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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/vmalloc.h>
27#include <linux/kasan.h>
28#include <linux/module.h>
29#include <linux/sched/task_stack.h>
30#include <linux/uaccess.h>
31#include <trace/events/error_report.h>
32
33#include <asm/sections.h>
34
35#include "kasan.h"
36#include "../slab.h"
37
38static unsigned long kasan_flags;
39
40#define KASAN_BIT_REPORTED 0
41#define KASAN_BIT_MULTI_SHOT 1
42
43enum kasan_arg_fault {
44 KASAN_ARG_FAULT_DEFAULT,
45 KASAN_ARG_FAULT_REPORT,
46 KASAN_ARG_FAULT_PANIC,
47 KASAN_ARG_FAULT_PANIC_ON_WRITE,
48};
49
50static enum kasan_arg_fault kasan_arg_fault __ro_after_init = KASAN_ARG_FAULT_DEFAULT;
51
52/* kasan.fault=report/panic */
53static int __init early_kasan_fault(char *arg)
54{
55 if (!arg)
56 return -EINVAL;
57
58 if (!strcmp(arg, "report"))
59 kasan_arg_fault = KASAN_ARG_FAULT_REPORT;
60 else if (!strcmp(arg, "panic"))
61 kasan_arg_fault = KASAN_ARG_FAULT_PANIC;
62 else if (!strcmp(arg, "panic_on_write"))
63 kasan_arg_fault = KASAN_ARG_FAULT_PANIC_ON_WRITE;
64 else
65 return -EINVAL;
66
67 return 0;
68}
69early_param("kasan.fault", early_kasan_fault);
70
71static int __init kasan_set_multi_shot(char *str)
72{
73 set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
74 return 1;
75}
76__setup("kasan_multi_shot", kasan_set_multi_shot);
77
78/*
79 * This function is used to check whether KASAN reports are suppressed for
80 * software KASAN modes via kasan_disable/enable_current() critical sections.
81 *
82 * This is done to avoid:
83 * 1. False-positive reports when accessing slab metadata,
84 * 2. Deadlocking when poisoned memory is accessed by the reporting code.
85 *
86 * Hardware Tag-Based KASAN instead relies on:
87 * For #1: Resetting tags via kasan_reset_tag().
88 * For #2: Suppression of tag checks via CPU, see report_suppress_start/end().
89 */
90static bool report_suppressed_sw(void)
91{
92#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
93 if (current->kasan_depth)
94 return true;
95#endif
96 return false;
97}
98
99static void report_suppress_start(void)
100{
101#ifdef CONFIG_KASAN_HW_TAGS
102 /*
103 * Disable preemption for the duration of printing a KASAN report, as
104 * hw_suppress_tag_checks_start() disables checks on the current CPU.
105 */
106 preempt_disable();
107 hw_suppress_tag_checks_start();
108#else
109 kasan_disable_current();
110#endif
111}
112
113static void report_suppress_stop(void)
114{
115#ifdef CONFIG_KASAN_HW_TAGS
116 hw_suppress_tag_checks_stop();
117 preempt_enable();
118#else
119 kasan_enable_current();
120#endif
121}
122
123/*
124 * Used to avoid reporting more than one KASAN bug unless kasan_multi_shot
125 * is enabled. Note that KASAN tests effectively enable kasan_multi_shot
126 * for their duration.
127 */
128static bool report_enabled(void)
129{
130 if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
131 return true;
132 return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
133}
134
135#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST) || IS_ENABLED(CONFIG_KASAN_MODULE_TEST)
136
137bool kasan_save_enable_multi_shot(void)
138{
139 return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
140}
141EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
142
143void kasan_restore_multi_shot(bool enabled)
144{
145 if (!enabled)
146 clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
147}
148EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
149
150#endif
151
152#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
153
154/*
155 * Whether the KASAN KUnit test suite is currently being executed.
156 * Updated in kasan_test.c.
157 */
158static bool kasan_kunit_executing;
159
160void kasan_kunit_test_suite_start(void)
161{
162 WRITE_ONCE(kasan_kunit_executing, true);
163}
164EXPORT_SYMBOL_GPL(kasan_kunit_test_suite_start);
165
166void kasan_kunit_test_suite_end(void)
167{
168 WRITE_ONCE(kasan_kunit_executing, false);
169}
170EXPORT_SYMBOL_GPL(kasan_kunit_test_suite_end);
171
172static bool kasan_kunit_test_suite_executing(void)
173{
174 return READ_ONCE(kasan_kunit_executing);
175}
176
177#else /* CONFIG_KASAN_KUNIT_TEST */
178
179static inline bool kasan_kunit_test_suite_executing(void) { return false; }
180
181#endif /* CONFIG_KASAN_KUNIT_TEST */
182
183#if IS_ENABLED(CONFIG_KUNIT)
184
185static void fail_non_kasan_kunit_test(void)
186{
187 struct kunit *test;
188
189 if (kasan_kunit_test_suite_executing())
190 return;
191
192 test = current->kunit_test;
193 if (test)
194 kunit_set_failure(test);
195}
196
197#else /* CONFIG_KUNIT */
198
199static inline void fail_non_kasan_kunit_test(void) { }
200
201#endif /* CONFIG_KUNIT */
202
203static DEFINE_SPINLOCK(report_lock);
204
205static void start_report(unsigned long *flags, bool sync)
206{
207 fail_non_kasan_kunit_test();
208 /* Respect the /proc/sys/kernel/traceoff_on_warning interface. */
209 disable_trace_on_warning();
210 /* Do not allow LOCKDEP mangling KASAN reports. */
211 lockdep_off();
212 /* Make sure we don't end up in loop. */
213 report_suppress_start();
214 spin_lock_irqsave(&report_lock, *flags);
215 pr_err("==================================================================\n");
216}
217
218static void end_report(unsigned long *flags, const void *addr, bool is_write)
219{
220 if (addr)
221 trace_error_report_end(ERROR_DETECTOR_KASAN,
222 (unsigned long)addr);
223 pr_err("==================================================================\n");
224 spin_unlock_irqrestore(&report_lock, *flags);
225 if (!test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
226 check_panic_on_warn("KASAN");
227 switch (kasan_arg_fault) {
228 case KASAN_ARG_FAULT_DEFAULT:
229 case KASAN_ARG_FAULT_REPORT:
230 break;
231 case KASAN_ARG_FAULT_PANIC:
232 panic("kasan.fault=panic set ...\n");
233 break;
234 case KASAN_ARG_FAULT_PANIC_ON_WRITE:
235 if (is_write)
236 panic("kasan.fault=panic_on_write set ...\n");
237 break;
238 }
239 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
240 lockdep_on();
241 report_suppress_stop();
242}
243
244static void print_error_description(struct kasan_report_info *info)
245{
246 pr_err("BUG: KASAN: %s in %pS\n", info->bug_type, (void *)info->ip);
247
248 if (info->type != KASAN_REPORT_ACCESS) {
249 pr_err("Free of addr %px by task %s/%d\n",
250 info->access_addr, current->comm, task_pid_nr(current));
251 return;
252 }
253
254 if (info->access_size)
255 pr_err("%s of size %zu at addr %px by task %s/%d\n",
256 info->is_write ? "Write" : "Read", info->access_size,
257 info->access_addr, current->comm, task_pid_nr(current));
258 else
259 pr_err("%s at addr %px by task %s/%d\n",
260 info->is_write ? "Write" : "Read",
261 info->access_addr, current->comm, task_pid_nr(current));
262}
263
264static void print_track(struct kasan_track *track, const char *prefix)
265{
266#ifdef CONFIG_KASAN_EXTRA_INFO
267 u64 ts_nsec = track->timestamp;
268 unsigned long rem_usec;
269
270 ts_nsec <<= 3;
271 rem_usec = do_div(ts_nsec, NSEC_PER_SEC) / 1000;
272
273 pr_err("%s by task %u on cpu %d at %lu.%06lus:\n",
274 prefix, track->pid, track->cpu,
275 (unsigned long)ts_nsec, rem_usec);
276#else
277 pr_err("%s by task %u:\n", prefix, track->pid);
278#endif /* CONFIG_KASAN_EXTRA_INFO */
279 if (track->stack)
280 stack_depot_print(track->stack);
281 else
282 pr_err("(stack is not available)\n");
283}
284
285static inline struct page *addr_to_page(const void *addr)
286{
287 if (virt_addr_valid(addr))
288 return virt_to_head_page(addr);
289 return NULL;
290}
291
292static void describe_object_addr(const void *addr, struct kasan_report_info *info)
293{
294 unsigned long access_addr = (unsigned long)addr;
295 unsigned long object_addr = (unsigned long)info->object;
296 const char *rel_type, *region_state = "";
297 int rel_bytes;
298
299 pr_err("The buggy address belongs to the object at %px\n"
300 " which belongs to the cache %s of size %d\n",
301 info->object, info->cache->name, info->cache->object_size);
302
303 if (access_addr < object_addr) {
304 rel_type = "to the left";
305 rel_bytes = object_addr - access_addr;
306 } else if (access_addr >= object_addr + info->alloc_size) {
307 rel_type = "to the right";
308 rel_bytes = access_addr - (object_addr + info->alloc_size);
309 } else {
310 rel_type = "inside";
311 rel_bytes = access_addr - object_addr;
312 }
313
314 /*
315 * Tag-Based modes use the stack ring to infer the bug type, but the
316 * memory region state description is generated based on the metadata.
317 * Thus, defining the region state as below can contradict the metadata.
318 * Fixing this requires further improvements, so only infer the state
319 * for the Generic mode.
320 */
321 if (IS_ENABLED(CONFIG_KASAN_GENERIC)) {
322 if (strcmp(info->bug_type, "slab-out-of-bounds") == 0)
323 region_state = "allocated ";
324 else if (strcmp(info->bug_type, "slab-use-after-free") == 0)
325 region_state = "freed ";
326 }
327
328 pr_err("The buggy address is located %d bytes %s of\n"
329 " %s%zu-byte region [%px, %px)\n",
330 rel_bytes, rel_type, region_state, info->alloc_size,
331 (void *)object_addr, (void *)(object_addr + info->alloc_size));
332}
333
334static void describe_object_stacks(struct kasan_report_info *info)
335{
336 if (info->alloc_track.stack) {
337 print_track(&info->alloc_track, "Allocated");
338 pr_err("\n");
339 }
340
341 if (info->free_track.stack) {
342 print_track(&info->free_track, "Freed");
343 pr_err("\n");
344 }
345
346 kasan_print_aux_stacks(info->cache, info->object);
347}
348
349static void describe_object(const void *addr, struct kasan_report_info *info)
350{
351 if (kasan_stack_collection_enabled())
352 describe_object_stacks(info);
353 describe_object_addr(addr, info);
354}
355
356static inline bool kernel_or_module_addr(const void *addr)
357{
358 if (is_kernel((unsigned long)addr))
359 return true;
360 if (is_module_address((unsigned long)addr))
361 return true;
362 return false;
363}
364
365static inline bool init_task_stack_addr(const void *addr)
366{
367 return addr >= (void *)&init_thread_union.stack &&
368 (addr <= (void *)&init_thread_union.stack +
369 sizeof(init_thread_union.stack));
370}
371
372static void print_address_description(void *addr, u8 tag,
373 struct kasan_report_info *info)
374{
375 struct page *page = addr_to_page(addr);
376
377 dump_stack_lvl(KERN_ERR);
378 pr_err("\n");
379
380 if (info->cache && info->object) {
381 describe_object(addr, info);
382 pr_err("\n");
383 }
384
385 if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
386 pr_err("The buggy address belongs to the variable:\n");
387 pr_err(" %pS\n", addr);
388 pr_err("\n");
389 }
390
391 if (object_is_on_stack(addr)) {
392 /*
393 * Currently, KASAN supports printing frame information only
394 * for accesses to the task's own stack.
395 */
396 kasan_print_address_stack_frame(addr);
397 pr_err("\n");
398 }
399
400 if (is_vmalloc_addr(addr)) {
401 struct vm_struct *va = find_vm_area(addr);
402
403 if (va) {
404 pr_err("The buggy address belongs to the virtual mapping at\n"
405 " [%px, %px) created by:\n"
406 " %pS\n",
407 va->addr, va->addr + va->size, va->caller);
408 pr_err("\n");
409
410 page = vmalloc_to_page(addr);
411 }
412 }
413
414 if (page) {
415 pr_err("The buggy address belongs to the physical page:\n");
416 dump_page(page, "kasan: bad access detected");
417 pr_err("\n");
418 }
419}
420
421static bool meta_row_is_guilty(const void *row, const void *addr)
422{
423 return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW);
424}
425
426static int meta_pointer_offset(const void *row, const void *addr)
427{
428 /*
429 * Memory state around the buggy address:
430 * ff00ff00ff00ff00: 00 00 00 05 fe fe fe fe fe fe fe fe fe fe fe fe
431 * ...
432 *
433 * The length of ">ff00ff00ff00ff00: " is
434 * 3 + (BITS_PER_LONG / 8) * 2 chars.
435 * The length of each granule metadata is 2 bytes
436 * plus 1 byte for space.
437 */
438 return 3 + (BITS_PER_LONG / 8) * 2 +
439 (addr - row) / KASAN_GRANULE_SIZE * 3 + 1;
440}
441
442static void print_memory_metadata(const void *addr)
443{
444 int i;
445 void *row;
446
447 row = (void *)round_down((unsigned long)addr, META_MEM_BYTES_PER_ROW)
448 - META_ROWS_AROUND_ADDR * META_MEM_BYTES_PER_ROW;
449
450 pr_err("Memory state around the buggy address:\n");
451
452 for (i = -META_ROWS_AROUND_ADDR; i <= META_ROWS_AROUND_ADDR; i++) {
453 char buffer[4 + (BITS_PER_LONG / 8) * 2];
454 char metadata[META_BYTES_PER_ROW];
455
456 snprintf(buffer, sizeof(buffer),
457 (i == 0) ? ">%px: " : " %px: ", row);
458
459 /*
460 * We should not pass a shadow pointer to generic
461 * function, because generic functions may try to
462 * access kasan mapping for the passed address.
463 */
464 kasan_metadata_fetch_row(&metadata[0], row);
465
466 print_hex_dump(KERN_ERR, buffer,
467 DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1,
468 metadata, META_BYTES_PER_ROW, 0);
469
470 if (meta_row_is_guilty(row, addr))
471 pr_err("%*c\n", meta_pointer_offset(row, addr), '^');
472
473 row += META_MEM_BYTES_PER_ROW;
474 }
475}
476
477static void print_report(struct kasan_report_info *info)
478{
479 void *addr = kasan_reset_tag((void *)info->access_addr);
480 u8 tag = get_tag((void *)info->access_addr);
481
482 print_error_description(info);
483 if (addr_has_metadata(addr))
484 kasan_print_tags(tag, info->first_bad_addr);
485 pr_err("\n");
486
487 if (addr_has_metadata(addr)) {
488 print_address_description(addr, tag, info);
489 print_memory_metadata(info->first_bad_addr);
490 } else {
491 dump_stack_lvl(KERN_ERR);
492 }
493}
494
495static void complete_report_info(struct kasan_report_info *info)
496{
497 void *addr = kasan_reset_tag((void *)info->access_addr);
498 struct slab *slab;
499
500 if (info->type == KASAN_REPORT_ACCESS)
501 info->first_bad_addr = kasan_find_first_bad_addr(
502 (void *)info->access_addr, info->access_size);
503 else
504 info->first_bad_addr = addr;
505
506 slab = kasan_addr_to_slab(addr);
507 if (slab) {
508 info->cache = slab->slab_cache;
509 info->object = nearest_obj(info->cache, slab, addr);
510
511 /* Try to determine allocation size based on the metadata. */
512 info->alloc_size = kasan_get_alloc_size(info->object, info->cache);
513 /* Fallback to the object size if failed. */
514 if (!info->alloc_size)
515 info->alloc_size = info->cache->object_size;
516 } else
517 info->cache = info->object = NULL;
518
519 switch (info->type) {
520 case KASAN_REPORT_INVALID_FREE:
521 info->bug_type = "invalid-free";
522 break;
523 case KASAN_REPORT_DOUBLE_FREE:
524 info->bug_type = "double-free";
525 break;
526 default:
527 /* bug_type filled in by kasan_complete_mode_report_info. */
528 break;
529 }
530
531 /* Fill in mode-specific report info fields. */
532 kasan_complete_mode_report_info(info);
533}
534
535void kasan_report_invalid_free(void *ptr, unsigned long ip, enum kasan_report_type type)
536{
537 unsigned long flags;
538 struct kasan_report_info info;
539
540 /*
541 * Do not check report_suppressed_sw(), as an invalid-free cannot be
542 * caused by accessing poisoned memory and thus should not be suppressed
543 * by kasan_disable/enable_current() critical sections.
544 *
545 * Note that for Hardware Tag-Based KASAN, kasan_report_invalid_free()
546 * is triggered by explicit tag checks and not by the ones performed by
547 * the CPU. Thus, reporting invalid-free is not suppressed as well.
548 */
549 if (unlikely(!report_enabled()))
550 return;
551
552 start_report(&flags, true);
553
554 __memset(&info, 0, sizeof(info));
555 info.type = type;
556 info.access_addr = ptr;
557 info.access_size = 0;
558 info.is_write = false;
559 info.ip = ip;
560
561 complete_report_info(&info);
562
563 print_report(&info);
564
565 /*
566 * Invalid free is considered a "write" since the allocator's metadata
567 * updates involves writes.
568 */
569 end_report(&flags, ptr, true);
570}
571
572/*
573 * kasan_report() is the only reporting function that uses
574 * user_access_save/restore(): kasan_report_invalid_free() cannot be called
575 * from a UACCESS region, and kasan_report_async() is not used on x86.
576 */
577bool kasan_report(const void *addr, size_t size, bool is_write,
578 unsigned long ip)
579{
580 bool ret = true;
581 unsigned long ua_flags = user_access_save();
582 unsigned long irq_flags;
583 struct kasan_report_info info;
584
585 if (unlikely(report_suppressed_sw()) || unlikely(!report_enabled())) {
586 ret = false;
587 goto out;
588 }
589
590 start_report(&irq_flags, true);
591
592 __memset(&info, 0, sizeof(info));
593 info.type = KASAN_REPORT_ACCESS;
594 info.access_addr = addr;
595 info.access_size = size;
596 info.is_write = is_write;
597 info.ip = ip;
598
599 complete_report_info(&info);
600
601 print_report(&info);
602
603 end_report(&irq_flags, (void *)addr, is_write);
604
605out:
606 user_access_restore(ua_flags);
607
608 return ret;
609}
610
611#ifdef CONFIG_KASAN_HW_TAGS
612void kasan_report_async(void)
613{
614 unsigned long flags;
615
616 /*
617 * Do not check report_suppressed_sw(), as
618 * kasan_disable/enable_current() critical sections do not affect
619 * Hardware Tag-Based KASAN.
620 */
621 if (unlikely(!report_enabled()))
622 return;
623
624 start_report(&flags, false);
625 pr_err("BUG: KASAN: invalid-access\n");
626 pr_err("Asynchronous fault: no details available\n");
627 pr_err("\n");
628 dump_stack_lvl(KERN_ERR);
629 /*
630 * Conservatively set is_write=true, because no details are available.
631 * In this mode, kasan.fault=panic_on_write is like kasan.fault=panic.
632 */
633 end_report(&flags, NULL, true);
634}
635#endif /* CONFIG_KASAN_HW_TAGS */
636
637#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
638/*
639 * With compiler-based KASAN modes, accesses to bogus pointers (outside of the
640 * mapped kernel address space regions) cause faults when KASAN tries to check
641 * the shadow memory before the actual memory access. This results in cryptic
642 * GPF reports, which are hard for users to interpret. This hook helps users to
643 * figure out what the original bogus pointer was.
644 */
645void kasan_non_canonical_hook(unsigned long addr)
646{
647 unsigned long orig_addr;
648 const char *bug_type;
649
650 /*
651 * All addresses that came as a result of the memory-to-shadow mapping
652 * (even for bogus pointers) must be >= KASAN_SHADOW_OFFSET.
653 */
654 if (addr < KASAN_SHADOW_OFFSET)
655 return;
656
657 orig_addr = (unsigned long)kasan_shadow_to_mem((void *)addr);
658
659 /*
660 * For faults near the shadow address for NULL, we can be fairly certain
661 * that this is a KASAN shadow memory access.
662 * For faults that correspond to the shadow for low or high canonical
663 * addresses, we can still be pretty sure: these shadow regions are a
664 * fairly narrow chunk of the address space.
665 * But the shadow for non-canonical addresses is a really large chunk
666 * of the address space. For this case, we still print the decoded
667 * address, but make it clear that this is not necessarily what's
668 * actually going on.
669 */
670 if (orig_addr < PAGE_SIZE)
671 bug_type = "null-ptr-deref";
672 else if (orig_addr < TASK_SIZE)
673 bug_type = "probably user-memory-access";
674 else if (addr_in_shadow((void *)addr))
675 bug_type = "probably wild-memory-access";
676 else
677 bug_type = "maybe wild-memory-access";
678 pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
679 orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1);
680}
681#endif
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/ftrace.h>
17#include <linux/kernel.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
29#include <asm/sections.h>
30
31#include "kasan.h"
32#include "../slab.h"
33
34/* Shadow layout customization. */
35#define SHADOW_BYTES_PER_BLOCK 1
36#define SHADOW_BLOCKS_PER_ROW 16
37#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
38#define SHADOW_ROWS_AROUND_ADDR 2
39
40static const void *find_first_bad_addr(const void *addr, size_t size)
41{
42 u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
43 const void *first_bad_addr = addr;
44
45 while (!shadow_val && first_bad_addr < addr + size) {
46 first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
47 shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
48 }
49 return first_bad_addr;
50}
51
52static void print_error_description(struct kasan_access_info *info)
53{
54 const char *bug_type = "unknown-crash";
55 u8 *shadow_addr;
56
57 info->first_bad_addr = find_first_bad_addr(info->access_addr,
58 info->access_size);
59
60 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
61
62 /*
63 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
64 * at the next shadow byte to determine the type of the bad access.
65 */
66 if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
67 shadow_addr++;
68
69 switch (*shadow_addr) {
70 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
71 /*
72 * In theory it's still possible to see these shadow values
73 * due to a data race in the kernel code.
74 */
75 bug_type = "out-of-bounds";
76 break;
77 case KASAN_PAGE_REDZONE:
78 case KASAN_KMALLOC_REDZONE:
79 bug_type = "slab-out-of-bounds";
80 break;
81 case KASAN_GLOBAL_REDZONE:
82 bug_type = "global-out-of-bounds";
83 break;
84 case KASAN_STACK_LEFT:
85 case KASAN_STACK_MID:
86 case KASAN_STACK_RIGHT:
87 case KASAN_STACK_PARTIAL:
88 bug_type = "stack-out-of-bounds";
89 break;
90 case KASAN_FREE_PAGE:
91 case KASAN_KMALLOC_FREE:
92 bug_type = "use-after-free";
93 break;
94 case KASAN_USE_AFTER_SCOPE:
95 bug_type = "use-after-scope";
96 break;
97 }
98
99 pr_err("BUG: KASAN: %s in %pS at addr %p\n",
100 bug_type, (void *)info->ip,
101 info->access_addr);
102 pr_err("%s of size %zu by task %s/%d\n",
103 info->is_write ? "Write" : "Read",
104 info->access_size, current->comm, task_pid_nr(current));
105}
106
107static inline bool kernel_or_module_addr(const void *addr)
108{
109 if (addr >= (void *)_stext && addr < (void *)_end)
110 return true;
111 if (is_module_address((unsigned long)addr))
112 return true;
113 return false;
114}
115
116static inline bool init_task_stack_addr(const void *addr)
117{
118 return addr >= (void *)&init_thread_union.stack &&
119 (addr <= (void *)&init_thread_union.stack +
120 sizeof(init_thread_union.stack));
121}
122
123static DEFINE_SPINLOCK(report_lock);
124
125static void kasan_start_report(unsigned long *flags)
126{
127 /*
128 * Make sure we don't end up in loop.
129 */
130 kasan_disable_current();
131 spin_lock_irqsave(&report_lock, *flags);
132 pr_err("==================================================================\n");
133}
134
135static void kasan_end_report(unsigned long *flags)
136{
137 pr_err("==================================================================\n");
138 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
139 spin_unlock_irqrestore(&report_lock, *flags);
140 if (panic_on_warn)
141 panic("panic_on_warn set ...\n");
142 kasan_enable_current();
143}
144
145static void print_track(struct kasan_track *track)
146{
147 pr_err("PID = %u\n", track->pid);
148 if (track->stack) {
149 struct stack_trace trace;
150
151 depot_fetch_stack(track->stack, &trace);
152 print_stack_trace(&trace, 0);
153 } else {
154 pr_err("(stack is not available)\n");
155 }
156}
157
158static void kasan_object_err(struct kmem_cache *cache, void *object)
159{
160 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
161
162 dump_stack();
163 pr_err("Object at %p, in cache %s size: %d\n", object, cache->name,
164 cache->object_size);
165
166 if (!(cache->flags & SLAB_KASAN))
167 return;
168
169 pr_err("Allocated:\n");
170 print_track(&alloc_info->alloc_track);
171 pr_err("Freed:\n");
172 print_track(&alloc_info->free_track);
173}
174
175void kasan_report_double_free(struct kmem_cache *cache, void *object,
176 s8 shadow)
177{
178 unsigned long flags;
179
180 kasan_start_report(&flags);
181 pr_err("BUG: Double free or freeing an invalid pointer\n");
182 pr_err("Unexpected shadow byte: 0x%hhX\n", shadow);
183 kasan_object_err(cache, object);
184 kasan_end_report(&flags);
185}
186
187static void print_address_description(struct kasan_access_info *info)
188{
189 const void *addr = info->access_addr;
190
191 if ((addr >= (void *)PAGE_OFFSET) &&
192 (addr < high_memory)) {
193 struct page *page = virt_to_head_page(addr);
194
195 if (PageSlab(page)) {
196 void *object;
197 struct kmem_cache *cache = page->slab_cache;
198 object = nearest_obj(cache, page,
199 (void *)info->access_addr);
200 kasan_object_err(cache, object);
201 return;
202 }
203 dump_page(page, "kasan: bad access detected");
204 }
205
206 if (kernel_or_module_addr(addr)) {
207 if (!init_task_stack_addr(addr))
208 pr_err("Address belongs to variable %pS\n", addr);
209 }
210 dump_stack();
211}
212
213static bool row_is_guilty(const void *row, const void *guilty)
214{
215 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
216}
217
218static int shadow_pointer_offset(const void *row, const void *shadow)
219{
220 /* The length of ">ff00ff00ff00ff00: " is
221 * 3 + (BITS_PER_LONG/8)*2 chars.
222 */
223 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
224 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
225}
226
227static void print_shadow_for_address(const void *addr)
228{
229 int i;
230 const void *shadow = kasan_mem_to_shadow(addr);
231 const void *shadow_row;
232
233 shadow_row = (void *)round_down((unsigned long)shadow,
234 SHADOW_BYTES_PER_ROW)
235 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
236
237 pr_err("Memory state around the buggy address:\n");
238
239 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
240 const void *kaddr = kasan_shadow_to_mem(shadow_row);
241 char buffer[4 + (BITS_PER_LONG/8)*2];
242 char shadow_buf[SHADOW_BYTES_PER_ROW];
243
244 snprintf(buffer, sizeof(buffer),
245 (i == 0) ? ">%p: " : " %p: ", kaddr);
246 /*
247 * We should not pass a shadow pointer to generic
248 * function, because generic functions may try to
249 * access kasan mapping for the passed address.
250 */
251 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
252 print_hex_dump(KERN_ERR, buffer,
253 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
254 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
255
256 if (row_is_guilty(shadow_row, shadow))
257 pr_err("%*c\n",
258 shadow_pointer_offset(shadow_row, shadow),
259 '^');
260
261 shadow_row += SHADOW_BYTES_PER_ROW;
262 }
263}
264
265static void kasan_report_error(struct kasan_access_info *info)
266{
267 unsigned long flags;
268 const char *bug_type;
269
270 kasan_start_report(&flags);
271
272 if (info->access_addr <
273 kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
274 if ((unsigned long)info->access_addr < PAGE_SIZE)
275 bug_type = "null-ptr-deref";
276 else if ((unsigned long)info->access_addr < TASK_SIZE)
277 bug_type = "user-memory-access";
278 else
279 bug_type = "wild-memory-access";
280 pr_err("BUG: KASAN: %s on address %p\n",
281 bug_type, info->access_addr);
282 pr_err("%s of size %zu by task %s/%d\n",
283 info->is_write ? "Write" : "Read",
284 info->access_size, current->comm,
285 task_pid_nr(current));
286 dump_stack();
287 } else {
288 print_error_description(info);
289 print_address_description(info);
290 print_shadow_for_address(info->first_bad_addr);
291 }
292
293 kasan_end_report(&flags);
294}
295
296void kasan_report(unsigned long addr, size_t size,
297 bool is_write, unsigned long ip)
298{
299 struct kasan_access_info info;
300
301 if (likely(!kasan_report_enabled()))
302 return;
303
304 disable_trace_on_warning();
305
306 info.access_addr = (void *)addr;
307 info.access_size = size;
308 info.is_write = is_write;
309 info.ip = ip;
310
311 kasan_report_error(&info);
312}
313
314
315#define DEFINE_ASAN_REPORT_LOAD(size) \
316void __asan_report_load##size##_noabort(unsigned long addr) \
317{ \
318 kasan_report(addr, size, false, _RET_IP_); \
319} \
320EXPORT_SYMBOL(__asan_report_load##size##_noabort)
321
322#define DEFINE_ASAN_REPORT_STORE(size) \
323void __asan_report_store##size##_noabort(unsigned long addr) \
324{ \
325 kasan_report(addr, size, true, _RET_IP_); \
326} \
327EXPORT_SYMBOL(__asan_report_store##size##_noabort)
328
329DEFINE_ASAN_REPORT_LOAD(1);
330DEFINE_ASAN_REPORT_LOAD(2);
331DEFINE_ASAN_REPORT_LOAD(4);
332DEFINE_ASAN_REPORT_LOAD(8);
333DEFINE_ASAN_REPORT_LOAD(16);
334DEFINE_ASAN_REPORT_STORE(1);
335DEFINE_ASAN_REPORT_STORE(2);
336DEFINE_ASAN_REPORT_STORE(4);
337DEFINE_ASAN_REPORT_STORE(8);
338DEFINE_ASAN_REPORT_STORE(16);
339
340void __asan_report_load_n_noabort(unsigned long addr, size_t size)
341{
342 kasan_report(addr, size, false, _RET_IP_);
343}
344EXPORT_SYMBOL(__asan_report_load_n_noabort);
345
346void __asan_report_store_n_noabort(unsigned long addr, size_t size)
347{
348 kasan_report(addr, size, true, _RET_IP_);
349}
350EXPORT_SYMBOL(__asan_report_store_n_noabort);