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e886bf9d | 1 | // SPDX-License-Identifier: GPL-2.0 |
0b24becc | 2 | /* |
11cd3cd6 | 3 | * This file contains common generic and tag-based KASAN error reporting code. |
0b24becc AR |
4 | * |
5 | * Copyright (c) 2014 Samsung Electronics Co., Ltd. | |
2baf9e89 | 6 | * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> |
0b24becc | 7 | * |
5d0926ef | 8 | * Some code borrowed from https://github.com/xairy/kasan-prototype by |
5f21f3a8 | 9 | * Andrey Konovalov <andreyknvl@gmail.com> |
0b24becc AR |
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 | ||
b0845ce5 | 17 | #include <linux/bitops.h> |
4f40c6e5 | 18 | #include <linux/ftrace.h> |
b0845ce5 | 19 | #include <linux/init.h> |
0b24becc AR |
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> | |
cd11016e | 25 | #include <linux/stackdepot.h> |
0b24becc AR |
26 | #include <linux/stacktrace.h> |
27 | #include <linux/string.h> | |
28 | #include <linux/types.h> | |
29 | #include <linux/kasan.h> | |
527f215b | 30 | #include <linux/module.h> |
e8969219 | 31 | #include <linux/sched/task_stack.h> |
0b24becc | 32 | |
bebf56a1 AR |
33 | #include <asm/sections.h> |
34 | ||
0b24becc | 35 | #include "kasan.h" |
0316bec2 | 36 | #include "../slab.h" |
0b24becc AR |
37 | |
38 | /* Shadow layout customization. */ | |
39 | #define SHADOW_BYTES_PER_BLOCK 1 | |
40 | #define SHADOW_BLOCKS_PER_ROW 16 | |
41 | #define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK) | |
42 | #define SHADOW_ROWS_AROUND_ADDR 2 | |
43 | ||
11cd3cd6 | 44 | static unsigned long kasan_flags; |
0b24becc | 45 | |
11cd3cd6 AK |
46 | #define KASAN_BIT_REPORTED 0 |
47 | #define KASAN_BIT_MULTI_SHOT 1 | |
5e82cd12 | 48 | |
11cd3cd6 | 49 | bool kasan_save_enable_multi_shot(void) |
0b24becc | 50 | { |
11cd3cd6 | 51 | return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); |
5e82cd12 | 52 | } |
11cd3cd6 | 53 | EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot); |
5e82cd12 | 54 | |
11cd3cd6 | 55 | void kasan_restore_multi_shot(bool enabled) |
5e82cd12 | 56 | { |
11cd3cd6 AK |
57 | if (!enabled) |
58 | clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); | |
5e82cd12 | 59 | } |
11cd3cd6 | 60 | EXPORT_SYMBOL_GPL(kasan_restore_multi_shot); |
5e82cd12 | 61 | |
11cd3cd6 | 62 | static int __init kasan_set_multi_shot(char *str) |
7d418f7b | 63 | { |
11cd3cd6 AK |
64 | set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); |
65 | return 1; | |
7d418f7b | 66 | } |
11cd3cd6 | 67 | __setup("kasan_multi_shot", kasan_set_multi_shot); |
7d418f7b | 68 | |
121e8f81 | 69 | static void print_error_description(struct kasan_access_info *info) |
5e82cd12 | 70 | { |
7f0a84c2 | 71 | pr_err("BUG: KASAN: %s in %pS\n", |
121e8f81 | 72 | get_bug_type(info), (void *)info->ip); |
6424f6bb | 73 | pr_err("%s of size %zu at addr %px by task %s/%d\n", |
7d418f7b | 74 | info->is_write ? "Write" : "Read", info->access_size, |
7f0a84c2 | 75 | info->access_addr, current->comm, task_pid_nr(current)); |
0b24becc AR |
76 | } |
77 | ||
7e088978 AR |
78 | static DEFINE_SPINLOCK(report_lock); |
79 | ||
11cd3cd6 | 80 | static void start_report(unsigned long *flags) |
7e088978 AR |
81 | { |
82 | /* | |
83 | * Make sure we don't end up in loop. | |
84 | */ | |
85 | kasan_disable_current(); | |
86 | spin_lock_irqsave(&report_lock, *flags); | |
87 | pr_err("==================================================================\n"); | |
88 | } | |
89 | ||
11cd3cd6 | 90 | static void end_report(unsigned long *flags) |
7e088978 AR |
91 | { |
92 | pr_err("==================================================================\n"); | |
93 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); | |
94 | spin_unlock_irqrestore(&report_lock, *flags); | |
5c5c1f36 DV |
95 | if (panic_on_warn) |
96 | panic("panic_on_warn set ...\n"); | |
7e088978 AR |
97 | kasan_enable_current(); |
98 | } | |
99 | ||
b6b72f49 | 100 | static void print_track(struct kasan_track *track, const char *prefix) |
7ed2f9e6 | 101 | { |
b6b72f49 | 102 | pr_err("%s by task %u:\n", prefix, track->pid); |
cd11016e | 103 | if (track->stack) { |
880e049c TG |
104 | unsigned long *entries; |
105 | unsigned int nr_entries; | |
cd11016e | 106 | |
880e049c TG |
107 | nr_entries = stack_depot_fetch(track->stack, &entries); |
108 | stack_trace_print(entries, nr_entries, 0); | |
cd11016e AP |
109 | } else { |
110 | pr_err("(stack is not available)\n"); | |
111 | } | |
7ed2f9e6 AP |
112 | } |
113 | ||
ae8f06b3 | 114 | struct page *kasan_addr_to_page(const void *addr) |
db429f16 AK |
115 | { |
116 | if ((addr >= (void *)PAGE_OFFSET) && | |
117 | (addr < high_memory)) | |
118 | return virt_to_head_page(addr); | |
119 | return NULL; | |
120 | } | |
121 | ||
0c06f1f8 AK |
122 | static void describe_object_addr(struct kmem_cache *cache, void *object, |
123 | const void *addr) | |
7ed2f9e6 | 124 | { |
0c06f1f8 AK |
125 | unsigned long access_addr = (unsigned long)addr; |
126 | unsigned long object_addr = (unsigned long)object; | |
127 | const char *rel_type; | |
128 | int rel_bytes; | |
7ed2f9e6 | 129 | |
6424f6bb | 130 | pr_err("The buggy address belongs to the object at %px\n" |
0c06f1f8 AK |
131 | " which belongs to the cache %s of size %d\n", |
132 | object, cache->name, cache->object_size); | |
47b5c2a0 | 133 | |
0c06f1f8 | 134 | if (!addr) |
7ed2f9e6 | 135 | return; |
b3cbd9bf | 136 | |
0c06f1f8 AK |
137 | if (access_addr < object_addr) { |
138 | rel_type = "to the left"; | |
139 | rel_bytes = object_addr - access_addr; | |
140 | } else if (access_addr >= object_addr + cache->object_size) { | |
141 | rel_type = "to the right"; | |
142 | rel_bytes = access_addr - (object_addr + cache->object_size); | |
143 | } else { | |
144 | rel_type = "inside"; | |
145 | rel_bytes = access_addr - object_addr; | |
146 | } | |
147 | ||
148 | pr_err("The buggy address is located %d bytes %s of\n" | |
6424f6bb | 149 | " %d-byte region [%px, %px)\n", |
0c06f1f8 AK |
150 | rel_bytes, rel_type, cache->object_size, (void *)object_addr, |
151 | (void *)(object_addr + cache->object_size)); | |
152 | } | |
153 | ||
ae8f06b3 WW |
154 | static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, |
155 | void *object, u8 tag) | |
156 | { | |
157 | struct kasan_alloc_meta *alloc_meta; | |
158 | int i = 0; | |
159 | ||
160 | alloc_meta = get_alloc_info(cache, object); | |
161 | ||
162 | #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY | |
163 | for (i = 0; i < KASAN_NR_FREE_STACKS; i++) { | |
164 | if (alloc_meta->free_pointer_tag[i] == tag) | |
165 | break; | |
166 | } | |
167 | if (i == KASAN_NR_FREE_STACKS) | |
168 | i = alloc_meta->free_track_idx; | |
169 | #endif | |
170 | ||
171 | return &alloc_meta->free_track[i]; | |
172 | } | |
173 | ||
0c06f1f8 | 174 | static void describe_object(struct kmem_cache *cache, void *object, |
ae8f06b3 | 175 | const void *addr, u8 tag) |
0c06f1f8 AK |
176 | { |
177 | struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); | |
178 | ||
179 | if (cache->flags & SLAB_KASAN) { | |
ae8f06b3 WW |
180 | struct kasan_track *free_track; |
181 | ||
0c06f1f8 | 182 | print_track(&alloc_info->alloc_track, "Allocated"); |
b1938599 | 183 | pr_err("\n"); |
ae8f06b3 WW |
184 | free_track = kasan_get_free_track(cache, object, tag); |
185 | print_track(free_track, "Freed"); | |
b1938599 | 186 | pr_err("\n"); |
0c06f1f8 AK |
187 | } |
188 | ||
189 | describe_object_addr(cache, object, addr); | |
7ed2f9e6 | 190 | } |
7ed2f9e6 | 191 | |
11cd3cd6 AK |
192 | static inline bool kernel_or_module_addr(const void *addr) |
193 | { | |
194 | if (addr >= (void *)_stext && addr < (void *)_end) | |
195 | return true; | |
196 | if (is_module_address((unsigned long)addr)) | |
197 | return true; | |
198 | return false; | |
199 | } | |
200 | ||
201 | static inline bool init_task_stack_addr(const void *addr) | |
202 | { | |
203 | return addr >= (void *)&init_thread_union.stack && | |
204 | (addr <= (void *)&init_thread_union.stack + | |
205 | sizeof(init_thread_union.stack)); | |
206 | } | |
207 | ||
e8969219 ME |
208 | static bool __must_check tokenize_frame_descr(const char **frame_descr, |
209 | char *token, size_t max_tok_len, | |
210 | unsigned long *value) | |
211 | { | |
212 | const char *sep = strchr(*frame_descr, ' '); | |
213 | ||
214 | if (sep == NULL) | |
215 | sep = *frame_descr + strlen(*frame_descr); | |
216 | ||
217 | if (token != NULL) { | |
218 | const size_t tok_len = sep - *frame_descr; | |
219 | ||
220 | if (tok_len + 1 > max_tok_len) { | |
221 | pr_err("KASAN internal error: frame description too long: %s\n", | |
222 | *frame_descr); | |
223 | return false; | |
224 | } | |
225 | ||
226 | /* Copy token (+ 1 byte for '\0'). */ | |
227 | strlcpy(token, *frame_descr, tok_len + 1); | |
228 | } | |
229 | ||
230 | /* Advance frame_descr past separator. */ | |
231 | *frame_descr = sep + 1; | |
232 | ||
233 | if (value != NULL && kstrtoul(token, 10, value)) { | |
234 | pr_err("KASAN internal error: not a valid number: %s\n", token); | |
235 | return false; | |
236 | } | |
237 | ||
238 | return true; | |
239 | } | |
240 | ||
241 | static void print_decoded_frame_descr(const char *frame_descr) | |
242 | { | |
243 | /* | |
244 | * We need to parse the following string: | |
245 | * "n alloc_1 alloc_2 ... alloc_n" | |
246 | * where alloc_i looks like | |
247 | * "offset size len name" | |
248 | * or "offset size len name:line". | |
249 | */ | |
250 | ||
251 | char token[64]; | |
252 | unsigned long num_objects; | |
253 | ||
254 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
255 | &num_objects)) | |
256 | return; | |
257 | ||
258 | pr_err("\n"); | |
259 | pr_err("this frame has %lu %s:\n", num_objects, | |
260 | num_objects == 1 ? "object" : "objects"); | |
261 | ||
262 | while (num_objects--) { | |
263 | unsigned long offset; | |
264 | unsigned long size; | |
265 | ||
266 | /* access offset */ | |
267 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
268 | &offset)) | |
269 | return; | |
270 | /* access size */ | |
271 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
272 | &size)) | |
273 | return; | |
274 | /* name length (unused) */ | |
275 | if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) | |
276 | return; | |
277 | /* object name */ | |
278 | if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), | |
279 | NULL)) | |
280 | return; | |
281 | ||
282 | /* Strip line number; without filename it's not very helpful. */ | |
283 | strreplace(token, ':', '\0'); | |
284 | ||
285 | /* Finally, print object information. */ | |
286 | pr_err(" [%lu, %lu) '%s'", offset, offset + size, token); | |
287 | } | |
288 | } | |
289 | ||
290 | static bool __must_check get_address_stack_frame_info(const void *addr, | |
291 | unsigned long *offset, | |
292 | const char **frame_descr, | |
293 | const void **frame_pc) | |
294 | { | |
295 | unsigned long aligned_addr; | |
296 | unsigned long mem_ptr; | |
297 | const u8 *shadow_bottom; | |
298 | const u8 *shadow_ptr; | |
299 | const unsigned long *frame; | |
300 | ||
301 | BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROWSUP)); | |
302 | ||
303 | /* | |
304 | * NOTE: We currently only support printing frame information for | |
305 | * accesses to the task's own stack. | |
306 | */ | |
307 | if (!object_is_on_stack(addr)) | |
308 | return false; | |
309 | ||
310 | aligned_addr = round_down((unsigned long)addr, sizeof(long)); | |
311 | mem_ptr = round_down(aligned_addr, KASAN_SHADOW_SCALE_SIZE); | |
312 | shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); | |
313 | shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); | |
314 | ||
315 | while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { | |
316 | shadow_ptr--; | |
317 | mem_ptr -= KASAN_SHADOW_SCALE_SIZE; | |
318 | } | |
319 | ||
320 | while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { | |
321 | shadow_ptr--; | |
322 | mem_ptr -= KASAN_SHADOW_SCALE_SIZE; | |
323 | } | |
324 | ||
325 | if (shadow_ptr < shadow_bottom) | |
326 | return false; | |
327 | ||
328 | frame = (const unsigned long *)(mem_ptr + KASAN_SHADOW_SCALE_SIZE); | |
329 | if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) { | |
330 | pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n", | |
331 | frame[0]); | |
332 | return false; | |
333 | } | |
334 | ||
335 | *offset = (unsigned long)addr - (unsigned long)frame; | |
336 | *frame_descr = (const char *)frame[1]; | |
337 | *frame_pc = (void *)frame[2]; | |
338 | ||
339 | return true; | |
340 | } | |
341 | ||
342 | static void print_address_stack_frame(const void *addr) | |
343 | { | |
344 | unsigned long offset; | |
345 | const char *frame_descr; | |
346 | const void *frame_pc; | |
347 | ||
348 | if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) | |
349 | return; | |
350 | ||
351 | if (!get_address_stack_frame_info(addr, &offset, &frame_descr, | |
352 | &frame_pc)) | |
353 | return; | |
354 | ||
355 | /* | |
356 | * get_address_stack_frame_info only returns true if the given addr is | |
357 | * on the current task's stack. | |
358 | */ | |
359 | pr_err("\n"); | |
360 | pr_err("addr %px is located in stack of task %s/%d at offset %lu in frame:\n", | |
361 | addr, current->comm, task_pid_nr(current), offset); | |
362 | pr_err(" %pS\n", frame_pc); | |
363 | ||
364 | if (!frame_descr) | |
365 | return; | |
366 | ||
367 | print_decoded_frame_descr(frame_descr); | |
368 | } | |
369 | ||
ae8f06b3 | 370 | static void print_address_description(void *addr, u8 tag) |
0b24becc | 371 | { |
ae8f06b3 | 372 | struct page *page = kasan_addr_to_page(addr); |
b8c73fc2 | 373 | |
db429f16 | 374 | dump_stack(); |
b1938599 | 375 | pr_err("\n"); |
db429f16 AK |
376 | |
377 | if (page && PageSlab(page)) { | |
378 | struct kmem_cache *cache = page->slab_cache; | |
0c06f1f8 | 379 | void *object = nearest_obj(cache, page, addr); |
db429f16 | 380 | |
ae8f06b3 | 381 | describe_object(cache, object, addr, tag); |
b8c73fc2 AR |
382 | } |
383 | ||
430a05f9 AK |
384 | if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) { |
385 | pr_err("The buggy address belongs to the variable:\n"); | |
386 | pr_err(" %pS\n", addr); | |
387 | } | |
388 | ||
389 | if (page) { | |
390 | pr_err("The buggy address belongs to the page:\n"); | |
391 | dump_page(page, "kasan: bad access detected"); | |
bebf56a1 | 392 | } |
e8969219 ME |
393 | |
394 | print_address_stack_frame(addr); | |
0b24becc AR |
395 | } |
396 | ||
397 | static bool row_is_guilty(const void *row, const void *guilty) | |
398 | { | |
399 | return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW); | |
400 | } | |
401 | ||
402 | static int shadow_pointer_offset(const void *row, const void *shadow) | |
403 | { | |
404 | /* The length of ">ff00ff00ff00ff00: " is | |
405 | * 3 + (BITS_PER_LONG/8)*2 chars. | |
406 | */ | |
407 | return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 + | |
408 | (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1; | |
409 | } | |
410 | ||
411 | static void print_shadow_for_address(const void *addr) | |
412 | { | |
413 | int i; | |
414 | const void *shadow = kasan_mem_to_shadow(addr); | |
415 | const void *shadow_row; | |
416 | ||
417 | shadow_row = (void *)round_down((unsigned long)shadow, | |
418 | SHADOW_BYTES_PER_ROW) | |
419 | - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW; | |
420 | ||
421 | pr_err("Memory state around the buggy address:\n"); | |
422 | ||
423 | for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) { | |
424 | const void *kaddr = kasan_shadow_to_mem(shadow_row); | |
425 | char buffer[4 + (BITS_PER_LONG/8)*2]; | |
f2377d4e | 426 | char shadow_buf[SHADOW_BYTES_PER_ROW]; |
0b24becc AR |
427 | |
428 | snprintf(buffer, sizeof(buffer), | |
6424f6bb | 429 | (i == 0) ? ">%px: " : " %px: ", kaddr); |
f2377d4e AK |
430 | /* |
431 | * We should not pass a shadow pointer to generic | |
432 | * function, because generic functions may try to | |
433 | * access kasan mapping for the passed address. | |
434 | */ | |
f2377d4e | 435 | memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW); |
0b24becc AR |
436 | print_hex_dump(KERN_ERR, buffer, |
437 | DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1, | |
f2377d4e | 438 | shadow_buf, SHADOW_BYTES_PER_ROW, 0); |
0b24becc AR |
439 | |
440 | if (row_is_guilty(shadow_row, shadow)) | |
441 | pr_err("%*c\n", | |
442 | shadow_pointer_offset(shadow_row, shadow), | |
443 | '^'); | |
444 | ||
445 | shadow_row += SHADOW_BYTES_PER_ROW; | |
446 | } | |
447 | } | |
448 | ||
11cd3cd6 AK |
449 | static bool report_enabled(void) |
450 | { | |
451 | if (current->kasan_depth) | |
452 | return false; | |
453 | if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) | |
454 | return true; | |
455 | return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); | |
456 | } | |
457 | ||
ee3ce779 | 458 | void kasan_report_invalid_free(void *object, unsigned long ip) |
5ab6d91a AK |
459 | { |
460 | unsigned long flags; | |
ae8f06b3 | 461 | u8 tag = get_tag(object); |
5ab6d91a | 462 | |
ae8f06b3 | 463 | object = reset_tag(object); |
11cd3cd6 | 464 | start_report(&flags); |
ee3ce779 | 465 | pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip); |
ae8f06b3 | 466 | print_tags(tag, object); |
b1938599 | 467 | pr_err("\n"); |
ae8f06b3 | 468 | print_address_description(object, tag); |
b1938599 | 469 | pr_err("\n"); |
5ab6d91a | 470 | print_shadow_for_address(object); |
11cd3cd6 | 471 | end_report(&flags); |
5ab6d91a AK |
472 | } |
473 | ||
57b78a62 | 474 | void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) |
0b24becc AR |
475 | { |
476 | struct kasan_access_info info; | |
121e8f81 AK |
477 | void *tagged_addr; |
478 | void *untagged_addr; | |
479 | unsigned long flags; | |
0b24becc | 480 | |
11cd3cd6 | 481 | if (likely(!report_enabled())) |
0b24becc AR |
482 | return; |
483 | ||
4f40c6e5 PZ |
484 | disable_trace_on_warning(); |
485 | ||
121e8f81 AK |
486 | tagged_addr = (void *)addr; |
487 | untagged_addr = reset_tag(tagged_addr); | |
488 | ||
489 | info.access_addr = tagged_addr; | |
490 | if (addr_has_shadow(untagged_addr)) | |
491 | info.first_bad_addr = find_first_bad_addr(tagged_addr, size); | |
492 | else | |
493 | info.first_bad_addr = untagged_addr; | |
0b24becc AR |
494 | info.access_size = size; |
495 | info.is_write = is_write; | |
496 | info.ip = ip; | |
e9121076 | 497 | |
121e8f81 AK |
498 | start_report(&flags); |
499 | ||
500 | print_error_description(&info); | |
501 | if (addr_has_shadow(untagged_addr)) | |
502 | print_tags(get_tag(tagged_addr), info.first_bad_addr); | |
503 | pr_err("\n"); | |
504 | ||
505 | if (addr_has_shadow(untagged_addr)) { | |
ae8f06b3 | 506 | print_address_description(untagged_addr, get_tag(tagged_addr)); |
121e8f81 AK |
507 | pr_err("\n"); |
508 | print_shadow_for_address(info.first_bad_addr); | |
509 | } else { | |
510 | dump_stack(); | |
511 | } | |
512 | ||
513 | end_report(&flags); | |
0b24becc | 514 | } |