = "maybe wild-memory-access";
574 pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
575 orig_addr, orig_addr + KASAN_SHADOW_MASK);
576}
577#endif
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