blob: 8efc69473a37ad67675316e61888de73e006ab08 [file] [log] [blame]
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -08001/*
2 * This file contains error reporting code.
3 *
4 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
Andrey Ryabinin2baf9e82015-08-14 15:35:13 -07005 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -08006 *
Andrey Konovalov5d0926e2015-11-05 18:51:12 -08007 * Some code borrowed from https://github.com/xairy/kasan-prototype by
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -08008 * 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
Mark Rutlandb0845ce2017-03-31 15:12:04 -070016#include <linux/bitops.h>
Peter Zijlstra4f40c6e2017-02-03 13:13:12 -080017#include <linux/ftrace.h>
Mark Rutlandb0845ce2017-03-31 15:12:04 -070018#include <linux/init.h>
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080019#include <linux/kernel.h>
20#include <linux/mm.h>
21#include <linux/printk.h>
22#include <linux/sched.h>
23#include <linux/slab.h>
Alexander Potapenkocd110162016-03-25 14:22:08 -070024#include <linux/stackdepot.h>
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080025#include <linux/stacktrace.h>
26#include <linux/string.h>
27#include <linux/types.h>
28#include <linux/kasan.h>
Aneesh Kumar K.V527f2152015-11-05 18:50:46 -080029#include <linux/module.h>
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080030
Andrey Ryabininbebf56a2015-02-13 14:40:17 -080031#include <asm/sections.h>
32
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080033#include "kasan.h"
Andrey Ryabinin0316bec2015-02-13 14:39:42 -080034#include "../slab.h"
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080035
36/* Shadow layout customization. */
37#define SHADOW_BYTES_PER_BLOCK 1
38#define SHADOW_BLOCKS_PER_ROW 16
39#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
40#define SHADOW_ROWS_AROUND_ADDR 2
41
42static const void *find_first_bad_addr(const void *addr, size_t size)
43{
44 u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
45 const void *first_bad_addr = addr;
46
47 while (!shadow_val && first_bad_addr < addr + size) {
48 first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
49 shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
50 }
51 return first_bad_addr;
52}
53
Andrey Konovalov5e82cd12017-05-03 14:56:25 -070054static bool addr_has_shadow(struct kasan_access_info *info)
55{
56 return (info->access_addr >=
57 kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
58}
59
60static const char *get_shadow_bug_type(struct kasan_access_info *info)
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080061{
Andrey Konovalov0952d872015-11-05 18:50:58 -080062 const char *bug_type = "unknown-crash";
Andrey Konovalovcdf6a272015-11-05 18:51:01 -080063 u8 *shadow_addr;
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080064
65 info->first_bad_addr = find_first_bad_addr(info->access_addr,
66 info->access_size);
67
Andrey Konovalovcdf6a272015-11-05 18:51:01 -080068 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080069
Andrey Konovalovcdf6a272015-11-05 18:51:01 -080070 /*
71 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
72 * at the next shadow byte to determine the type of the bad access.
73 */
74 if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
75 shadow_addr++;
76
77 switch (*shadow_addr) {
Andrey Konovalov0952d872015-11-05 18:50:58 -080078 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
Andrey Konovalovcdf6a272015-11-05 18:51:01 -080079 /*
80 * In theory it's still possible to see these shadow values
81 * due to a data race in the kernel code.
82 */
Andrey Konovalov0952d872015-11-05 18:50:58 -080083 bug_type = "out-of-bounds";
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -080084 break;
Andrey Ryabinin0316bec2015-02-13 14:39:42 -080085 case KASAN_PAGE_REDZONE:
86 case KASAN_KMALLOC_REDZONE:
Andrey Konovalov0952d872015-11-05 18:50:58 -080087 bug_type = "slab-out-of-bounds";
88 break;
Andrey Ryabininbebf56a2015-02-13 14:40:17 -080089 case KASAN_GLOBAL_REDZONE:
Andrey Konovalov0952d872015-11-05 18:50:58 -080090 bug_type = "global-out-of-bounds";
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -080091 break;
Andrey Ryabininc420f162015-02-13 14:39:59 -080092 case KASAN_STACK_LEFT:
93 case KASAN_STACK_MID:
94 case KASAN_STACK_RIGHT:
95 case KASAN_STACK_PARTIAL:
Andrey Konovalov0952d872015-11-05 18:50:58 -080096 bug_type = "stack-out-of-bounds";
97 break;
98 case KASAN_FREE_PAGE:
99 case KASAN_KMALLOC_FREE:
100 bug_type = "use-after-free";
Andrey Ryabininc420f162015-02-13 14:39:59 -0800101 break;
Dmitry Vyukov828347f2016-11-30 15:54:16 -0800102 case KASAN_USE_AFTER_SCOPE:
103 bug_type = "use-after-scope";
104 break;
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800105 }
106
Andrey Konovalov5e82cd12017-05-03 14:56:25 -0700107 return bug_type;
108}
109
110const char *get_wild_bug_type(struct kasan_access_info *info)
111{
112 const char *bug_type = "unknown-crash";
113
114 if ((unsigned long)info->access_addr < PAGE_SIZE)
115 bug_type = "null-ptr-deref";
116 else if ((unsigned long)info->access_addr < TASK_SIZE)
117 bug_type = "user-memory-access";
118 else
119 bug_type = "wild-memory-access";
120
121 return bug_type;
122}
123
Andrey Konovalov7d418f72017-05-03 14:56:28 -0700124static const char *get_bug_type(struct kasan_access_info *info)
125{
126 if (addr_has_shadow(info))
127 return get_shadow_bug_type(info);
128 return get_wild_bug_type(info);
129}
130
Andrey Konovalov5e82cd12017-05-03 14:56:25 -0700131static void print_error_description(struct kasan_access_info *info)
132{
Andrey Konovalov7d418f72017-05-03 14:56:28 -0700133 const char *bug_type = get_bug_type(info);
Andrey Konovalov5e82cd12017-05-03 14:56:25 -0700134
Andrey Konovalov7f0a84c2017-05-03 14:56:38 -0700135 pr_err("BUG: KASAN: %s in %pS\n",
136 bug_type, (void *)info->ip);
137 pr_err("%s of size %zu at addr %p by task %s/%d\n",
Andrey Konovalov7d418f72017-05-03 14:56:28 -0700138 info->is_write ? "Write" : "Read", info->access_size,
Andrey Konovalov7f0a84c2017-05-03 14:56:38 -0700139 info->access_addr, current->comm, task_pid_nr(current));
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800140}
141
Andrey Ryabininbebf56a2015-02-13 14:40:17 -0800142static inline bool kernel_or_module_addr(const void *addr)
143{
Aneesh Kumar K.V527f2152015-11-05 18:50:46 -0800144 if (addr >= (void *)_stext && addr < (void *)_end)
145 return true;
146 if (is_module_address((unsigned long)addr))
147 return true;
148 return false;
Andrey Ryabininbebf56a2015-02-13 14:40:17 -0800149}
150
151static inline bool init_task_stack_addr(const void *addr)
152{
153 return addr >= (void *)&init_thread_union.stack &&
154 (addr <= (void *)&init_thread_union.stack +
155 sizeof(init_thread_union.stack));
156}
157
Andrey Ryabinin7e088972016-08-02 14:02:55 -0700158static DEFINE_SPINLOCK(report_lock);
159
160static void kasan_start_report(unsigned long *flags)
161{
162 /*
163 * Make sure we don't end up in loop.
164 */
165 kasan_disable_current();
166 spin_lock_irqsave(&report_lock, *flags);
167 pr_err("==================================================================\n");
168}
169
170static void kasan_end_report(unsigned long *flags)
171{
172 pr_err("==================================================================\n");
173 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
174 spin_unlock_irqrestore(&report_lock, *flags);
Dmitry Vyukov5c5c1f32016-12-12 16:44:53 -0800175 if (panic_on_warn)
176 panic("panic_on_warn set ...\n");
Andrey Ryabinin7e088972016-08-02 14:02:55 -0700177 kasan_enable_current();
178}
179
Andrey Konovalovb6b72f42017-05-03 14:56:31 -0700180static void print_track(struct kasan_track *track, const char *prefix)
Alexander Potapenko7ed2f9e2016-03-25 14:21:59 -0700181{
Andrey Konovalovb6b72f42017-05-03 14:56:31 -0700182 pr_err("%s by task %u:\n", prefix, track->pid);
Alexander Potapenkocd110162016-03-25 14:22:08 -0700183 if (track->stack) {
184 struct stack_trace trace;
185
186 depot_fetch_stack(track->stack, &trace);
187 print_stack_trace(&trace, 0);
188 } else {
189 pr_err("(stack is not available)\n");
190 }
Alexander Potapenko7ed2f9e2016-03-25 14:21:59 -0700191}
192
Andrey Konovalovdb429f12017-05-03 14:56:34 -0700193static struct page *addr_to_page(const void *addr)
194{
195 if ((addr >= (void *)PAGE_OFFSET) &&
196 (addr < high_memory))
197 return virt_to_head_page(addr);
198 return NULL;
199}
200
201static void describe_object(struct kmem_cache *cache, void *object)
Alexander Potapenko7ed2f9e2016-03-25 14:21:59 -0700202{
203 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
Alexander Potapenko7ed2f9e2016-03-25 14:21:59 -0700204
Andrey Ryabinin47b5c2a2016-08-02 14:02:49 -0700205 pr_err("Object at %p, in cache %s size: %d\n", object, cache->name,
206 cache->object_size);
207
Alexander Potapenko7ed2f9e2016-03-25 14:21:59 -0700208 if (!(cache->flags & SLAB_KASAN))
209 return;
Andrey Ryabininb3cbd9b2016-08-02 14:02:52 -0700210
Andrey Konovalovb6b72f42017-05-03 14:56:31 -0700211 print_track(&alloc_info->alloc_track, "Allocated");
212 print_track(&alloc_info->free_track, "Freed");
Alexander Potapenko7ed2f9e2016-03-25 14:21:59 -0700213}
Alexander Potapenko7ed2f9e2016-03-25 14:21:59 -0700214
Andrey Ryabinin7e088972016-08-02 14:02:55 -0700215void kasan_report_double_free(struct kmem_cache *cache, void *object,
216 s8 shadow)
217{
218 unsigned long flags;
219
220 kasan_start_report(&flags);
221 pr_err("BUG: Double free or freeing an invalid pointer\n");
222 pr_err("Unexpected shadow byte: 0x%hhX\n", shadow);
Andrey Konovalovdb429f12017-05-03 14:56:34 -0700223 dump_stack();
224 describe_object(cache, object);
Andrey Ryabinin7e088972016-08-02 14:02:55 -0700225 kasan_end_report(&flags);
226}
227
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800228static void print_address_description(struct kasan_access_info *info)
229{
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -0800230 const void *addr = info->access_addr;
Andrey Konovalovdb429f12017-05-03 14:56:34 -0700231 struct page *page = addr_to_page(addr);
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -0800232
Andrey Konovalovdb429f12017-05-03 14:56:34 -0700233 if (page)
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -0800234 dump_page(page, "kasan: bad access detected");
Andrey Konovalovdb429f12017-05-03 14:56:34 -0700235
236 dump_stack();
237
238 if (page && PageSlab(page)) {
239 struct kmem_cache *cache = page->slab_cache;
240 void *object = nearest_obj(cache, page, (void *)addr);
241
242 describe_object(cache, object);
Andrey Ryabininb8c73fc2015-02-13 14:39:28 -0800243 }
244
Andrey Ryabininbebf56a2015-02-13 14:40:17 -0800245 if (kernel_or_module_addr(addr)) {
246 if (!init_task_stack_addr(addr))
247 pr_err("Address belongs to variable %pS\n", addr);
248 }
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800249}
250
251static bool row_is_guilty(const void *row, const void *guilty)
252{
253 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
254}
255
256static int shadow_pointer_offset(const void *row, const void *shadow)
257{
258 /* The length of ">ff00ff00ff00ff00: " is
259 * 3 + (BITS_PER_LONG/8)*2 chars.
260 */
261 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
262 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
263}
264
265static void print_shadow_for_address(const void *addr)
266{
267 int i;
268 const void *shadow = kasan_mem_to_shadow(addr);
269 const void *shadow_row;
270
271 shadow_row = (void *)round_down((unsigned long)shadow,
272 SHADOW_BYTES_PER_ROW)
273 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
274
275 pr_err("Memory state around the buggy address:\n");
276
277 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
278 const void *kaddr = kasan_shadow_to_mem(shadow_row);
279 char buffer[4 + (BITS_PER_LONG/8)*2];
Aneesh Kumar K.Vf2377d42015-11-05 18:50:48 -0800280 char shadow_buf[SHADOW_BYTES_PER_ROW];
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800281
282 snprintf(buffer, sizeof(buffer),
283 (i == 0) ? ">%p: " : " %p: ", kaddr);
Aneesh Kumar K.Vf2377d42015-11-05 18:50:48 -0800284 /*
285 * We should not pass a shadow pointer to generic
286 * function, because generic functions may try to
287 * access kasan mapping for the passed address.
288 */
Aneesh Kumar K.Vf2377d42015-11-05 18:50:48 -0800289 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800290 print_hex_dump(KERN_ERR, buffer,
291 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
Aneesh Kumar K.Vf2377d42015-11-05 18:50:48 -0800292 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800293
294 if (row_is_guilty(shadow_row, shadow))
295 pr_err("%*c\n",
296 shadow_pointer_offset(shadow_row, shadow),
297 '^');
298
299 shadow_row += SHADOW_BYTES_PER_ROW;
300 }
301}
302
Andrey Konovalove91210762015-11-05 18:50:55 -0800303static void kasan_report_error(struct kasan_access_info *info)
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800304{
305 unsigned long flags;
306
Andrey Ryabinin7e088972016-08-02 14:02:55 -0700307 kasan_start_report(&flags);
308
Andrey Konovalov7d418f72017-05-03 14:56:28 -0700309 print_error_description(info);
310
Andrey Konovalov5e82cd12017-05-03 14:56:25 -0700311 if (!addr_has_shadow(info)) {
Andrey Konovalove91210762015-11-05 18:50:55 -0800312 dump_stack();
313 } else {
Andrey Konovalove91210762015-11-05 18:50:55 -0800314 print_address_description(info);
315 print_shadow_for_address(info->first_bad_addr);
316 }
Andrey Ryabinin7e088972016-08-02 14:02:55 -0700317
318 kasan_end_report(&flags);
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800319}
320
Mark Rutlandb0845ce2017-03-31 15:12:04 -0700321static unsigned long kasan_flags;
322
323#define KASAN_BIT_REPORTED 0
324#define KASAN_BIT_MULTI_SHOT 1
325
326bool kasan_save_enable_multi_shot(void)
327{
328 return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
329}
330EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
331
332void kasan_restore_multi_shot(bool enabled)
333{
334 if (!enabled)
335 clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
336}
337EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
338
339static int __init kasan_set_multi_shot(char *str)
340{
341 set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
342 return 1;
343}
344__setup("kasan_multi_shot", kasan_set_multi_shot);
345
346static inline bool kasan_report_enabled(void)
347{
348 if (current->kasan_depth)
349 return false;
350 if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
351 return true;
352 return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
353}
354
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800355void kasan_report(unsigned long addr, size_t size,
356 bool is_write, unsigned long ip)
357{
358 struct kasan_access_info info;
359
Aneesh Kumar K.V0ba86632015-11-05 18:50:43 -0800360 if (likely(!kasan_report_enabled()))
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800361 return;
362
Peter Zijlstra4f40c6e2017-02-03 13:13:12 -0800363 disable_trace_on_warning();
364
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800365 info.access_addr = (void *)addr;
366 info.access_size = size;
367 info.is_write = is_write;
368 info.ip = ip;
Andrey Konovalove91210762015-11-05 18:50:55 -0800369
Andrey Ryabinin0b24bec2015-02-13 14:39:17 -0800370 kasan_report_error(&info);
371}
372
373
374#define DEFINE_ASAN_REPORT_LOAD(size) \
375void __asan_report_load##size##_noabort(unsigned long addr) \
376{ \
377 kasan_report(addr, size, false, _RET_IP_); \
378} \
379EXPORT_SYMBOL(__asan_report_load##size##_noabort)
380
381#define DEFINE_ASAN_REPORT_STORE(size) \
382void __asan_report_store##size##_noabort(unsigned long addr) \
383{ \
384 kasan_report(addr, size, true, _RET_IP_); \
385} \
386EXPORT_SYMBOL(__asan_report_store##size##_noabort)
387
388DEFINE_ASAN_REPORT_LOAD(1);
389DEFINE_ASAN_REPORT_LOAD(2);
390DEFINE_ASAN_REPORT_LOAD(4);
391DEFINE_ASAN_REPORT_LOAD(8);
392DEFINE_ASAN_REPORT_LOAD(16);
393DEFINE_ASAN_REPORT_STORE(1);
394DEFINE_ASAN_REPORT_STORE(2);
395DEFINE_ASAN_REPORT_STORE(4);
396DEFINE_ASAN_REPORT_STORE(8);
397DEFINE_ASAN_REPORT_STORE(16);
398
399void __asan_report_load_n_noabort(unsigned long addr, size_t size)
400{
401 kasan_report(addr, size, false, _RET_IP_);
402}
403EXPORT_SYMBOL(__asan_report_load_n_noabort);
404
405void __asan_report_store_n_noabort(unsigned long addr, size_t size)
406{
407 kasan_report(addr, size, true, _RET_IP_);
408}
409EXPORT_SYMBOL(__asan_report_store_n_noabort);