Merge tag 'regmap-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie...
[linux-2.6-microblaze.git] / mm / kasan / report.c
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 <linux/bitops.h>
13 #include <linux/ftrace.h>
14 #include <linux/init.h>
15 #include <linux/kernel.h>
16 #include <linux/mm.h>
17 #include <linux/printk.h>
18 #include <linux/sched.h>
19 #include <linux/slab.h>
20 #include <linux/stackdepot.h>
21 #include <linux/stacktrace.h>
22 #include <linux/string.h>
23 #include <linux/types.h>
24 #include <linux/kasan.h>
25 #include <linux/module.h>
26 #include <linux/sched/task_stack.h>
27 #include <linux/uaccess.h>
28 #include <trace/events/error_report.h>
29
30 #include <asm/sections.h>
31
32 #include <kunit/test.h>
33
34 #include "kasan.h"
35 #include "../slab.h"
36
37 static unsigned long kasan_flags;
38
39 #define KASAN_BIT_REPORTED      0
40 #define KASAN_BIT_MULTI_SHOT    1
41
42 enum kasan_arg_fault {
43         KASAN_ARG_FAULT_DEFAULT,
44         KASAN_ARG_FAULT_REPORT,
45         KASAN_ARG_FAULT_PANIC,
46 };
47
48 static enum kasan_arg_fault kasan_arg_fault __ro_after_init = KASAN_ARG_FAULT_DEFAULT;
49
50 /* kasan.fault=report/panic */
51 static 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 }
65 early_param("kasan.fault", early_kasan_fault);
66
67 bool kasan_save_enable_multi_shot(void)
68 {
69         return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
70 }
71 EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
72
73 void kasan_restore_multi_shot(bool enabled)
74 {
75         if (!enabled)
76                 clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
77 }
78 EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
79
80 static int __init kasan_set_multi_shot(char *str)
81 {
82         set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
83         return 1;
84 }
85 __setup("kasan_multi_shot", kasan_set_multi_shot);
86
87 static void print_error_description(struct kasan_access_info *info)
88 {
89         pr_err("BUG: KASAN: %s in %pS\n",
90                 kasan_get_bug_type(info), (void *)info->ip);
91         if (info->access_size)
92                 pr_err("%s of size %zu at addr %px by task %s/%d\n",
93                         info->is_write ? "Write" : "Read", info->access_size,
94                         info->access_addr, current->comm, task_pid_nr(current));
95         else
96                 pr_err("%s at addr %px by task %s/%d\n",
97                         info->is_write ? "Write" : "Read",
98                         info->access_addr, current->comm, task_pid_nr(current));
99 }
100
101 static DEFINE_SPINLOCK(report_lock);
102
103 static void start_report(unsigned long *flags)
104 {
105         /*
106          * Make sure we don't end up in loop.
107          */
108         kasan_disable_current();
109         spin_lock_irqsave(&report_lock, *flags);
110         pr_err("==================================================================\n");
111 }
112
113 static void end_report(unsigned long *flags, unsigned long addr)
114 {
115         if (!kasan_async_fault_possible())
116                 trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
117         pr_err("==================================================================\n");
118         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
119         spin_unlock_irqrestore(&report_lock, *flags);
120         if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) {
121                 /*
122                  * This thread may hit another WARN() in the panic path.
123                  * Resetting this prevents additional WARN() from panicking the
124                  * system on this thread.  Other threads are blocked by the
125                  * panic_mutex in panic().
126                  */
127                 panic_on_warn = 0;
128                 panic("panic_on_warn set ...\n");
129         }
130         if (kasan_arg_fault == KASAN_ARG_FAULT_PANIC)
131                 panic("kasan.fault=panic set ...\n");
132         kasan_enable_current();
133 }
134
135 static void print_track(struct kasan_track *track, const char *prefix)
136 {
137         pr_err("%s by task %u:\n", prefix, track->pid);
138         if (track->stack) {
139                 stack_depot_print(track->stack);
140         } else {
141                 pr_err("(stack is not available)\n");
142         }
143 }
144
145 struct page *kasan_addr_to_page(const void *addr)
146 {
147         if ((addr >= (void *)PAGE_OFFSET) &&
148                         (addr < high_memory))
149                 return virt_to_head_page(addr);
150         return NULL;
151 }
152
153 struct slab *kasan_addr_to_slab(const void *addr)
154 {
155         if ((addr >= (void *)PAGE_OFFSET) &&
156                         (addr < high_memory))
157                 return virt_to_slab(addr);
158         return NULL;
159 }
160
161 static void describe_object_addr(struct kmem_cache *cache, void *object,
162                                 const void *addr)
163 {
164         unsigned long access_addr = (unsigned long)addr;
165         unsigned long object_addr = (unsigned long)object;
166         const char *rel_type;
167         int rel_bytes;
168
169         pr_err("The buggy address belongs to the object at %px\n"
170                " which belongs to the cache %s of size %d\n",
171                 object, cache->name, cache->object_size);
172
173         if (!addr)
174                 return;
175
176         if (access_addr < object_addr) {
177                 rel_type = "to the left";
178                 rel_bytes = object_addr - access_addr;
179         } else if (access_addr >= object_addr + cache->object_size) {
180                 rel_type = "to the right";
181                 rel_bytes = access_addr - (object_addr + cache->object_size);
182         } else {
183                 rel_type = "inside";
184                 rel_bytes = access_addr - object_addr;
185         }
186
187         pr_err("The buggy address is located %d bytes %s of\n"
188                " %d-byte region [%px, %px)\n",
189                 rel_bytes, rel_type, cache->object_size, (void *)object_addr,
190                 (void *)(object_addr + cache->object_size));
191 }
192
193 static void describe_object_stacks(struct kmem_cache *cache, void *object,
194                                         const void *addr, u8 tag)
195 {
196         struct kasan_alloc_meta *alloc_meta;
197         struct kasan_track *free_track;
198
199         alloc_meta = kasan_get_alloc_meta(cache, object);
200         if (alloc_meta) {
201                 print_track(&alloc_meta->alloc_track, "Allocated");
202                 pr_err("\n");
203         }
204
205         free_track = kasan_get_free_track(cache, object, tag);
206         if (free_track) {
207                 print_track(free_track, "Freed");
208                 pr_err("\n");
209         }
210
211 #ifdef CONFIG_KASAN_GENERIC
212         if (!alloc_meta)
213                 return;
214         if (alloc_meta->aux_stack[0]) {
215                 pr_err("Last potentially related work creation:\n");
216                 stack_depot_print(alloc_meta->aux_stack[0]);
217                 pr_err("\n");
218         }
219         if (alloc_meta->aux_stack[1]) {
220                 pr_err("Second to last potentially related work creation:\n");
221                 stack_depot_print(alloc_meta->aux_stack[1]);
222                 pr_err("\n");
223         }
224 #endif
225 }
226
227 static void describe_object(struct kmem_cache *cache, void *object,
228                                 const void *addr, u8 tag)
229 {
230         if (kasan_stack_collection_enabled())
231                 describe_object_stacks(cache, object, addr, tag);
232         describe_object_addr(cache, object, addr);
233 }
234
235 static inline bool kernel_or_module_addr(const void *addr)
236 {
237         if (is_kernel((unsigned long)addr))
238                 return true;
239         if (is_module_address((unsigned long)addr))
240                 return true;
241         return false;
242 }
243
244 static inline bool init_task_stack_addr(const void *addr)
245 {
246         return addr >= (void *)&init_thread_union.stack &&
247                 (addr <= (void *)&init_thread_union.stack +
248                         sizeof(init_thread_union.stack));
249 }
250
251 static void print_address_description(void *addr, u8 tag)
252 {
253         struct page *page = kasan_addr_to_page(addr);
254
255         dump_stack_lvl(KERN_ERR);
256         pr_err("\n");
257
258         if (page && PageSlab(page)) {
259                 struct slab *slab = page_slab(page);
260                 struct kmem_cache *cache = slab->slab_cache;
261                 void *object = nearest_obj(cache, slab, addr);
262
263                 describe_object(cache, object, addr, tag);
264         }
265
266         if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
267                 pr_err("The buggy address belongs to the variable:\n");
268                 pr_err(" %pS\n", addr);
269         }
270
271         if (page) {
272                 pr_err("The buggy address belongs to the page:\n");
273                 dump_page(page, "kasan: bad access detected");
274         }
275
276         kasan_print_address_stack_frame(addr);
277 }
278
279 static bool meta_row_is_guilty(const void *row, const void *addr)
280 {
281         return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW);
282 }
283
284 static int meta_pointer_offset(const void *row, const void *addr)
285 {
286         /*
287          * Memory state around the buggy address:
288          *  ff00ff00ff00ff00: 00 00 00 05 fe fe fe fe fe fe fe fe fe fe fe fe
289          *  ...
290          *
291          * The length of ">ff00ff00ff00ff00: " is
292          *    3 + (BITS_PER_LONG / 8) * 2 chars.
293          * The length of each granule metadata is 2 bytes
294          *    plus 1 byte for space.
295          */
296         return 3 + (BITS_PER_LONG / 8) * 2 +
297                 (addr - row) / KASAN_GRANULE_SIZE * 3 + 1;
298 }
299
300 static void print_memory_metadata(const void *addr)
301 {
302         int i;
303         void *row;
304
305         row = (void *)round_down((unsigned long)addr, META_MEM_BYTES_PER_ROW)
306                         - META_ROWS_AROUND_ADDR * META_MEM_BYTES_PER_ROW;
307
308         pr_err("Memory state around the buggy address:\n");
309
310         for (i = -META_ROWS_AROUND_ADDR; i <= META_ROWS_AROUND_ADDR; i++) {
311                 char buffer[4 + (BITS_PER_LONG / 8) * 2];
312                 char metadata[META_BYTES_PER_ROW];
313
314                 snprintf(buffer, sizeof(buffer),
315                                 (i == 0) ? ">%px: " : " %px: ", row);
316
317                 /*
318                  * We should not pass a shadow pointer to generic
319                  * function, because generic functions may try to
320                  * access kasan mapping for the passed address.
321                  */
322                 kasan_metadata_fetch_row(&metadata[0], row);
323
324                 print_hex_dump(KERN_ERR, buffer,
325                         DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1,
326                         metadata, META_BYTES_PER_ROW, 0);
327
328                 if (meta_row_is_guilty(row, addr))
329                         pr_err("%*c\n", meta_pointer_offset(row, addr), '^');
330
331                 row += META_MEM_BYTES_PER_ROW;
332         }
333 }
334
335 static bool report_enabled(void)
336 {
337 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
338         if (current->kasan_depth)
339                 return false;
340 #endif
341         if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
342                 return true;
343         return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
344 }
345
346 #if IS_ENABLED(CONFIG_KUNIT)
347 static void kasan_update_kunit_status(struct kunit *cur_test)
348 {
349         struct kunit_resource *resource;
350         struct kunit_kasan_expectation *kasan_data;
351
352         resource = kunit_find_named_resource(cur_test, "kasan_data");
353
354         if (!resource) {
355                 kunit_set_failure(cur_test);
356                 return;
357         }
358
359         kasan_data = (struct kunit_kasan_expectation *)resource->data;
360         WRITE_ONCE(kasan_data->report_found, true);
361         kunit_put_resource(resource);
362 }
363 #endif /* IS_ENABLED(CONFIG_KUNIT) */
364
365 void kasan_report_invalid_free(void *object, unsigned long ip)
366 {
367         unsigned long flags;
368         u8 tag = get_tag(object);
369
370         object = kasan_reset_tag(object);
371
372 #if IS_ENABLED(CONFIG_KUNIT)
373         if (current->kunit_test)
374                 kasan_update_kunit_status(current->kunit_test);
375 #endif /* IS_ENABLED(CONFIG_KUNIT) */
376
377         start_report(&flags);
378         pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
379         kasan_print_tags(tag, object);
380         pr_err("\n");
381         print_address_description(object, tag);
382         pr_err("\n");
383         print_memory_metadata(object);
384         end_report(&flags, (unsigned long)object);
385 }
386
387 #ifdef CONFIG_KASAN_HW_TAGS
388 void kasan_report_async(void)
389 {
390         unsigned long flags;
391
392 #if IS_ENABLED(CONFIG_KUNIT)
393         if (current->kunit_test)
394                 kasan_update_kunit_status(current->kunit_test);
395 #endif /* IS_ENABLED(CONFIG_KUNIT) */
396
397         start_report(&flags);
398         pr_err("BUG: KASAN: invalid-access\n");
399         pr_err("Asynchronous mode enabled: no access details available\n");
400         pr_err("\n");
401         dump_stack_lvl(KERN_ERR);
402         end_report(&flags, 0);
403 }
404 #endif /* CONFIG_KASAN_HW_TAGS */
405
406 static void __kasan_report(unsigned long addr, size_t size, bool is_write,
407                                 unsigned long ip)
408 {
409         struct kasan_access_info info;
410         void *tagged_addr;
411         void *untagged_addr;
412         unsigned long flags;
413
414 #if IS_ENABLED(CONFIG_KUNIT)
415         if (current->kunit_test)
416                 kasan_update_kunit_status(current->kunit_test);
417 #endif /* IS_ENABLED(CONFIG_KUNIT) */
418
419         disable_trace_on_warning();
420
421         tagged_addr = (void *)addr;
422         untagged_addr = kasan_reset_tag(tagged_addr);
423
424         info.access_addr = tagged_addr;
425         if (addr_has_metadata(untagged_addr))
426                 info.first_bad_addr =
427                         kasan_find_first_bad_addr(tagged_addr, size);
428         else
429                 info.first_bad_addr = untagged_addr;
430         info.access_size = size;
431         info.is_write = is_write;
432         info.ip = ip;
433
434         start_report(&flags);
435
436         print_error_description(&info);
437         if (addr_has_metadata(untagged_addr))
438                 kasan_print_tags(get_tag(tagged_addr), info.first_bad_addr);
439         pr_err("\n");
440
441         if (addr_has_metadata(untagged_addr)) {
442                 print_address_description(untagged_addr, get_tag(tagged_addr));
443                 pr_err("\n");
444                 print_memory_metadata(info.first_bad_addr);
445         } else {
446                 dump_stack_lvl(KERN_ERR);
447         }
448
449         end_report(&flags, addr);
450 }
451
452 bool kasan_report(unsigned long addr, size_t size, bool is_write,
453                         unsigned long ip)
454 {
455         unsigned long flags = user_access_save();
456         bool ret = false;
457
458         if (likely(report_enabled())) {
459                 __kasan_report(addr, size, is_write, ip);
460                 ret = true;
461         }
462
463         user_access_restore(flags);
464
465         return ret;
466 }
467
468 #ifdef CONFIG_KASAN_INLINE
469 /*
470  * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
471  * canonical half of the address space) cause out-of-bounds shadow memory reads
472  * before the actual access. For addresses in the low canonical half of the
473  * address space, as well as most non-canonical addresses, that out-of-bounds
474  * shadow memory access lands in the non-canonical part of the address space.
475  * Help the user figure out what the original bogus pointer was.
476  */
477 void kasan_non_canonical_hook(unsigned long addr)
478 {
479         unsigned long orig_addr;
480         const char *bug_type;
481
482         if (addr < KASAN_SHADOW_OFFSET)
483                 return;
484
485         orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT;
486         /*
487          * For faults near the shadow address for NULL, we can be fairly certain
488          * that this is a KASAN shadow memory access.
489          * For faults that correspond to shadow for low canonical addresses, we
490          * can still be pretty sure - that shadow region is a fairly narrow
491          * chunk of the non-canonical address space.
492          * But faults that look like shadow for non-canonical addresses are a
493          * really large chunk of the address space. In that case, we still
494          * print the decoded address, but make it clear that this is not
495          * necessarily what's actually going on.
496          */
497         if (orig_addr < PAGE_SIZE)
498                 bug_type = "null-ptr-deref";
499         else if (orig_addr < TASK_SIZE)
500                 bug_type = "probably user-memory-access";
501         else
502                 bug_type = "maybe wild-memory-access";
503         pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
504                  orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1);
505 }
506 #endif