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1 /*
2 * mm/kmemleak.c
3 *
4 * Copyright (C) 2008 ARM Limited
5 * Written by Catalin Marinas <catalin.marinas@arm.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 *
20 *
21 * For more information on the algorithm and kmemleak usage, please see
22 * Documentation/kmemleak.txt.
23 *
24 * Notes on locking
25 * ----------------
26 *
27 * The following locks and mutexes are used by kmemleak:
28 *
29 * - kmemleak_lock (rwlock): protects the object_list modifications and
30 * accesses to the object_tree_root. The object_list is the main list
31 * holding the metadata (struct kmemleak_object) for the allocated memory
32 * blocks. The object_tree_root is a priority search tree used to look-up
33 * metadata based on a pointer to the corresponding memory block. The
34 * kmemleak_object structures are added to the object_list and
35 * object_tree_root in the create_object() function called from the
36 * kmemleak_alloc() callback and removed in delete_object() called from the
37 * kmemleak_free() callback
38 * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
39 * the metadata (e.g. count) are protected by this lock. Note that some
40 * members of this structure may be protected by other means (atomic or
41 * kmemleak_lock). This lock is also held when scanning the corresponding
42 * memory block to avoid the kernel freeing it via the kmemleak_free()
43 * callback. This is less heavyweight than holding a global lock like
44 * kmemleak_lock during scanning
45 * - scan_mutex (mutex): ensures that only one thread may scan the memory for
46 * unreferenced objects at a time. The gray_list contains the objects which
47 * are already referenced or marked as false positives and need to be
48 * scanned. This list is only modified during a scanning episode when the
49 * scan_mutex is held. At the end of a scan, the gray_list is always empty.
50 * Note that the kmemleak_object.use_count is incremented when an object is
51 * added to the gray_list and therefore cannot be freed. This mutex also
52 * prevents multiple users of the "kmemleak" debugfs file together with
53 * modifications to the memory scanning parameters including the scan_thread
54 * pointer
55 *
56 * The kmemleak_object structures have a use_count incremented or decremented
57 * using the get_object()/put_object() functions. When the use_count becomes
58 * 0, this count can no longer be incremented and put_object() schedules the
59 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
60 * function must be protected by rcu_read_lock() to avoid accessing a freed
61 * structure.
62 */
63
64 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
65
66 #include <linux/init.h>
67 #include <linux/kernel.h>
68 #include <linux/list.h>
69 #include <linux/sched.h>
70 #include <linux/jiffies.h>
71 #include <linux/delay.h>
72 #include <linux/export.h>
73 #include <linux/kthread.h>
74 #include <linux/prio_tree.h>
75 #include <linux/fs.h>
76 #include <linux/debugfs.h>
77 #include <linux/seq_file.h>
78 #include <linux/cpumask.h>
79 #include <linux/spinlock.h>
80 #include <linux/mutex.h>
81 #include <linux/rcupdate.h>
82 #include <linux/stacktrace.h>
83 #include <linux/cache.h>
84 #include <linux/percpu.h>
85 #include <linux/hardirq.h>
86 #include <linux/mmzone.h>
87 #include <linux/slab.h>
88 #include <linux/thread_info.h>
89 #include <linux/err.h>
90 #include <linux/uaccess.h>
91 #include <linux/string.h>
92 #include <linux/nodemask.h>
93 #include <linux/mm.h>
94 #include <linux/workqueue.h>
95 #include <linux/crc32.h>
96
97 #include <asm/sections.h>
98 #include <asm/processor.h>
99 #include <linux/atomic.h>
100
101 #include <linux/kmemcheck.h>
102 #include <linux/kmemleak.h>
103 #include <linux/memory_hotplug.h>
104
105 /*
106 * Kmemleak configuration and common defines.
107 */
108 #define MAX_TRACE 16 /* stack trace length */
109 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
110 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
111 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
112 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
113
114 #define BYTES_PER_POINTER sizeof(void *)
115
116 /* GFP bitmask for kmemleak internal allocations */
117 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
118 __GFP_NORETRY | __GFP_NOMEMALLOC | \
119 __GFP_NOWARN)
120
121 /* scanning area inside a memory block */
122 struct kmemleak_scan_area {
123 struct hlist_node node;
124 unsigned long start;
125 size_t size;
126 };
127
128 #define KMEMLEAK_GREY 0
129 #define KMEMLEAK_BLACK -1
130
131 /*
132 * Structure holding the metadata for each allocated memory block.
133 * Modifications to such objects should be made while holding the
134 * object->lock. Insertions or deletions from object_list, gray_list or
135 * tree_node are already protected by the corresponding locks or mutex (see
136 * the notes on locking above). These objects are reference-counted
137 * (use_count) and freed using the RCU mechanism.
138 */
139 struct kmemleak_object {
140 spinlock_t lock;
141 unsigned long flags; /* object status flags */
142 struct list_head object_list;
143 struct list_head gray_list;
144 struct prio_tree_node tree_node;
145 struct rcu_head rcu; /* object_list lockless traversal */
146 /* object usage count; object freed when use_count == 0 */
147 atomic_t use_count;
148 unsigned long pointer;
149 size_t size;
150 /* minimum number of a pointers found before it is considered leak */
151 int min_count;
152 /* the total number of pointers found pointing to this object */
153 int count;
154 /* checksum for detecting modified objects */
155 u32 checksum;
156 /* memory ranges to be scanned inside an object (empty for all) */
157 struct hlist_head area_list;
158 unsigned long trace[MAX_TRACE];
159 unsigned int trace_len;
160 unsigned long jiffies; /* creation timestamp */
161 pid_t pid; /* pid of the current task */
162 char comm[TASK_COMM_LEN]; /* executable name */
163 };
164
165 /* flag representing the memory block allocation status */
166 #define OBJECT_ALLOCATED (1 << 0)
167 /* flag set after the first reporting of an unreference object */
168 #define OBJECT_REPORTED (1 << 1)
169 /* flag set to not scan the object */
170 #define OBJECT_NO_SCAN (1 << 2)
171
172 /* number of bytes to print per line; must be 16 or 32 */
173 #define HEX_ROW_SIZE 16
174 /* number of bytes to print at a time (1, 2, 4, 8) */
175 #define HEX_GROUP_SIZE 1
176 /* include ASCII after the hex output */
177 #define HEX_ASCII 1
178 /* max number of lines to be printed */
179 #define HEX_MAX_LINES 2
180
181 /* the list of all allocated objects */
182 static LIST_HEAD(object_list);
183 /* the list of gray-colored objects (see color_gray comment below) */
184 static LIST_HEAD(gray_list);
185 /* prio search tree for object boundaries */
186 static struct prio_tree_root object_tree_root;
187 /* rw_lock protecting the access to object_list and prio_tree_root */
188 static DEFINE_RWLOCK(kmemleak_lock);
189
190 /* allocation caches for kmemleak internal data */
191 static struct kmem_cache *object_cache;
192 static struct kmem_cache *scan_area_cache;
193
194 /* set if tracing memory operations is enabled */
195 static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
196 /* set in the late_initcall if there were no errors */
197 static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
198 /* enables or disables early logging of the memory operations */
199 static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
200 /* set if a kmemleak warning was issued */
201 static atomic_t kmemleak_warning = ATOMIC_INIT(0);
202 /* set if a fatal kmemleak error has occurred */
203 static atomic_t kmemleak_error = ATOMIC_INIT(0);
204
205 /* minimum and maximum address that may be valid pointers */
206 static unsigned long min_addr = ULONG_MAX;
207 static unsigned long max_addr;
208
209 static struct task_struct *scan_thread;
210 /* used to avoid reporting of recently allocated objects */
211 static unsigned long jiffies_min_age;
212 static unsigned long jiffies_last_scan;
213 /* delay between automatic memory scannings */
214 static signed long jiffies_scan_wait;
215 /* enables or disables the task stacks scanning */
216 static int kmemleak_stack_scan = 1;
217 /* protects the memory scanning, parameters and debug/kmemleak file access */
218 static DEFINE_MUTEX(scan_mutex);
219 /* setting kmemleak=on, will set this var, skipping the disable */
220 static int kmemleak_skip_disable;
221
222
223 /*
224 * Early object allocation/freeing logging. Kmemleak is initialized after the
225 * kernel allocator. However, both the kernel allocator and kmemleak may
226 * allocate memory blocks which need to be tracked. Kmemleak defines an
227 * arbitrary buffer to hold the allocation/freeing information before it is
228 * fully initialized.
229 */
230
231 /* kmemleak operation type for early logging */
232 enum {
233 KMEMLEAK_ALLOC,
234 KMEMLEAK_ALLOC_PERCPU,
235 KMEMLEAK_FREE,
236 KMEMLEAK_FREE_PART,
237 KMEMLEAK_FREE_PERCPU,
238 KMEMLEAK_NOT_LEAK,
239 KMEMLEAK_IGNORE,
240 KMEMLEAK_SCAN_AREA,
241 KMEMLEAK_NO_SCAN
242 };
243
244 /*
245 * Structure holding the information passed to kmemleak callbacks during the
246 * early logging.
247 */
248 struct early_log {
249 int op_type; /* kmemleak operation type */
250 const void *ptr; /* allocated/freed memory block */
251 size_t size; /* memory block size */
252 int min_count; /* minimum reference count */
253 unsigned long trace[MAX_TRACE]; /* stack trace */
254 unsigned int trace_len; /* stack trace length */
255 };
256
257 /* early logging buffer and current position */
258 static struct early_log
259 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
260 static int crt_early_log __initdata;
261
262 static void kmemleak_disable(void);
263
264 /*
265 * Print a warning and dump the stack trace.
266 */
267 #define kmemleak_warn(x...) do { \
268 pr_warning(x); \
269 dump_stack(); \
270 atomic_set(&kmemleak_warning, 1); \
271 } while (0)
272
273 /*
274 * Macro invoked when a serious kmemleak condition occurred and cannot be
275 * recovered from. Kmemleak will be disabled and further allocation/freeing
276 * tracing no longer available.
277 */
278 #define kmemleak_stop(x...) do { \
279 kmemleak_warn(x); \
280 kmemleak_disable(); \
281 } while (0)
282
283 /*
284 * Printing of the objects hex dump to the seq file. The number of lines to be
285 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
286 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
287 * with the object->lock held.
288 */
289 static void hex_dump_object(struct seq_file *seq,
290 struct kmemleak_object *object)
291 {
292 const u8 *ptr = (const u8 *)object->pointer;
293 int i, len, remaining;
294 unsigned char linebuf[HEX_ROW_SIZE * 5];
295
296 /* limit the number of lines to HEX_MAX_LINES */
297 remaining = len =
298 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
299
300 seq_printf(seq, " hex dump (first %d bytes):\n", len);
301 for (i = 0; i < len; i += HEX_ROW_SIZE) {
302 int linelen = min(remaining, HEX_ROW_SIZE);
303
304 remaining -= HEX_ROW_SIZE;
305 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
306 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
307 HEX_ASCII);
308 seq_printf(seq, " %s\n", linebuf);
309 }
310 }
311
312 /*
313 * Object colors, encoded with count and min_count:
314 * - white - orphan object, not enough references to it (count < min_count)
315 * - gray - not orphan, not marked as false positive (min_count == 0) or
316 * sufficient references to it (count >= min_count)
317 * - black - ignore, it doesn't contain references (e.g. text section)
318 * (min_count == -1). No function defined for this color.
319 * Newly created objects don't have any color assigned (object->count == -1)
320 * before the next memory scan when they become white.
321 */
322 static bool color_white(const struct kmemleak_object *object)
323 {
324 return object->count != KMEMLEAK_BLACK &&
325 object->count < object->min_count;
326 }
327
328 static bool color_gray(const struct kmemleak_object *object)
329 {
330 return object->min_count != KMEMLEAK_BLACK &&
331 object->count >= object->min_count;
332 }
333
334 /*
335 * Objects are considered unreferenced only if their color is white, they have
336 * not be deleted and have a minimum age to avoid false positives caused by
337 * pointers temporarily stored in CPU registers.
338 */
339 static bool unreferenced_object(struct kmemleak_object *object)
340 {
341 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
342 time_before_eq(object->jiffies + jiffies_min_age,
343 jiffies_last_scan);
344 }
345
346 /*
347 * Printing of the unreferenced objects information to the seq file. The
348 * print_unreferenced function must be called with the object->lock held.
349 */
350 static void print_unreferenced(struct seq_file *seq,
351 struct kmemleak_object *object)
352 {
353 int i;
354 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
355
356 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
357 object->pointer, object->size);
358 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
359 object->comm, object->pid, object->jiffies,
360 msecs_age / 1000, msecs_age % 1000);
361 hex_dump_object(seq, object);
362 seq_printf(seq, " backtrace:\n");
363
364 for (i = 0; i < object->trace_len; i++) {
365 void *ptr = (void *)object->trace[i];
366 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
367 }
368 }
369
370 /*
371 * Print the kmemleak_object information. This function is used mainly for
372 * debugging special cases when kmemleak operations. It must be called with
373 * the object->lock held.
374 */
375 static void dump_object_info(struct kmemleak_object *object)
376 {
377 struct stack_trace trace;
378
379 trace.nr_entries = object->trace_len;
380 trace.entries = object->trace;
381
382 pr_notice("Object 0x%08lx (size %zu):\n",
383 object->tree_node.start, object->size);
384 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
385 object->comm, object->pid, object->jiffies);
386 pr_notice(" min_count = %d\n", object->min_count);
387 pr_notice(" count = %d\n", object->count);
388 pr_notice(" flags = 0x%lx\n", object->flags);
389 pr_notice(" checksum = %d\n", object->checksum);
390 pr_notice(" backtrace:\n");
391 print_stack_trace(&trace, 4);
392 }
393
394 /*
395 * Look-up a memory block metadata (kmemleak_object) in the priority search
396 * tree based on a pointer value. If alias is 0, only values pointing to the
397 * beginning of the memory block are allowed. The kmemleak_lock must be held
398 * when calling this function.
399 */
400 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
401 {
402 struct prio_tree_node *node;
403 struct prio_tree_iter iter;
404 struct kmemleak_object *object;
405
406 prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
407 node = prio_tree_next(&iter);
408 if (node) {
409 object = prio_tree_entry(node, struct kmemleak_object,
410 tree_node);
411 if (!alias && object->pointer != ptr) {
412 kmemleak_warn("Found object by alias at 0x%08lx\n",
413 ptr);
414 dump_object_info(object);
415 object = NULL;
416 }
417 } else
418 object = NULL;
419
420 return object;
421 }
422
423 /*
424 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
425 * that once an object's use_count reached 0, the RCU freeing was already
426 * registered and the object should no longer be used. This function must be
427 * called under the protection of rcu_read_lock().
428 */
429 static int get_object(struct kmemleak_object *object)
430 {
431 return atomic_inc_not_zero(&object->use_count);
432 }
433
434 /*
435 * RCU callback to free a kmemleak_object.
436 */
437 static void free_object_rcu(struct rcu_head *rcu)
438 {
439 struct hlist_node *elem, *tmp;
440 struct kmemleak_scan_area *area;
441 struct kmemleak_object *object =
442 container_of(rcu, struct kmemleak_object, rcu);
443
444 /*
445 * Once use_count is 0 (guaranteed by put_object), there is no other
446 * code accessing this object, hence no need for locking.
447 */
448 hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
449 hlist_del(elem);
450 kmem_cache_free(scan_area_cache, area);
451 }
452 kmem_cache_free(object_cache, object);
453 }
454
455 /*
456 * Decrement the object use_count. Once the count is 0, free the object using
457 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
458 * delete_object() path, the delayed RCU freeing ensures that there is no
459 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
460 * is also possible.
461 */
462 static void put_object(struct kmemleak_object *object)
463 {
464 if (!atomic_dec_and_test(&object->use_count))
465 return;
466
467 /* should only get here after delete_object was called */
468 WARN_ON(object->flags & OBJECT_ALLOCATED);
469
470 call_rcu(&object->rcu, free_object_rcu);
471 }
472
473 /*
474 * Look up an object in the prio search tree and increase its use_count.
475 */
476 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
477 {
478 unsigned long flags;
479 struct kmemleak_object *object = NULL;
480
481 rcu_read_lock();
482 read_lock_irqsave(&kmemleak_lock, flags);
483 if (ptr >= min_addr && ptr < max_addr)
484 object = lookup_object(ptr, alias);
485 read_unlock_irqrestore(&kmemleak_lock, flags);
486
487 /* check whether the object is still available */
488 if (object && !get_object(object))
489 object = NULL;
490 rcu_read_unlock();
491
492 return object;
493 }
494
495 /*
496 * Save stack trace to the given array of MAX_TRACE size.
497 */
498 static int __save_stack_trace(unsigned long *trace)
499 {
500 struct stack_trace stack_trace;
501
502 stack_trace.max_entries = MAX_TRACE;
503 stack_trace.nr_entries = 0;
504 stack_trace.entries = trace;
505 stack_trace.skip = 2;
506 save_stack_trace(&stack_trace);
507
508 return stack_trace.nr_entries;
509 }
510
511 /*
512 * Create the metadata (struct kmemleak_object) corresponding to an allocated
513 * memory block and add it to the object_list and object_tree_root.
514 */
515 static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
516 int min_count, gfp_t gfp)
517 {
518 unsigned long flags;
519 struct kmemleak_object *object;
520 struct prio_tree_node *node;
521
522 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
523 if (!object) {
524 pr_warning("Cannot allocate a kmemleak_object structure\n");
525 kmemleak_disable();
526 return NULL;
527 }
528
529 INIT_LIST_HEAD(&object->object_list);
530 INIT_LIST_HEAD(&object->gray_list);
531 INIT_HLIST_HEAD(&object->area_list);
532 spin_lock_init(&object->lock);
533 atomic_set(&object->use_count, 1);
534 object->flags = OBJECT_ALLOCATED;
535 object->pointer = ptr;
536 object->size = size;
537 object->min_count = min_count;
538 object->count = 0; /* white color initially */
539 object->jiffies = jiffies;
540 object->checksum = 0;
541
542 /* task information */
543 if (in_irq()) {
544 object->pid = 0;
545 strncpy(object->comm, "hardirq", sizeof(object->comm));
546 } else if (in_softirq()) {
547 object->pid = 0;
548 strncpy(object->comm, "softirq", sizeof(object->comm));
549 } else {
550 object->pid = current->pid;
551 /*
552 * There is a small chance of a race with set_task_comm(),
553 * however using get_task_comm() here may cause locking
554 * dependency issues with current->alloc_lock. In the worst
555 * case, the command line is not correct.
556 */
557 strncpy(object->comm, current->comm, sizeof(object->comm));
558 }
559
560 /* kernel backtrace */
561 object->trace_len = __save_stack_trace(object->trace);
562
563 INIT_PRIO_TREE_NODE(&object->tree_node);
564 object->tree_node.start = ptr;
565 object->tree_node.last = ptr + size - 1;
566
567 write_lock_irqsave(&kmemleak_lock, flags);
568
569 min_addr = min(min_addr, ptr);
570 max_addr = max(max_addr, ptr + size);
571 node = prio_tree_insert(&object_tree_root, &object->tree_node);
572 /*
573 * The code calling the kernel does not yet have the pointer to the
574 * memory block to be able to free it. However, we still hold the
575 * kmemleak_lock here in case parts of the kernel started freeing
576 * random memory blocks.
577 */
578 if (node != &object->tree_node) {
579 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
580 "(already existing)\n", ptr);
581 object = lookup_object(ptr, 1);
582 spin_lock(&object->lock);
583 dump_object_info(object);
584 spin_unlock(&object->lock);
585
586 goto out;
587 }
588 list_add_tail_rcu(&object->object_list, &object_list);
589 out:
590 write_unlock_irqrestore(&kmemleak_lock, flags);
591 return object;
592 }
593
594 /*
595 * Remove the metadata (struct kmemleak_object) for a memory block from the
596 * object_list and object_tree_root and decrement its use_count.
597 */
598 static void __delete_object(struct kmemleak_object *object)
599 {
600 unsigned long flags;
601
602 write_lock_irqsave(&kmemleak_lock, flags);
603 prio_tree_remove(&object_tree_root, &object->tree_node);
604 list_del_rcu(&object->object_list);
605 write_unlock_irqrestore(&kmemleak_lock, flags);
606
607 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
608 WARN_ON(atomic_read(&object->use_count) < 2);
609
610 /*
611 * Locking here also ensures that the corresponding memory block
612 * cannot be freed when it is being scanned.
613 */
614 spin_lock_irqsave(&object->lock, flags);
615 object->flags &= ~OBJECT_ALLOCATED;
616 spin_unlock_irqrestore(&object->lock, flags);
617 put_object(object);
618 }
619
620 /*
621 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
622 * delete it.
623 */
624 static void delete_object_full(unsigned long ptr)
625 {
626 struct kmemleak_object *object;
627
628 object = find_and_get_object(ptr, 0);
629 if (!object) {
630 #ifdef DEBUG
631 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
632 ptr);
633 #endif
634 return;
635 }
636 __delete_object(object);
637 put_object(object);
638 }
639
640 /*
641 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
642 * delete it. If the memory block is partially freed, the function may create
643 * additional metadata for the remaining parts of the block.
644 */
645 static void delete_object_part(unsigned long ptr, size_t size)
646 {
647 struct kmemleak_object *object;
648 unsigned long start, end;
649
650 object = find_and_get_object(ptr, 1);
651 if (!object) {
652 #ifdef DEBUG
653 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
654 "(size %zu)\n", ptr, size);
655 #endif
656 return;
657 }
658 __delete_object(object);
659
660 /*
661 * Create one or two objects that may result from the memory block
662 * split. Note that partial freeing is only done by free_bootmem() and
663 * this happens before kmemleak_init() is called. The path below is
664 * only executed during early log recording in kmemleak_init(), so
665 * GFP_KERNEL is enough.
666 */
667 start = object->pointer;
668 end = object->pointer + object->size;
669 if (ptr > start)
670 create_object(start, ptr - start, object->min_count,
671 GFP_KERNEL);
672 if (ptr + size < end)
673 create_object(ptr + size, end - ptr - size, object->min_count,
674 GFP_KERNEL);
675
676 put_object(object);
677 }
678
679 static void __paint_it(struct kmemleak_object *object, int color)
680 {
681 object->min_count = color;
682 if (color == KMEMLEAK_BLACK)
683 object->flags |= OBJECT_NO_SCAN;
684 }
685
686 static void paint_it(struct kmemleak_object *object, int color)
687 {
688 unsigned long flags;
689
690 spin_lock_irqsave(&object->lock, flags);
691 __paint_it(object, color);
692 spin_unlock_irqrestore(&object->lock, flags);
693 }
694
695 static void paint_ptr(unsigned long ptr, int color)
696 {
697 struct kmemleak_object *object;
698
699 object = find_and_get_object(ptr, 0);
700 if (!object) {
701 kmemleak_warn("Trying to color unknown object "
702 "at 0x%08lx as %s\n", ptr,
703 (color == KMEMLEAK_GREY) ? "Grey" :
704 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
705 return;
706 }
707 paint_it(object, color);
708 put_object(object);
709 }
710
711 /*
712 * Mark an object permanently as gray-colored so that it can no longer be
713 * reported as a leak. This is used in general to mark a false positive.
714 */
715 static void make_gray_object(unsigned long ptr)
716 {
717 paint_ptr(ptr, KMEMLEAK_GREY);
718 }
719
720 /*
721 * Mark the object as black-colored so that it is ignored from scans and
722 * reporting.
723 */
724 static void make_black_object(unsigned long ptr)
725 {
726 paint_ptr(ptr, KMEMLEAK_BLACK);
727 }
728
729 /*
730 * Add a scanning area to the object. If at least one such area is added,
731 * kmemleak will only scan these ranges rather than the whole memory block.
732 */
733 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
734 {
735 unsigned long flags;
736 struct kmemleak_object *object;
737 struct kmemleak_scan_area *area;
738
739 object = find_and_get_object(ptr, 1);
740 if (!object) {
741 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
742 ptr);
743 return;
744 }
745
746 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
747 if (!area) {
748 pr_warning("Cannot allocate a scan area\n");
749 goto out;
750 }
751
752 spin_lock_irqsave(&object->lock, flags);
753 if (ptr + size > object->pointer + object->size) {
754 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
755 dump_object_info(object);
756 kmem_cache_free(scan_area_cache, area);
757 goto out_unlock;
758 }
759
760 INIT_HLIST_NODE(&area->node);
761 area->start = ptr;
762 area->size = size;
763
764 hlist_add_head(&area->node, &object->area_list);
765 out_unlock:
766 spin_unlock_irqrestore(&object->lock, flags);
767 out:
768 put_object(object);
769 }
770
771 /*
772 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
773 * pointer. Such object will not be scanned by kmemleak but references to it
774 * are searched.
775 */
776 static void object_no_scan(unsigned long ptr)
777 {
778 unsigned long flags;
779 struct kmemleak_object *object;
780
781 object = find_and_get_object(ptr, 0);
782 if (!object) {
783 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
784 return;
785 }
786
787 spin_lock_irqsave(&object->lock, flags);
788 object->flags |= OBJECT_NO_SCAN;
789 spin_unlock_irqrestore(&object->lock, flags);
790 put_object(object);
791 }
792
793 /*
794 * Log an early kmemleak_* call to the early_log buffer. These calls will be
795 * processed later once kmemleak is fully initialized.
796 */
797 static void __init log_early(int op_type, const void *ptr, size_t size,
798 int min_count)
799 {
800 unsigned long flags;
801 struct early_log *log;
802
803 if (atomic_read(&kmemleak_error)) {
804 /* kmemleak stopped recording, just count the requests */
805 crt_early_log++;
806 return;
807 }
808
809 if (crt_early_log >= ARRAY_SIZE(early_log)) {
810 kmemleak_disable();
811 return;
812 }
813
814 /*
815 * There is no need for locking since the kernel is still in UP mode
816 * at this stage. Disabling the IRQs is enough.
817 */
818 local_irq_save(flags);
819 log = &early_log[crt_early_log];
820 log->op_type = op_type;
821 log->ptr = ptr;
822 log->size = size;
823 log->min_count = min_count;
824 log->trace_len = __save_stack_trace(log->trace);
825 crt_early_log++;
826 local_irq_restore(flags);
827 }
828
829 /*
830 * Log an early allocated block and populate the stack trace.
831 */
832 static void early_alloc(struct early_log *log)
833 {
834 struct kmemleak_object *object;
835 unsigned long flags;
836 int i;
837
838 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
839 return;
840
841 /*
842 * RCU locking needed to ensure object is not freed via put_object().
843 */
844 rcu_read_lock();
845 object = create_object((unsigned long)log->ptr, log->size,
846 log->min_count, GFP_ATOMIC);
847 if (!object)
848 goto out;
849 spin_lock_irqsave(&object->lock, flags);
850 for (i = 0; i < log->trace_len; i++)
851 object->trace[i] = log->trace[i];
852 object->trace_len = log->trace_len;
853 spin_unlock_irqrestore(&object->lock, flags);
854 out:
855 rcu_read_unlock();
856 }
857
858 /*
859 * Log an early allocated block and populate the stack trace.
860 */
861 static void early_alloc_percpu(struct early_log *log)
862 {
863 unsigned int cpu;
864 const void __percpu *ptr = log->ptr;
865
866 for_each_possible_cpu(cpu) {
867 log->ptr = per_cpu_ptr(ptr, cpu);
868 early_alloc(log);
869 }
870 }
871
872 /**
873 * kmemleak_alloc - register a newly allocated object
874 * @ptr: pointer to beginning of the object
875 * @size: size of the object
876 * @min_count: minimum number of references to this object. If during memory
877 * scanning a number of references less than @min_count is found,
878 * the object is reported as a memory leak. If @min_count is 0,
879 * the object is never reported as a leak. If @min_count is -1,
880 * the object is ignored (not scanned and not reported as a leak)
881 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
882 *
883 * This function is called from the kernel allocators when a new object
884 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
885 */
886 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
887 gfp_t gfp)
888 {
889 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
890
891 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
892 create_object((unsigned long)ptr, size, min_count, gfp);
893 else if (atomic_read(&kmemleak_early_log))
894 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
895 }
896 EXPORT_SYMBOL_GPL(kmemleak_alloc);
897
898 /**
899 * kmemleak_alloc_percpu - register a newly allocated __percpu object
900 * @ptr: __percpu pointer to beginning of the object
901 * @size: size of the object
902 *
903 * This function is called from the kernel percpu allocator when a new object
904 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
905 * allocation.
906 */
907 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
908 {
909 unsigned int cpu;
910
911 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
912
913 /*
914 * Percpu allocations are only scanned and not reported as leaks
915 * (min_count is set to 0).
916 */
917 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
918 for_each_possible_cpu(cpu)
919 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
920 size, 0, GFP_KERNEL);
921 else if (atomic_read(&kmemleak_early_log))
922 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
923 }
924 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
925
926 /**
927 * kmemleak_free - unregister a previously registered object
928 * @ptr: pointer to beginning of the object
929 *
930 * This function is called from the kernel allocators when an object (memory
931 * block) is freed (kmem_cache_free, kfree, vfree etc.).
932 */
933 void __ref kmemleak_free(const void *ptr)
934 {
935 pr_debug("%s(0x%p)\n", __func__, ptr);
936
937 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
938 delete_object_full((unsigned long)ptr);
939 else if (atomic_read(&kmemleak_early_log))
940 log_early(KMEMLEAK_FREE, ptr, 0, 0);
941 }
942 EXPORT_SYMBOL_GPL(kmemleak_free);
943
944 /**
945 * kmemleak_free_part - partially unregister a previously registered object
946 * @ptr: pointer to the beginning or inside the object. This also
947 * represents the start of the range to be freed
948 * @size: size to be unregistered
949 *
950 * This function is called when only a part of a memory block is freed
951 * (usually from the bootmem allocator).
952 */
953 void __ref kmemleak_free_part(const void *ptr, size_t size)
954 {
955 pr_debug("%s(0x%p)\n", __func__, ptr);
956
957 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
958 delete_object_part((unsigned long)ptr, size);
959 else if (atomic_read(&kmemleak_early_log))
960 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
961 }
962 EXPORT_SYMBOL_GPL(kmemleak_free_part);
963
964 /**
965 * kmemleak_free_percpu - unregister a previously registered __percpu object
966 * @ptr: __percpu pointer to beginning of the object
967 *
968 * This function is called from the kernel percpu allocator when an object
969 * (memory block) is freed (free_percpu).
970 */
971 void __ref kmemleak_free_percpu(const void __percpu *ptr)
972 {
973 unsigned int cpu;
974
975 pr_debug("%s(0x%p)\n", __func__, ptr);
976
977 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
978 for_each_possible_cpu(cpu)
979 delete_object_full((unsigned long)per_cpu_ptr(ptr,
980 cpu));
981 else if (atomic_read(&kmemleak_early_log))
982 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
983 }
984 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
985
986 /**
987 * kmemleak_not_leak - mark an allocated object as false positive
988 * @ptr: pointer to beginning of the object
989 *
990 * Calling this function on an object will cause the memory block to no longer
991 * be reported as leak and always be scanned.
992 */
993 void __ref kmemleak_not_leak(const void *ptr)
994 {
995 pr_debug("%s(0x%p)\n", __func__, ptr);
996
997 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
998 make_gray_object((unsigned long)ptr);
999 else if (atomic_read(&kmemleak_early_log))
1000 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
1001 }
1002 EXPORT_SYMBOL(kmemleak_not_leak);
1003
1004 /**
1005 * kmemleak_ignore - ignore an allocated object
1006 * @ptr: pointer to beginning of the object
1007 *
1008 * Calling this function on an object will cause the memory block to be
1009 * ignored (not scanned and not reported as a leak). This is usually done when
1010 * it is known that the corresponding block is not a leak and does not contain
1011 * any references to other allocated memory blocks.
1012 */
1013 void __ref kmemleak_ignore(const void *ptr)
1014 {
1015 pr_debug("%s(0x%p)\n", __func__, ptr);
1016
1017 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1018 make_black_object((unsigned long)ptr);
1019 else if (atomic_read(&kmemleak_early_log))
1020 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
1021 }
1022 EXPORT_SYMBOL(kmemleak_ignore);
1023
1024 /**
1025 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1026 * @ptr: pointer to beginning or inside the object. This also
1027 * represents the start of the scan area
1028 * @size: size of the scan area
1029 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1030 *
1031 * This function is used when it is known that only certain parts of an object
1032 * contain references to other objects. Kmemleak will only scan these areas
1033 * reducing the number false negatives.
1034 */
1035 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1036 {
1037 pr_debug("%s(0x%p)\n", __func__, ptr);
1038
1039 if (atomic_read(&kmemleak_enabled) && ptr && size && !IS_ERR(ptr))
1040 add_scan_area((unsigned long)ptr, size, gfp);
1041 else if (atomic_read(&kmemleak_early_log))
1042 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
1043 }
1044 EXPORT_SYMBOL(kmemleak_scan_area);
1045
1046 /**
1047 * kmemleak_no_scan - do not scan an allocated object
1048 * @ptr: pointer to beginning of the object
1049 *
1050 * This function notifies kmemleak not to scan the given memory block. Useful
1051 * in situations where it is known that the given object does not contain any
1052 * references to other objects. Kmemleak will not scan such objects reducing
1053 * the number of false negatives.
1054 */
1055 void __ref kmemleak_no_scan(const void *ptr)
1056 {
1057 pr_debug("%s(0x%p)\n", __func__, ptr);
1058
1059 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1060 object_no_scan((unsigned long)ptr);
1061 else if (atomic_read(&kmemleak_early_log))
1062 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
1063 }
1064 EXPORT_SYMBOL(kmemleak_no_scan);
1065
1066 /*
1067 * Update an object's checksum and return true if it was modified.
1068 */
1069 static bool update_checksum(struct kmemleak_object *object)
1070 {
1071 u32 old_csum = object->checksum;
1072
1073 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1074 return false;
1075
1076 object->checksum = crc32(0, (void *)object->pointer, object->size);
1077 return object->checksum != old_csum;
1078 }
1079
1080 /*
1081 * Memory scanning is a long process and it needs to be interruptable. This
1082 * function checks whether such interrupt condition occurred.
1083 */
1084 static int scan_should_stop(void)
1085 {
1086 if (!atomic_read(&kmemleak_enabled))
1087 return 1;
1088
1089 /*
1090 * This function may be called from either process or kthread context,
1091 * hence the need to check for both stop conditions.
1092 */
1093 if (current->mm)
1094 return signal_pending(current);
1095 else
1096 return kthread_should_stop();
1097
1098 return 0;
1099 }
1100
1101 /*
1102 * Scan a memory block (exclusive range) for valid pointers and add those
1103 * found to the gray list.
1104 */
1105 static void scan_block(void *_start, void *_end,
1106 struct kmemleak_object *scanned, int allow_resched)
1107 {
1108 unsigned long *ptr;
1109 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1110 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1111
1112 for (ptr = start; ptr < end; ptr++) {
1113 struct kmemleak_object *object;
1114 unsigned long flags;
1115 unsigned long pointer;
1116
1117 if (allow_resched)
1118 cond_resched();
1119 if (scan_should_stop())
1120 break;
1121
1122 /* don't scan uninitialized memory */
1123 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1124 BYTES_PER_POINTER))
1125 continue;
1126
1127 pointer = *ptr;
1128
1129 object = find_and_get_object(pointer, 1);
1130 if (!object)
1131 continue;
1132 if (object == scanned) {
1133 /* self referenced, ignore */
1134 put_object(object);
1135 continue;
1136 }
1137
1138 /*
1139 * Avoid the lockdep recursive warning on object->lock being
1140 * previously acquired in scan_object(). These locks are
1141 * enclosed by scan_mutex.
1142 */
1143 spin_lock_irqsave_nested(&object->lock, flags,
1144 SINGLE_DEPTH_NESTING);
1145 if (!color_white(object)) {
1146 /* non-orphan, ignored or new */
1147 spin_unlock_irqrestore(&object->lock, flags);
1148 put_object(object);
1149 continue;
1150 }
1151
1152 /*
1153 * Increase the object's reference count (number of pointers
1154 * to the memory block). If this count reaches the required
1155 * minimum, the object's color will become gray and it will be
1156 * added to the gray_list.
1157 */
1158 object->count++;
1159 if (color_gray(object)) {
1160 list_add_tail(&object->gray_list, &gray_list);
1161 spin_unlock_irqrestore(&object->lock, flags);
1162 continue;
1163 }
1164
1165 spin_unlock_irqrestore(&object->lock, flags);
1166 put_object(object);
1167 }
1168 }
1169
1170 /*
1171 * Scan a memory block corresponding to a kmemleak_object. A condition is
1172 * that object->use_count >= 1.
1173 */
1174 static void scan_object(struct kmemleak_object *object)
1175 {
1176 struct kmemleak_scan_area *area;
1177 struct hlist_node *elem;
1178 unsigned long flags;
1179
1180 /*
1181 * Once the object->lock is acquired, the corresponding memory block
1182 * cannot be freed (the same lock is acquired in delete_object).
1183 */
1184 spin_lock_irqsave(&object->lock, flags);
1185 if (object->flags & OBJECT_NO_SCAN)
1186 goto out;
1187 if (!(object->flags & OBJECT_ALLOCATED))
1188 /* already freed object */
1189 goto out;
1190 if (hlist_empty(&object->area_list)) {
1191 void *start = (void *)object->pointer;
1192 void *end = (void *)(object->pointer + object->size);
1193
1194 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1195 !(object->flags & OBJECT_NO_SCAN)) {
1196 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1197 object, 0);
1198 start += MAX_SCAN_SIZE;
1199
1200 spin_unlock_irqrestore(&object->lock, flags);
1201 cond_resched();
1202 spin_lock_irqsave(&object->lock, flags);
1203 }
1204 } else
1205 hlist_for_each_entry(area, elem, &object->area_list, node)
1206 scan_block((void *)area->start,
1207 (void *)(area->start + area->size),
1208 object, 0);
1209 out:
1210 spin_unlock_irqrestore(&object->lock, flags);
1211 }
1212
1213 /*
1214 * Scan the objects already referenced (gray objects). More objects will be
1215 * referenced and, if there are no memory leaks, all the objects are scanned.
1216 */
1217 static void scan_gray_list(void)
1218 {
1219 struct kmemleak_object *object, *tmp;
1220
1221 /*
1222 * The list traversal is safe for both tail additions and removals
1223 * from inside the loop. The kmemleak objects cannot be freed from
1224 * outside the loop because their use_count was incremented.
1225 */
1226 object = list_entry(gray_list.next, typeof(*object), gray_list);
1227 while (&object->gray_list != &gray_list) {
1228 cond_resched();
1229
1230 /* may add new objects to the list */
1231 if (!scan_should_stop())
1232 scan_object(object);
1233
1234 tmp = list_entry(object->gray_list.next, typeof(*object),
1235 gray_list);
1236
1237 /* remove the object from the list and release it */
1238 list_del(&object->gray_list);
1239 put_object(object);
1240
1241 object = tmp;
1242 }
1243 WARN_ON(!list_empty(&gray_list));
1244 }
1245
1246 /*
1247 * Scan data sections and all the referenced memory blocks allocated via the
1248 * kernel's standard allocators. This function must be called with the
1249 * scan_mutex held.
1250 */
1251 static void kmemleak_scan(void)
1252 {
1253 unsigned long flags;
1254 struct kmemleak_object *object;
1255 int i;
1256 int new_leaks = 0;
1257
1258 jiffies_last_scan = jiffies;
1259
1260 /* prepare the kmemleak_object's */
1261 rcu_read_lock();
1262 list_for_each_entry_rcu(object, &object_list, object_list) {
1263 spin_lock_irqsave(&object->lock, flags);
1264 #ifdef DEBUG
1265 /*
1266 * With a few exceptions there should be a maximum of
1267 * 1 reference to any object at this point.
1268 */
1269 if (atomic_read(&object->use_count) > 1) {
1270 pr_debug("object->use_count = %d\n",
1271 atomic_read(&object->use_count));
1272 dump_object_info(object);
1273 }
1274 #endif
1275 /* reset the reference count (whiten the object) */
1276 object->count = 0;
1277 if (color_gray(object) && get_object(object))
1278 list_add_tail(&object->gray_list, &gray_list);
1279
1280 spin_unlock_irqrestore(&object->lock, flags);
1281 }
1282 rcu_read_unlock();
1283
1284 /* data/bss scanning */
1285 scan_block(_sdata, _edata, NULL, 1);
1286 scan_block(__bss_start, __bss_stop, NULL, 1);
1287
1288 #ifdef CONFIG_SMP
1289 /* per-cpu sections scanning */
1290 for_each_possible_cpu(i)
1291 scan_block(__per_cpu_start + per_cpu_offset(i),
1292 __per_cpu_end + per_cpu_offset(i), NULL, 1);
1293 #endif
1294
1295 /*
1296 * Struct page scanning for each node.
1297 */
1298 lock_memory_hotplug();
1299 for_each_online_node(i) {
1300 pg_data_t *pgdat = NODE_DATA(i);
1301 unsigned long start_pfn = pgdat->node_start_pfn;
1302 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1303 unsigned long pfn;
1304
1305 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1306 struct page *page;
1307
1308 if (!pfn_valid(pfn))
1309 continue;
1310 page = pfn_to_page(pfn);
1311 /* only scan if page is in use */
1312 if (page_count(page) == 0)
1313 continue;
1314 scan_block(page, page + 1, NULL, 1);
1315 }
1316 }
1317 unlock_memory_hotplug();
1318
1319 /*
1320 * Scanning the task stacks (may introduce false negatives).
1321 */
1322 if (kmemleak_stack_scan) {
1323 struct task_struct *p, *g;
1324
1325 read_lock(&tasklist_lock);
1326 do_each_thread(g, p) {
1327 scan_block(task_stack_page(p), task_stack_page(p) +
1328 THREAD_SIZE, NULL, 0);
1329 } while_each_thread(g, p);
1330 read_unlock(&tasklist_lock);
1331 }
1332
1333 /*
1334 * Scan the objects already referenced from the sections scanned
1335 * above.
1336 */
1337 scan_gray_list();
1338
1339 /*
1340 * Check for new or unreferenced objects modified since the previous
1341 * scan and color them gray until the next scan.
1342 */
1343 rcu_read_lock();
1344 list_for_each_entry_rcu(object, &object_list, object_list) {
1345 spin_lock_irqsave(&object->lock, flags);
1346 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1347 && update_checksum(object) && get_object(object)) {
1348 /* color it gray temporarily */
1349 object->count = object->min_count;
1350 list_add_tail(&object->gray_list, &gray_list);
1351 }
1352 spin_unlock_irqrestore(&object->lock, flags);
1353 }
1354 rcu_read_unlock();
1355
1356 /*
1357 * Re-scan the gray list for modified unreferenced objects.
1358 */
1359 scan_gray_list();
1360
1361 /*
1362 * If scanning was stopped do not report any new unreferenced objects.
1363 */
1364 if (scan_should_stop())
1365 return;
1366
1367 /*
1368 * Scanning result reporting.
1369 */
1370 rcu_read_lock();
1371 list_for_each_entry_rcu(object, &object_list, object_list) {
1372 spin_lock_irqsave(&object->lock, flags);
1373 if (unreferenced_object(object) &&
1374 !(object->flags & OBJECT_REPORTED)) {
1375 object->flags |= OBJECT_REPORTED;
1376 new_leaks++;
1377 }
1378 spin_unlock_irqrestore(&object->lock, flags);
1379 }
1380 rcu_read_unlock();
1381
1382 if (new_leaks)
1383 pr_info("%d new suspected memory leaks (see "
1384 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1385
1386 }
1387
1388 /*
1389 * Thread function performing automatic memory scanning. Unreferenced objects
1390 * at the end of a memory scan are reported but only the first time.
1391 */
1392 static int kmemleak_scan_thread(void *arg)
1393 {
1394 static int first_run = 1;
1395
1396 pr_info("Automatic memory scanning thread started\n");
1397 set_user_nice(current, 10);
1398
1399 /*
1400 * Wait before the first scan to allow the system to fully initialize.
1401 */
1402 if (first_run) {
1403 first_run = 0;
1404 ssleep(SECS_FIRST_SCAN);
1405 }
1406
1407 while (!kthread_should_stop()) {
1408 signed long timeout = jiffies_scan_wait;
1409
1410 mutex_lock(&scan_mutex);
1411 kmemleak_scan();
1412 mutex_unlock(&scan_mutex);
1413
1414 /* wait before the next scan */
1415 while (timeout && !kthread_should_stop())
1416 timeout = schedule_timeout_interruptible(timeout);
1417 }
1418
1419 pr_info("Automatic memory scanning thread ended\n");
1420
1421 return 0;
1422 }
1423
1424 /*
1425 * Start the automatic memory scanning thread. This function must be called
1426 * with the scan_mutex held.
1427 */
1428 static void start_scan_thread(void)
1429 {
1430 if (scan_thread)
1431 return;
1432 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1433 if (IS_ERR(scan_thread)) {
1434 pr_warning("Failed to create the scan thread\n");
1435 scan_thread = NULL;
1436 }
1437 }
1438
1439 /*
1440 * Stop the automatic memory scanning thread. This function must be called
1441 * with the scan_mutex held.
1442 */
1443 static void stop_scan_thread(void)
1444 {
1445 if (scan_thread) {
1446 kthread_stop(scan_thread);
1447 scan_thread = NULL;
1448 }
1449 }
1450
1451 /*
1452 * Iterate over the object_list and return the first valid object at or after
1453 * the required position with its use_count incremented. The function triggers
1454 * a memory scanning when the pos argument points to the first position.
1455 */
1456 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1457 {
1458 struct kmemleak_object *object;
1459 loff_t n = *pos;
1460 int err;
1461
1462 err = mutex_lock_interruptible(&scan_mutex);
1463 if (err < 0)
1464 return ERR_PTR(err);
1465
1466 rcu_read_lock();
1467 list_for_each_entry_rcu(object, &object_list, object_list) {
1468 if (n-- > 0)
1469 continue;
1470 if (get_object(object))
1471 goto out;
1472 }
1473 object = NULL;
1474 out:
1475 return object;
1476 }
1477
1478 /*
1479 * Return the next object in the object_list. The function decrements the
1480 * use_count of the previous object and increases that of the next one.
1481 */
1482 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1483 {
1484 struct kmemleak_object *prev_obj = v;
1485 struct kmemleak_object *next_obj = NULL;
1486 struct list_head *n = &prev_obj->object_list;
1487
1488 ++(*pos);
1489
1490 list_for_each_continue_rcu(n, &object_list) {
1491 struct kmemleak_object *obj =
1492 list_entry(n, struct kmemleak_object, object_list);
1493 if (get_object(obj)) {
1494 next_obj = obj;
1495 break;
1496 }
1497 }
1498
1499 put_object(prev_obj);
1500 return next_obj;
1501 }
1502
1503 /*
1504 * Decrement the use_count of the last object required, if any.
1505 */
1506 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1507 {
1508 if (!IS_ERR(v)) {
1509 /*
1510 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1511 * waiting was interrupted, so only release it if !IS_ERR.
1512 */
1513 rcu_read_unlock();
1514 mutex_unlock(&scan_mutex);
1515 if (v)
1516 put_object(v);
1517 }
1518 }
1519
1520 /*
1521 * Print the information for an unreferenced object to the seq file.
1522 */
1523 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1524 {
1525 struct kmemleak_object *object = v;
1526 unsigned long flags;
1527
1528 spin_lock_irqsave(&object->lock, flags);
1529 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1530 print_unreferenced(seq, object);
1531 spin_unlock_irqrestore(&object->lock, flags);
1532 return 0;
1533 }
1534
1535 static const struct seq_operations kmemleak_seq_ops = {
1536 .start = kmemleak_seq_start,
1537 .next = kmemleak_seq_next,
1538 .stop = kmemleak_seq_stop,
1539 .show = kmemleak_seq_show,
1540 };
1541
1542 static int kmemleak_open(struct inode *inode, struct file *file)
1543 {
1544 return seq_open(file, &kmemleak_seq_ops);
1545 }
1546
1547 static int kmemleak_release(struct inode *inode, struct file *file)
1548 {
1549 return seq_release(inode, file);
1550 }
1551
1552 static int dump_str_object_info(const char *str)
1553 {
1554 unsigned long flags;
1555 struct kmemleak_object *object;
1556 unsigned long addr;
1557
1558 addr= simple_strtoul(str, NULL, 0);
1559 object = find_and_get_object(addr, 0);
1560 if (!object) {
1561 pr_info("Unknown object at 0x%08lx\n", addr);
1562 return -EINVAL;
1563 }
1564
1565 spin_lock_irqsave(&object->lock, flags);
1566 dump_object_info(object);
1567 spin_unlock_irqrestore(&object->lock, flags);
1568
1569 put_object(object);
1570 return 0;
1571 }
1572
1573 /*
1574 * We use grey instead of black to ensure we can do future scans on the same
1575 * objects. If we did not do future scans these black objects could
1576 * potentially contain references to newly allocated objects in the future and
1577 * we'd end up with false positives.
1578 */
1579 static void kmemleak_clear(void)
1580 {
1581 struct kmemleak_object *object;
1582 unsigned long flags;
1583
1584 rcu_read_lock();
1585 list_for_each_entry_rcu(object, &object_list, object_list) {
1586 spin_lock_irqsave(&object->lock, flags);
1587 if ((object->flags & OBJECT_REPORTED) &&
1588 unreferenced_object(object))
1589 __paint_it(object, KMEMLEAK_GREY);
1590 spin_unlock_irqrestore(&object->lock, flags);
1591 }
1592 rcu_read_unlock();
1593 }
1594
1595 /*
1596 * File write operation to configure kmemleak at run-time. The following
1597 * commands can be written to the /sys/kernel/debug/kmemleak file:
1598 * off - disable kmemleak (irreversible)
1599 * stack=on - enable the task stacks scanning
1600 * stack=off - disable the tasks stacks scanning
1601 * scan=on - start the automatic memory scanning thread
1602 * scan=off - stop the automatic memory scanning thread
1603 * scan=... - set the automatic memory scanning period in seconds (0 to
1604 * disable it)
1605 * scan - trigger a memory scan
1606 * clear - mark all current reported unreferenced kmemleak objects as
1607 * grey to ignore printing them
1608 * dump=... - dump information about the object found at the given address
1609 */
1610 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1611 size_t size, loff_t *ppos)
1612 {
1613 char buf[64];
1614 int buf_size;
1615 int ret;
1616
1617 if (!atomic_read(&kmemleak_enabled))
1618 return -EBUSY;
1619
1620 buf_size = min(size, (sizeof(buf) - 1));
1621 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1622 return -EFAULT;
1623 buf[buf_size] = 0;
1624
1625 ret = mutex_lock_interruptible(&scan_mutex);
1626 if (ret < 0)
1627 return ret;
1628
1629 if (strncmp(buf, "off", 3) == 0)
1630 kmemleak_disable();
1631 else if (strncmp(buf, "stack=on", 8) == 0)
1632 kmemleak_stack_scan = 1;
1633 else if (strncmp(buf, "stack=off", 9) == 0)
1634 kmemleak_stack_scan = 0;
1635 else if (strncmp(buf, "scan=on", 7) == 0)
1636 start_scan_thread();
1637 else if (strncmp(buf, "scan=off", 8) == 0)
1638 stop_scan_thread();
1639 else if (strncmp(buf, "scan=", 5) == 0) {
1640 unsigned long secs;
1641
1642 ret = strict_strtoul(buf + 5, 0, &secs);
1643 if (ret < 0)
1644 goto out;
1645 stop_scan_thread();
1646 if (secs) {
1647 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1648 start_scan_thread();
1649 }
1650 } else if (strncmp(buf, "scan", 4) == 0)
1651 kmemleak_scan();
1652 else if (strncmp(buf, "clear", 5) == 0)
1653 kmemleak_clear();
1654 else if (strncmp(buf, "dump=", 5) == 0)
1655 ret = dump_str_object_info(buf + 5);
1656 else
1657 ret = -EINVAL;
1658
1659 out:
1660 mutex_unlock(&scan_mutex);
1661 if (ret < 0)
1662 return ret;
1663
1664 /* ignore the rest of the buffer, only one command at a time */
1665 *ppos += size;
1666 return size;
1667 }
1668
1669 static const struct file_operations kmemleak_fops = {
1670 .owner = THIS_MODULE,
1671 .open = kmemleak_open,
1672 .read = seq_read,
1673 .write = kmemleak_write,
1674 .llseek = seq_lseek,
1675 .release = kmemleak_release,
1676 };
1677
1678 /*
1679 * Stop the memory scanning thread and free the kmemleak internal objects if
1680 * no previous scan thread (otherwise, kmemleak may still have some useful
1681 * information on memory leaks).
1682 */
1683 static void kmemleak_do_cleanup(struct work_struct *work)
1684 {
1685 struct kmemleak_object *object;
1686 bool cleanup = scan_thread == NULL;
1687
1688 mutex_lock(&scan_mutex);
1689 stop_scan_thread();
1690
1691 if (cleanup) {
1692 rcu_read_lock();
1693 list_for_each_entry_rcu(object, &object_list, object_list)
1694 delete_object_full(object->pointer);
1695 rcu_read_unlock();
1696 }
1697 mutex_unlock(&scan_mutex);
1698 }
1699
1700 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1701
1702 /*
1703 * Disable kmemleak. No memory allocation/freeing will be traced once this
1704 * function is called. Disabling kmemleak is an irreversible operation.
1705 */
1706 static void kmemleak_disable(void)
1707 {
1708 /* atomically check whether it was already invoked */
1709 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1710 return;
1711
1712 /* stop any memory operation tracing */
1713 atomic_set(&kmemleak_enabled, 0);
1714
1715 /* check whether it is too early for a kernel thread */
1716 if (atomic_read(&kmemleak_initialized))
1717 schedule_work(&cleanup_work);
1718
1719 pr_info("Kernel memory leak detector disabled\n");
1720 }
1721
1722 /*
1723 * Allow boot-time kmemleak disabling (enabled by default).
1724 */
1725 static int kmemleak_boot_config(char *str)
1726 {
1727 if (!str)
1728 return -EINVAL;
1729 if (strcmp(str, "off") == 0)
1730 kmemleak_disable();
1731 else if (strcmp(str, "on") == 0)
1732 kmemleak_skip_disable = 1;
1733 else
1734 return -EINVAL;
1735 return 0;
1736 }
1737 early_param("kmemleak", kmemleak_boot_config);
1738
1739 static void __init print_log_trace(struct early_log *log)
1740 {
1741 struct stack_trace trace;
1742
1743 trace.nr_entries = log->trace_len;
1744 trace.entries = log->trace;
1745
1746 pr_notice("Early log backtrace:\n");
1747 print_stack_trace(&trace, 2);
1748 }
1749
1750 /*
1751 * Kmemleak initialization.
1752 */
1753 void __init kmemleak_init(void)
1754 {
1755 int i;
1756 unsigned long flags;
1757
1758 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1759 if (!kmemleak_skip_disable) {
1760 atomic_set(&kmemleak_early_log, 0);
1761 kmemleak_disable();
1762 return;
1763 }
1764 #endif
1765
1766 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1767 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1768
1769 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1770 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1771 INIT_PRIO_TREE_ROOT(&object_tree_root);
1772
1773 if (crt_early_log >= ARRAY_SIZE(early_log))
1774 pr_warning("Early log buffer exceeded (%d), please increase "
1775 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1776
1777 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1778 local_irq_save(flags);
1779 atomic_set(&kmemleak_early_log, 0);
1780 if (atomic_read(&kmemleak_error)) {
1781 local_irq_restore(flags);
1782 return;
1783 } else
1784 atomic_set(&kmemleak_enabled, 1);
1785 local_irq_restore(flags);
1786
1787 /*
1788 * This is the point where tracking allocations is safe. Automatic
1789 * scanning is started during the late initcall. Add the early logged
1790 * callbacks to the kmemleak infrastructure.
1791 */
1792 for (i = 0; i < crt_early_log; i++) {
1793 struct early_log *log = &early_log[i];
1794
1795 switch (log->op_type) {
1796 case KMEMLEAK_ALLOC:
1797 early_alloc(log);
1798 break;
1799 case KMEMLEAK_ALLOC_PERCPU:
1800 early_alloc_percpu(log);
1801 break;
1802 case KMEMLEAK_FREE:
1803 kmemleak_free(log->ptr);
1804 break;
1805 case KMEMLEAK_FREE_PART:
1806 kmemleak_free_part(log->ptr, log->size);
1807 break;
1808 case KMEMLEAK_FREE_PERCPU:
1809 kmemleak_free_percpu(log->ptr);
1810 break;
1811 case KMEMLEAK_NOT_LEAK:
1812 kmemleak_not_leak(log->ptr);
1813 break;
1814 case KMEMLEAK_IGNORE:
1815 kmemleak_ignore(log->ptr);
1816 break;
1817 case KMEMLEAK_SCAN_AREA:
1818 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
1819 break;
1820 case KMEMLEAK_NO_SCAN:
1821 kmemleak_no_scan(log->ptr);
1822 break;
1823 default:
1824 kmemleak_warn("Unknown early log operation: %d\n",
1825 log->op_type);
1826 }
1827
1828 if (atomic_read(&kmemleak_warning)) {
1829 print_log_trace(log);
1830 atomic_set(&kmemleak_warning, 0);
1831 }
1832 }
1833 }
1834
1835 /*
1836 * Late initialization function.
1837 */
1838 static int __init kmemleak_late_init(void)
1839 {
1840 struct dentry *dentry;
1841
1842 atomic_set(&kmemleak_initialized, 1);
1843
1844 if (atomic_read(&kmemleak_error)) {
1845 /*
1846 * Some error occurred and kmemleak was disabled. There is a
1847 * small chance that kmemleak_disable() was called immediately
1848 * after setting kmemleak_initialized and we may end up with
1849 * two clean-up threads but serialized by scan_mutex.
1850 */
1851 schedule_work(&cleanup_work);
1852 return -ENOMEM;
1853 }
1854
1855 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1856 &kmemleak_fops);
1857 if (!dentry)
1858 pr_warning("Failed to create the debugfs kmemleak file\n");
1859 mutex_lock(&scan_mutex);
1860 start_scan_thread();
1861 mutex_unlock(&scan_mutex);
1862
1863 pr_info("Kernel memory leak detector initialized\n");
1864
1865 return 0;
1866 }
1867 late_initcall(kmemleak_late_init);