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 red black 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 * Locks and mutexes are acquired/nested in the following order:
  57 *
  58 *   scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING)
  59 *
  60 * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex
  61 * regions.
  62 *
  63 * The kmemleak_object structures have a use_count incremented or decremented
  64 * using the get_object()/put_object() functions. When the use_count becomes
  65 * 0, this count can no longer be incremented and put_object() schedules the
  66 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
  67 * function must be protected by rcu_read_lock() to avoid accessing a freed
  68 * structure.
  69 */
  70
  71#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  72
  73#include <linux/init.h>
  74#include <linux/kernel.h>
  75#include <linux/list.h>
  76#include <linux/sched.h>
  77#include <linux/jiffies.h>
  78#include <linux/delay.h>
  79#include <linux/export.h>
  80#include <linux/kthread.h>
  81#include <linux/rbtree.h>
  82#include <linux/fs.h>
  83#include <linux/debugfs.h>
  84#include <linux/seq_file.h>
  85#include <linux/cpumask.h>
  86#include <linux/spinlock.h>
  87#include <linux/mutex.h>
  88#include <linux/rcupdate.h>
  89#include <linux/stacktrace.h>
  90#include <linux/cache.h>
  91#include <linux/percpu.h>
  92#include <linux/hardirq.h>
  93#include <linux/mmzone.h>
  94#include <linux/slab.h>
  95#include <linux/thread_info.h>
  96#include <linux/err.h>
  97#include <linux/uaccess.h>
  98#include <linux/string.h>
  99#include <linux/nodemask.h>
 100#include <linux/mm.h>
 101#include <linux/workqueue.h>
 102#include <linux/crc32.h>
 103
 104#include <asm/sections.h>
 105#include <asm/processor.h>
 106#include <linux/atomic.h>
 107
 108#include <linux/kasan.h>
 109#include <linux/kmemcheck.h>
 110#include <linux/kmemleak.h>
 111#include <linux/memory_hotplug.h>
 112
 113/*
 114 * Kmemleak configuration and common defines.
 115 */
 116#define MAX_TRACE		16	/* stack trace length */
 117#define MSECS_MIN_AGE		5000	/* minimum object age for reporting */
 118#define SECS_FIRST_SCAN		60	/* delay before the first scan */
 119#define SECS_SCAN_WAIT		600	/* subsequent auto scanning delay */
 120#define MAX_SCAN_SIZE		4096	/* maximum size of a scanned block */
 121
 122#define BYTES_PER_POINTER	sizeof(void *)
 123
 124/* GFP bitmask for kmemleak internal allocations */
 125#define gfp_kmemleak_mask(gfp)	(((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
 126				 __GFP_NORETRY | __GFP_NOMEMALLOC | \
 127				 __GFP_NOWARN)
 128
 129/* scanning area inside a memory block */
 130struct kmemleak_scan_area {
 131	struct hlist_node node;
 132	unsigned long start;
 133	size_t size;
 134};
 135
 136#define KMEMLEAK_GREY	0
 137#define KMEMLEAK_BLACK	-1
 138
 139/*
 140 * Structure holding the metadata for each allocated memory block.
 141 * Modifications to such objects should be made while holding the
 142 * object->lock. Insertions or deletions from object_list, gray_list or
 143 * rb_node are already protected by the corresponding locks or mutex (see
 144 * the notes on locking above). These objects are reference-counted
 145 * (use_count) and freed using the RCU mechanism.
 146 */
 147struct kmemleak_object {
 148	spinlock_t lock;
 149	unsigned long flags;		/* object status flags */
 150	struct list_head object_list;
 151	struct list_head gray_list;
 152	struct rb_node rb_node;
 153	struct rcu_head rcu;		/* object_list lockless traversal */
 154	/* object usage count; object freed when use_count == 0 */
 155	atomic_t use_count;
 156	unsigned long pointer;
 157	size_t size;
 158	/* minimum number of a pointers found before it is considered leak */
 159	int min_count;
 160	/* the total number of pointers found pointing to this object */
 161	int count;
 162	/* checksum for detecting modified objects */
 163	u32 checksum;
 164	/* memory ranges to be scanned inside an object (empty for all) */
 165	struct hlist_head area_list;
 166	unsigned long trace[MAX_TRACE];
 167	unsigned int trace_len;
 168	unsigned long jiffies;		/* creation timestamp */
 169	pid_t pid;			/* pid of the current task */
 170	char comm[TASK_COMM_LEN];	/* executable name */
 171};
 172
 173/* flag representing the memory block allocation status */
 174#define OBJECT_ALLOCATED	(1 << 0)
 175/* flag set after the first reporting of an unreference object */
 176#define OBJECT_REPORTED		(1 << 1)
 177/* flag set to not scan the object */
 178#define OBJECT_NO_SCAN		(1 << 2)
 179
 180/* number of bytes to print per line; must be 16 or 32 */
 181#define HEX_ROW_SIZE		16
 182/* number of bytes to print at a time (1, 2, 4, 8) */
 183#define HEX_GROUP_SIZE		1
 184/* include ASCII after the hex output */
 185#define HEX_ASCII		1
 186/* max number of lines to be printed */
 187#define HEX_MAX_LINES		2
 188
 189/* the list of all allocated objects */
 190static LIST_HEAD(object_list);
 191/* the list of gray-colored objects (see color_gray comment below) */
 192static LIST_HEAD(gray_list);
 193/* search tree for object boundaries */
 194static struct rb_root object_tree_root = RB_ROOT;
 195/* rw_lock protecting the access to object_list and object_tree_root */
 196static DEFINE_RWLOCK(kmemleak_lock);
 197
 198/* allocation caches for kmemleak internal data */
 199static struct kmem_cache *object_cache;
 200static struct kmem_cache *scan_area_cache;
 201
 202/* set if tracing memory operations is enabled */
 203static int kmemleak_enabled;
 204/* same as above but only for the kmemleak_free() callback */
 205static int kmemleak_free_enabled;
 206/* set in the late_initcall if there were no errors */
 207static int kmemleak_initialized;
 208/* enables or disables early logging of the memory operations */
 209static int kmemleak_early_log = 1;
 210/* set if a kmemleak warning was issued */
 211static int kmemleak_warning;
 212/* set if a fatal kmemleak error has occurred */
 213static int kmemleak_error;
 214
 215/* minimum and maximum address that may be valid pointers */
 216static unsigned long min_addr = ULONG_MAX;
 217static unsigned long max_addr;
 218
 219static struct task_struct *scan_thread;
 220/* used to avoid reporting of recently allocated objects */
 221static unsigned long jiffies_min_age;
 222static unsigned long jiffies_last_scan;
 223/* delay between automatic memory scannings */
 224static signed long jiffies_scan_wait;
 225/* enables or disables the task stacks scanning */
 226static int kmemleak_stack_scan = 1;
 227/* protects the memory scanning, parameters and debug/kmemleak file access */
 228static DEFINE_MUTEX(scan_mutex);
 229/* setting kmemleak=on, will set this var, skipping the disable */
 230static int kmemleak_skip_disable;
 231/* If there are leaks that can be reported */
 232static bool kmemleak_found_leaks;
 233
 234/*
 235 * Early object allocation/freeing logging. Kmemleak is initialized after the
 236 * kernel allocator. However, both the kernel allocator and kmemleak may
 237 * allocate memory blocks which need to be tracked. Kmemleak defines an
 238 * arbitrary buffer to hold the allocation/freeing information before it is
 239 * fully initialized.
 240 */
 241
 242/* kmemleak operation type for early logging */
 243enum {
 244	KMEMLEAK_ALLOC,
 245	KMEMLEAK_ALLOC_PERCPU,
 246	KMEMLEAK_FREE,
 247	KMEMLEAK_FREE_PART,
 248	KMEMLEAK_FREE_PERCPU,
 249	KMEMLEAK_NOT_LEAK,
 250	KMEMLEAK_IGNORE,
 251	KMEMLEAK_SCAN_AREA,
 252	KMEMLEAK_NO_SCAN
 253};
 254
 255/*
 256 * Structure holding the information passed to kmemleak callbacks during the
 257 * early logging.
 258 */
 259struct early_log {
 260	int op_type;			/* kmemleak operation type */
 261	const void *ptr;		/* allocated/freed memory block */
 262	size_t size;			/* memory block size */
 263	int min_count;			/* minimum reference count */
 264	unsigned long trace[MAX_TRACE];	/* stack trace */
 265	unsigned int trace_len;		/* stack trace length */
 266};
 267
 268/* early logging buffer and current position */
 269static struct early_log
 270	early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
 271static int crt_early_log __initdata;
 272
 273static void kmemleak_disable(void);
 274
 275/*
 276 * Print a warning and dump the stack trace.
 277 */
 278#define kmemleak_warn(x...)	do {		\
 279	pr_warn(x);				\
 280	dump_stack();				\
 281	kmemleak_warning = 1;			\
 282} while (0)
 283
 284/*
 285 * Macro invoked when a serious kmemleak condition occurred and cannot be
 286 * recovered from. Kmemleak will be disabled and further allocation/freeing
 287 * tracing no longer available.
 288 */
 289#define kmemleak_stop(x...)	do {	\
 290	kmemleak_warn(x);		\
 291	kmemleak_disable();		\
 292} while (0)
 293
 294/*
 295 * Printing of the objects hex dump to the seq file. The number of lines to be
 296 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
 297 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
 298 * with the object->lock held.
 299 */
 300static void hex_dump_object(struct seq_file *seq,
 301			    struct kmemleak_object *object)
 302{
 303	const u8 *ptr = (const u8 *)object->pointer;
 304	size_t len;
 
 305
 306	/* limit the number of lines to HEX_MAX_LINES */
 307	len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
 
 308
 309	seq_printf(seq, "  hex dump (first %zu bytes):\n", len);
 310	seq_hex_dump(seq, "    ", DUMP_PREFIX_NONE, HEX_ROW_SIZE,
 311		     HEX_GROUP_SIZE, ptr, len, HEX_ASCII);
 
 
 
 
 
 
 
 312}
 313
 314/*
 315 * Object colors, encoded with count and min_count:
 316 * - white - orphan object, not enough references to it (count < min_count)
 317 * - gray  - not orphan, not marked as false positive (min_count == 0) or
 318 *		sufficient references to it (count >= min_count)
 319 * - black - ignore, it doesn't contain references (e.g. text section)
 320 *		(min_count == -1). No function defined for this color.
 321 * Newly created objects don't have any color assigned (object->count == -1)
 322 * before the next memory scan when they become white.
 323 */
 324static bool color_white(const struct kmemleak_object *object)
 325{
 326	return object->count != KMEMLEAK_BLACK &&
 327		object->count < object->min_count;
 328}
 329
 330static bool color_gray(const struct kmemleak_object *object)
 331{
 332	return object->min_count != KMEMLEAK_BLACK &&
 333		object->count >= object->min_count;
 334}
 335
 336/*
 337 * Objects are considered unreferenced only if their color is white, they have
 338 * not be deleted and have a minimum age to avoid false positives caused by
 339 * pointers temporarily stored in CPU registers.
 340 */
 341static bool unreferenced_object(struct kmemleak_object *object)
 342{
 343	return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
 344		time_before_eq(object->jiffies + jiffies_min_age,
 345			       jiffies_last_scan);
 346}
 347
 348/*
 349 * Printing of the unreferenced objects information to the seq file. The
 350 * print_unreferenced function must be called with the object->lock held.
 351 */
 352static void print_unreferenced(struct seq_file *seq,
 353			       struct kmemleak_object *object)
 354{
 355	int i;
 356	unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
 357
 358	seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
 359		   object->pointer, object->size);
 360	seq_printf(seq, "  comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
 361		   object->comm, object->pid, object->jiffies,
 362		   msecs_age / 1000, msecs_age % 1000);
 363	hex_dump_object(seq, object);
 364	seq_printf(seq, "  backtrace:\n");
 365
 366	for (i = 0; i < object->trace_len; i++) {
 367		void *ptr = (void *)object->trace[i];
 368		seq_printf(seq, "    [<%p>] %pS\n", ptr, ptr);
 369	}
 370}
 371
 372/*
 373 * Print the kmemleak_object information. This function is used mainly for
 374 * debugging special cases when kmemleak operations. It must be called with
 375 * the object->lock held.
 376 */
 377static void dump_object_info(struct kmemleak_object *object)
 378{
 379	struct stack_trace trace;
 380
 381	trace.nr_entries = object->trace_len;
 382	trace.entries = object->trace;
 383
 384	pr_notice("Object 0x%08lx (size %zu):\n",
 385		  object->pointer, object->size);
 386	pr_notice("  comm \"%s\", pid %d, jiffies %lu\n",
 387		  object->comm, object->pid, object->jiffies);
 388	pr_notice("  min_count = %d\n", object->min_count);
 389	pr_notice("  count = %d\n", object->count);
 390	pr_notice("  flags = 0x%lx\n", object->flags);
 391	pr_notice("  checksum = %u\n", object->checksum);
 392	pr_notice("  backtrace:\n");
 393	print_stack_trace(&trace, 4);
 394}
 395
 396/*
 397 * Look-up a memory block metadata (kmemleak_object) in the object search
 398 * tree based on a pointer value. If alias is 0, only values pointing to the
 399 * beginning of the memory block are allowed. The kmemleak_lock must be held
 400 * when calling this function.
 401 */
 402static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
 403{
 404	struct rb_node *rb = object_tree_root.rb_node;
 
 
 405
 406	while (rb) {
 407		struct kmemleak_object *object =
 408			rb_entry(rb, struct kmemleak_object, rb_node);
 409		if (ptr < object->pointer)
 410			rb = object->rb_node.rb_left;
 411		else if (object->pointer + object->size <= ptr)
 412			rb = object->rb_node.rb_right;
 413		else if (object->pointer == ptr || alias)
 414			return object;
 415		else {
 416			kmemleak_warn("Found object by alias at 0x%08lx\n",
 417				      ptr);
 418			dump_object_info(object);
 419			break;
 420		}
 421	}
 422	return NULL;
 
 
 423}
 424
 425/*
 426 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
 427 * that once an object's use_count reached 0, the RCU freeing was already
 428 * registered and the object should no longer be used. This function must be
 429 * called under the protection of rcu_read_lock().
 430 */
 431static int get_object(struct kmemleak_object *object)
 432{
 433	return atomic_inc_not_zero(&object->use_count);
 434}
 435
 436/*
 437 * RCU callback to free a kmemleak_object.
 438 */
 439static void free_object_rcu(struct rcu_head *rcu)
 440{
 441	struct hlist_node *tmp;
 442	struct kmemleak_scan_area *area;
 443	struct kmemleak_object *object =
 444		container_of(rcu, struct kmemleak_object, rcu);
 445
 446	/*
 447	 * Once use_count is 0 (guaranteed by put_object), there is no other
 448	 * code accessing this object, hence no need for locking.
 449	 */
 450	hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
 451		hlist_del(&area->node);
 452		kmem_cache_free(scan_area_cache, area);
 453	}
 454	kmem_cache_free(object_cache, object);
 455}
 456
 457/*
 458 * Decrement the object use_count. Once the count is 0, free the object using
 459 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
 460 * delete_object() path, the delayed RCU freeing ensures that there is no
 461 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
 462 * is also possible.
 463 */
 464static void put_object(struct kmemleak_object *object)
 465{
 466	if (!atomic_dec_and_test(&object->use_count))
 467		return;
 468
 469	/* should only get here after delete_object was called */
 470	WARN_ON(object->flags & OBJECT_ALLOCATED);
 471
 472	call_rcu(&object->rcu, free_object_rcu);
 473}
 474
 475/*
 476 * Look up an object in the object search tree and increase its use_count.
 477 */
 478static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
 479{
 480	unsigned long flags;
 481	struct kmemleak_object *object;
 482
 483	rcu_read_lock();
 484	read_lock_irqsave(&kmemleak_lock, flags);
 485	object = lookup_object(ptr, alias);
 
 486	read_unlock_irqrestore(&kmemleak_lock, flags);
 487
 488	/* check whether the object is still available */
 489	if (object && !get_object(object))
 490		object = NULL;
 491	rcu_read_unlock();
 492
 493	return object;
 494}
 495
 496/*
 497 * Look up an object in the object search tree and remove it from both
 498 * object_tree_root and object_list. The returned object's use_count should be
 499 * at least 1, as initially set by create_object().
 500 */
 501static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
 502{
 503	unsigned long flags;
 504	struct kmemleak_object *object;
 505
 506	write_lock_irqsave(&kmemleak_lock, flags);
 507	object = lookup_object(ptr, alias);
 508	if (object) {
 509		rb_erase(&object->rb_node, &object_tree_root);
 510		list_del_rcu(&object->object_list);
 511	}
 512	write_unlock_irqrestore(&kmemleak_lock, flags);
 513
 514	return object;
 515}
 516
 517/*
 518 * Save stack trace to the given array of MAX_TRACE size.
 519 */
 520static int __save_stack_trace(unsigned long *trace)
 521{
 522	struct stack_trace stack_trace;
 523
 524	stack_trace.max_entries = MAX_TRACE;
 525	stack_trace.nr_entries = 0;
 526	stack_trace.entries = trace;
 527	stack_trace.skip = 2;
 528	save_stack_trace(&stack_trace);
 529
 530	return stack_trace.nr_entries;
 531}
 532
 533/*
 534 * Create the metadata (struct kmemleak_object) corresponding to an allocated
 535 * memory block and add it to the object_list and object_tree_root.
 536 */
 537static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
 538					     int min_count, gfp_t gfp)
 539{
 540	unsigned long flags;
 541	struct kmemleak_object *object, *parent;
 542	struct rb_node **link, *rb_parent;
 543
 544	object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
 545	if (!object) {
 546		pr_warn("Cannot allocate a kmemleak_object structure\n");
 547		kmemleak_disable();
 548		return NULL;
 549	}
 550
 551	INIT_LIST_HEAD(&object->object_list);
 552	INIT_LIST_HEAD(&object->gray_list);
 553	INIT_HLIST_HEAD(&object->area_list);
 554	spin_lock_init(&object->lock);
 555	atomic_set(&object->use_count, 1);
 556	object->flags = OBJECT_ALLOCATED;
 557	object->pointer = ptr;
 558	object->size = size;
 559	object->min_count = min_count;
 560	object->count = 0;			/* white color initially */
 561	object->jiffies = jiffies;
 562	object->checksum = 0;
 563
 564	/* task information */
 565	if (in_irq()) {
 566		object->pid = 0;
 567		strncpy(object->comm, "hardirq", sizeof(object->comm));
 568	} else if (in_softirq()) {
 569		object->pid = 0;
 570		strncpy(object->comm, "softirq", sizeof(object->comm));
 571	} else {
 572		object->pid = current->pid;
 573		/*
 574		 * There is a small chance of a race with set_task_comm(),
 575		 * however using get_task_comm() here may cause locking
 576		 * dependency issues with current->alloc_lock. In the worst
 577		 * case, the command line is not correct.
 578		 */
 579		strncpy(object->comm, current->comm, sizeof(object->comm));
 580	}
 581
 582	/* kernel backtrace */
 583	object->trace_len = __save_stack_trace(object->trace);
 584
 
 
 
 
 585	write_lock_irqsave(&kmemleak_lock, flags);
 586
 587	min_addr = min(min_addr, ptr);
 588	max_addr = max(max_addr, ptr + size);
 589	link = &object_tree_root.rb_node;
 590	rb_parent = NULL;
 591	while (*link) {
 592		rb_parent = *link;
 593		parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
 594		if (ptr + size <= parent->pointer)
 595			link = &parent->rb_node.rb_left;
 596		else if (parent->pointer + parent->size <= ptr)
 597			link = &parent->rb_node.rb_right;
 598		else {
 599			kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
 600				      ptr);
 601			/*
 602			 * No need for parent->lock here since "parent" cannot
 603			 * be freed while the kmemleak_lock is held.
 604			 */
 605			dump_object_info(parent);
 606			kmem_cache_free(object_cache, object);
 607			object = NULL;
 608			goto out;
 609		}
 610	}
 611	rb_link_node(&object->rb_node, rb_parent, link);
 612	rb_insert_color(&object->rb_node, &object_tree_root);
 613
 
 
 614	list_add_tail_rcu(&object->object_list, &object_list);
 615out:
 616	write_unlock_irqrestore(&kmemleak_lock, flags);
 617	return object;
 618}
 619
 620/*
 621 * Mark the object as not allocated and schedule RCU freeing via put_object().
 
 622 */
 623static void __delete_object(struct kmemleak_object *object)
 624{
 625	unsigned long flags;
 626
 
 
 
 
 
 627	WARN_ON(!(object->flags & OBJECT_ALLOCATED));
 628	WARN_ON(atomic_read(&object->use_count) < 1);
 629
 630	/*
 631	 * Locking here also ensures that the corresponding memory block
 632	 * cannot be freed when it is being scanned.
 633	 */
 634	spin_lock_irqsave(&object->lock, flags);
 635	object->flags &= ~OBJECT_ALLOCATED;
 636	spin_unlock_irqrestore(&object->lock, flags);
 637	put_object(object);
 638}
 639
 640/*
 641 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
 642 * delete it.
 643 */
 644static void delete_object_full(unsigned long ptr)
 645{
 646	struct kmemleak_object *object;
 647
 648	object = find_and_remove_object(ptr, 0);
 649	if (!object) {
 650#ifdef DEBUG
 651		kmemleak_warn("Freeing unknown object at 0x%08lx\n",
 652			      ptr);
 653#endif
 654		return;
 655	}
 656	__delete_object(object);
 
 657}
 658
 659/*
 660 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
 661 * delete it. If the memory block is partially freed, the function may create
 662 * additional metadata for the remaining parts of the block.
 663 */
 664static void delete_object_part(unsigned long ptr, size_t size)
 665{
 666	struct kmemleak_object *object;
 667	unsigned long start, end;
 668
 669	object = find_and_remove_object(ptr, 1);
 670	if (!object) {
 671#ifdef DEBUG
 672		kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
 673			      ptr, size);
 674#endif
 675		return;
 676	}
 
 677
 678	/*
 679	 * Create one or two objects that may result from the memory block
 680	 * split. Note that partial freeing is only done by free_bootmem() and
 681	 * this happens before kmemleak_init() is called. The path below is
 682	 * only executed during early log recording in kmemleak_init(), so
 683	 * GFP_KERNEL is enough.
 684	 */
 685	start = object->pointer;
 686	end = object->pointer + object->size;
 687	if (ptr > start)
 688		create_object(start, ptr - start, object->min_count,
 689			      GFP_KERNEL);
 690	if (ptr + size < end)
 691		create_object(ptr + size, end - ptr - size, object->min_count,
 692			      GFP_KERNEL);
 693
 694	__delete_object(object);
 695}
 696
 697static void __paint_it(struct kmemleak_object *object, int color)
 698{
 699	object->min_count = color;
 700	if (color == KMEMLEAK_BLACK)
 701		object->flags |= OBJECT_NO_SCAN;
 702}
 703
 704static void paint_it(struct kmemleak_object *object, int color)
 705{
 706	unsigned long flags;
 707
 708	spin_lock_irqsave(&object->lock, flags);
 709	__paint_it(object, color);
 710	spin_unlock_irqrestore(&object->lock, flags);
 711}
 712
 713static void paint_ptr(unsigned long ptr, int color)
 714{
 715	struct kmemleak_object *object;
 716
 717	object = find_and_get_object(ptr, 0);
 718	if (!object) {
 719		kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
 720			      ptr,
 721			      (color == KMEMLEAK_GREY) ? "Grey" :
 722			      (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
 723		return;
 724	}
 725	paint_it(object, color);
 726	put_object(object);
 727}
 728
 729/*
 730 * Mark an object permanently as gray-colored so that it can no longer be
 731 * reported as a leak. This is used in general to mark a false positive.
 732 */
 733static void make_gray_object(unsigned long ptr)
 734{
 735	paint_ptr(ptr, KMEMLEAK_GREY);
 736}
 737
 738/*
 739 * Mark the object as black-colored so that it is ignored from scans and
 740 * reporting.
 741 */
 742static void make_black_object(unsigned long ptr)
 743{
 744	paint_ptr(ptr, KMEMLEAK_BLACK);
 745}
 746
 747/*
 748 * Add a scanning area to the object. If at least one such area is added,
 749 * kmemleak will only scan these ranges rather than the whole memory block.
 750 */
 751static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
 752{
 753	unsigned long flags;
 754	struct kmemleak_object *object;
 755	struct kmemleak_scan_area *area;
 756
 757	object = find_and_get_object(ptr, 1);
 758	if (!object) {
 759		kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
 760			      ptr);
 761		return;
 762	}
 763
 764	area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
 765	if (!area) {
 766		pr_warn("Cannot allocate a scan area\n");
 767		goto out;
 768	}
 769
 770	spin_lock_irqsave(&object->lock, flags);
 771	if (size == SIZE_MAX) {
 772		size = object->pointer + object->size - ptr;
 773	} else if (ptr + size > object->pointer + object->size) {
 774		kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
 775		dump_object_info(object);
 776		kmem_cache_free(scan_area_cache, area);
 777		goto out_unlock;
 778	}
 779
 780	INIT_HLIST_NODE(&area->node);
 781	area->start = ptr;
 782	area->size = size;
 783
 784	hlist_add_head(&area->node, &object->area_list);
 785out_unlock:
 786	spin_unlock_irqrestore(&object->lock, flags);
 787out:
 788	put_object(object);
 789}
 790
 791/*
 792 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
 793 * pointer. Such object will not be scanned by kmemleak but references to it
 794 * are searched.
 795 */
 796static void object_no_scan(unsigned long ptr)
 797{
 798	unsigned long flags;
 799	struct kmemleak_object *object;
 800
 801	object = find_and_get_object(ptr, 0);
 802	if (!object) {
 803		kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
 804		return;
 805	}
 806
 807	spin_lock_irqsave(&object->lock, flags);
 808	object->flags |= OBJECT_NO_SCAN;
 809	spin_unlock_irqrestore(&object->lock, flags);
 810	put_object(object);
 811}
 812
 813/*
 814 * Log an early kmemleak_* call to the early_log buffer. These calls will be
 815 * processed later once kmemleak is fully initialized.
 816 */
 817static void __init log_early(int op_type, const void *ptr, size_t size,
 818			     int min_count)
 819{
 820	unsigned long flags;
 821	struct early_log *log;
 822
 823	if (kmemleak_error) {
 824		/* kmemleak stopped recording, just count the requests */
 825		crt_early_log++;
 826		return;
 827	}
 828
 829	if (crt_early_log >= ARRAY_SIZE(early_log)) {
 830		crt_early_log++;
 831		kmemleak_disable();
 832		return;
 833	}
 834
 835	/*
 836	 * There is no need for locking since the kernel is still in UP mode
 837	 * at this stage. Disabling the IRQs is enough.
 838	 */
 839	local_irq_save(flags);
 840	log = &early_log[crt_early_log];
 841	log->op_type = op_type;
 842	log->ptr = ptr;
 843	log->size = size;
 844	log->min_count = min_count;
 845	log->trace_len = __save_stack_trace(log->trace);
 846	crt_early_log++;
 847	local_irq_restore(flags);
 848}
 849
 850/*
 851 * Log an early allocated block and populate the stack trace.
 852 */
 853static void early_alloc(struct early_log *log)
 854{
 855	struct kmemleak_object *object;
 856	unsigned long flags;
 857	int i;
 858
 859	if (!kmemleak_enabled || !log->ptr || IS_ERR(log->ptr))
 860		return;
 861
 862	/*
 863	 * RCU locking needed to ensure object is not freed via put_object().
 864	 */
 865	rcu_read_lock();
 866	object = create_object((unsigned long)log->ptr, log->size,
 867			       log->min_count, GFP_ATOMIC);
 868	if (!object)
 869		goto out;
 870	spin_lock_irqsave(&object->lock, flags);
 871	for (i = 0; i < log->trace_len; i++)
 872		object->trace[i] = log->trace[i];
 873	object->trace_len = log->trace_len;
 874	spin_unlock_irqrestore(&object->lock, flags);
 875out:
 876	rcu_read_unlock();
 877}
 878
 879/*
 880 * Log an early allocated block and populate the stack trace.
 881 */
 882static void early_alloc_percpu(struct early_log *log)
 883{
 884	unsigned int cpu;
 885	const void __percpu *ptr = log->ptr;
 886
 887	for_each_possible_cpu(cpu) {
 888		log->ptr = per_cpu_ptr(ptr, cpu);
 889		early_alloc(log);
 890	}
 891}
 892
 893/**
 894 * kmemleak_alloc - register a newly allocated object
 895 * @ptr:	pointer to beginning of the object
 896 * @size:	size of the object
 897 * @min_count:	minimum number of references to this object. If during memory
 898 *		scanning a number of references less than @min_count is found,
 899 *		the object is reported as a memory leak. If @min_count is 0,
 900 *		the object is never reported as a leak. If @min_count is -1,
 901 *		the object is ignored (not scanned and not reported as a leak)
 902 * @gfp:	kmalloc() flags used for kmemleak internal memory allocations
 903 *
 904 * This function is called from the kernel allocators when a new object
 905 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
 906 */
 907void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
 908			  gfp_t gfp)
 909{
 910	pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
 911
 912	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 913		create_object((unsigned long)ptr, size, min_count, gfp);
 914	else if (kmemleak_early_log)
 915		log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
 916}
 917EXPORT_SYMBOL_GPL(kmemleak_alloc);
 918
 919/**
 920 * kmemleak_alloc_percpu - register a newly allocated __percpu object
 921 * @ptr:	__percpu pointer to beginning of the object
 922 * @size:	size of the object
 923 * @gfp:	flags used for kmemleak internal memory allocations
 924 *
 925 * This function is called from the kernel percpu allocator when a new object
 926 * (memory block) is allocated (alloc_percpu).
 
 927 */
 928void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
 929				 gfp_t gfp)
 930{
 931	unsigned int cpu;
 932
 933	pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
 934
 935	/*
 936	 * Percpu allocations are only scanned and not reported as leaks
 937	 * (min_count is set to 0).
 938	 */
 939	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 940		for_each_possible_cpu(cpu)
 941			create_object((unsigned long)per_cpu_ptr(ptr, cpu),
 942				      size, 0, gfp);
 943	else if (kmemleak_early_log)
 944		log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
 945}
 946EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
 947
 948/**
 949 * kmemleak_free - unregister a previously registered object
 950 * @ptr:	pointer to beginning of the object
 951 *
 952 * This function is called from the kernel allocators when an object (memory
 953 * block) is freed (kmem_cache_free, kfree, vfree etc.).
 954 */
 955void __ref kmemleak_free(const void *ptr)
 956{
 957	pr_debug("%s(0x%p)\n", __func__, ptr);
 958
 959	if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
 960		delete_object_full((unsigned long)ptr);
 961	else if (kmemleak_early_log)
 962		log_early(KMEMLEAK_FREE, ptr, 0, 0);
 963}
 964EXPORT_SYMBOL_GPL(kmemleak_free);
 965
 966/**
 967 * kmemleak_free_part - partially unregister a previously registered object
 968 * @ptr:	pointer to the beginning or inside the object. This also
 969 *		represents the start of the range to be freed
 970 * @size:	size to be unregistered
 971 *
 972 * This function is called when only a part of a memory block is freed
 973 * (usually from the bootmem allocator).
 974 */
 975void __ref kmemleak_free_part(const void *ptr, size_t size)
 976{
 977	pr_debug("%s(0x%p)\n", __func__, ptr);
 978
 979	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 980		delete_object_part((unsigned long)ptr, size);
 981	else if (kmemleak_early_log)
 982		log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
 983}
 984EXPORT_SYMBOL_GPL(kmemleak_free_part);
 985
 986/**
 987 * kmemleak_free_percpu - unregister a previously registered __percpu object
 988 * @ptr:	__percpu pointer to beginning of the object
 989 *
 990 * This function is called from the kernel percpu allocator when an object
 991 * (memory block) is freed (free_percpu).
 992 */
 993void __ref kmemleak_free_percpu(const void __percpu *ptr)
 994{
 995	unsigned int cpu;
 996
 997	pr_debug("%s(0x%p)\n", __func__, ptr);
 998
 999	if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
1000		for_each_possible_cpu(cpu)
1001			delete_object_full((unsigned long)per_cpu_ptr(ptr,
1002								      cpu));
1003	else if (kmemleak_early_log)
1004		log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
1005}
1006EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
1007
1008/**
1009 * kmemleak_update_trace - update object allocation stack trace
1010 * @ptr:	pointer to beginning of the object
1011 *
1012 * Override the object allocation stack trace for cases where the actual
1013 * allocation place is not always useful.
1014 */
1015void __ref kmemleak_update_trace(const void *ptr)
1016{
1017	struct kmemleak_object *object;
1018	unsigned long flags;
1019
1020	pr_debug("%s(0x%p)\n", __func__, ptr);
1021
1022	if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
1023		return;
1024
1025	object = find_and_get_object((unsigned long)ptr, 1);
1026	if (!object) {
1027#ifdef DEBUG
1028		kmemleak_warn("Updating stack trace for unknown object at %p\n",
1029			      ptr);
1030#endif
1031		return;
1032	}
1033
1034	spin_lock_irqsave(&object->lock, flags);
1035	object->trace_len = __save_stack_trace(object->trace);
1036	spin_unlock_irqrestore(&object->lock, flags);
1037
1038	put_object(object);
1039}
1040EXPORT_SYMBOL(kmemleak_update_trace);
1041
1042/**
1043 * kmemleak_not_leak - mark an allocated object as false positive
1044 * @ptr:	pointer to beginning of the object
1045 *
1046 * Calling this function on an object will cause the memory block to no longer
1047 * be reported as leak and always be scanned.
1048 */
1049void __ref kmemleak_not_leak(const void *ptr)
1050{
1051	pr_debug("%s(0x%p)\n", __func__, ptr);
1052
1053	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1054		make_gray_object((unsigned long)ptr);
1055	else if (kmemleak_early_log)
1056		log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
1057}
1058EXPORT_SYMBOL(kmemleak_not_leak);
1059
1060/**
1061 * kmemleak_ignore - ignore an allocated object
1062 * @ptr:	pointer to beginning of the object
1063 *
1064 * Calling this function on an object will cause the memory block to be
1065 * ignored (not scanned and not reported as a leak). This is usually done when
1066 * it is known that the corresponding block is not a leak and does not contain
1067 * any references to other allocated memory blocks.
1068 */
1069void __ref kmemleak_ignore(const void *ptr)
1070{
1071	pr_debug("%s(0x%p)\n", __func__, ptr);
1072
1073	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1074		make_black_object((unsigned long)ptr);
1075	else if (kmemleak_early_log)
1076		log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
1077}
1078EXPORT_SYMBOL(kmemleak_ignore);
1079
1080/**
1081 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1082 * @ptr:	pointer to beginning or inside the object. This also
1083 *		represents the start of the scan area
1084 * @size:	size of the scan area
1085 * @gfp:	kmalloc() flags used for kmemleak internal memory allocations
1086 *
1087 * This function is used when it is known that only certain parts of an object
1088 * contain references to other objects. Kmemleak will only scan these areas
1089 * reducing the number false negatives.
1090 */
1091void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1092{
1093	pr_debug("%s(0x%p)\n", __func__, ptr);
1094
1095	if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1096		add_scan_area((unsigned long)ptr, size, gfp);
1097	else if (kmemleak_early_log)
1098		log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
1099}
1100EXPORT_SYMBOL(kmemleak_scan_area);
1101
1102/**
1103 * kmemleak_no_scan - do not scan an allocated object
1104 * @ptr:	pointer to beginning of the object
1105 *
1106 * This function notifies kmemleak not to scan the given memory block. Useful
1107 * in situations where it is known that the given object does not contain any
1108 * references to other objects. Kmemleak will not scan such objects reducing
1109 * the number of false negatives.
1110 */
1111void __ref kmemleak_no_scan(const void *ptr)
1112{
1113	pr_debug("%s(0x%p)\n", __func__, ptr);
1114
1115	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1116		object_no_scan((unsigned long)ptr);
1117	else if (kmemleak_early_log)
1118		log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
1119}
1120EXPORT_SYMBOL(kmemleak_no_scan);
1121
1122/*
1123 * Update an object's checksum and return true if it was modified.
1124 */
1125static bool update_checksum(struct kmemleak_object *object)
1126{
1127	u32 old_csum = object->checksum;
1128
1129	if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1130		return false;
1131
1132	kasan_disable_current();
1133	object->checksum = crc32(0, (void *)object->pointer, object->size);
1134	kasan_enable_current();
1135
1136	return object->checksum != old_csum;
1137}
1138
1139/*
1140 * Memory scanning is a long process and it needs to be interruptable. This
1141 * function checks whether such interrupt condition occurred.
1142 */
1143static int scan_should_stop(void)
1144{
1145	if (!kmemleak_enabled)
1146		return 1;
1147
1148	/*
1149	 * This function may be called from either process or kthread context,
1150	 * hence the need to check for both stop conditions.
1151	 */
1152	if (current->mm)
1153		return signal_pending(current);
1154	else
1155		return kthread_should_stop();
1156
1157	return 0;
1158}
1159
1160/*
1161 * Scan a memory block (exclusive range) for valid pointers and add those
1162 * found to the gray list.
1163 */
1164static void scan_block(void *_start, void *_end,
1165		       struct kmemleak_object *scanned)
1166{
1167	unsigned long *ptr;
1168	unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1169	unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1170	unsigned long flags;
1171
1172	read_lock_irqsave(&kmemleak_lock, flags);
1173	for (ptr = start; ptr < end; ptr++) {
1174		struct kmemleak_object *object;
 
1175		unsigned long pointer;
1176
 
 
1177		if (scan_should_stop())
1178			break;
1179
1180		/* don't scan uninitialized memory */
1181		if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1182						  BYTES_PER_POINTER))
1183			continue;
1184
1185		kasan_disable_current();
1186		pointer = *ptr;
1187		kasan_enable_current();
1188
1189		if (pointer < min_addr || pointer >= max_addr)
1190			continue;
1191
1192		/*
1193		 * No need for get_object() here since we hold kmemleak_lock.
1194		 * object->use_count cannot be dropped to 0 while the object
1195		 * is still present in object_tree_root and object_list
1196		 * (with updates protected by kmemleak_lock).
1197		 */
1198		object = lookup_object(pointer, 1);
1199		if (!object)
1200			continue;
1201		if (object == scanned)
1202			/* self referenced, ignore */
 
1203			continue;
 
1204
1205		/*
1206		 * Avoid the lockdep recursive warning on object->lock being
1207		 * previously acquired in scan_object(). These locks are
1208		 * enclosed by scan_mutex.
1209		 */
1210		spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
 
1211		if (!color_white(object)) {
1212			/* non-orphan, ignored or new */
1213			spin_unlock(&object->lock);
 
1214			continue;
1215		}
1216
1217		/*
1218		 * Increase the object's reference count (number of pointers
1219		 * to the memory block). If this count reaches the required
1220		 * minimum, the object's color will become gray and it will be
1221		 * added to the gray_list.
1222		 */
1223		object->count++;
1224		if (color_gray(object)) {
1225			/* put_object() called when removing from gray_list */
1226			WARN_ON(!get_object(object));
1227			list_add_tail(&object->gray_list, &gray_list);
 
 
1228		}
1229		spin_unlock(&object->lock);
1230	}
1231	read_unlock_irqrestore(&kmemleak_lock, flags);
1232}
1233
1234/*
1235 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1236 */
1237static void scan_large_block(void *start, void *end)
1238{
1239	void *next;
1240
1241	while (start < end) {
1242		next = min(start + MAX_SCAN_SIZE, end);
1243		scan_block(start, next, NULL);
1244		start = next;
1245		cond_resched();
1246	}
1247}
1248
1249/*
1250 * Scan a memory block corresponding to a kmemleak_object. A condition is
1251 * that object->use_count >= 1.
1252 */
1253static void scan_object(struct kmemleak_object *object)
1254{
1255	struct kmemleak_scan_area *area;
 
1256	unsigned long flags;
1257
1258	/*
1259	 * Once the object->lock is acquired, the corresponding memory block
1260	 * cannot be freed (the same lock is acquired in delete_object).
1261	 */
1262	spin_lock_irqsave(&object->lock, flags);
1263	if (object->flags & OBJECT_NO_SCAN)
1264		goto out;
1265	if (!(object->flags & OBJECT_ALLOCATED))
1266		/* already freed object */
1267		goto out;
1268	if (hlist_empty(&object->area_list)) {
1269		void *start = (void *)object->pointer;
1270		void *end = (void *)(object->pointer + object->size);
1271		void *next;
1272
1273		do {
1274			next = min(start + MAX_SCAN_SIZE, end);
1275			scan_block(start, next, object);
1276
1277			start = next;
1278			if (start >= end)
1279				break;
1280
1281			spin_unlock_irqrestore(&object->lock, flags);
1282			cond_resched();
1283			spin_lock_irqsave(&object->lock, flags);
1284		} while (object->flags & OBJECT_ALLOCATED);
1285	} else
1286		hlist_for_each_entry(area, &object->area_list, node)
1287			scan_block((void *)area->start,
1288				   (void *)(area->start + area->size),
1289				   object);
1290out:
1291	spin_unlock_irqrestore(&object->lock, flags);
1292}
1293
1294/*
1295 * Scan the objects already referenced (gray objects). More objects will be
1296 * referenced and, if there are no memory leaks, all the objects are scanned.
1297 */
1298static void scan_gray_list(void)
1299{
1300	struct kmemleak_object *object, *tmp;
1301
1302	/*
1303	 * The list traversal is safe for both tail additions and removals
1304	 * from inside the loop. The kmemleak objects cannot be freed from
1305	 * outside the loop because their use_count was incremented.
1306	 */
1307	object = list_entry(gray_list.next, typeof(*object), gray_list);
1308	while (&object->gray_list != &gray_list) {
1309		cond_resched();
1310
1311		/* may add new objects to the list */
1312		if (!scan_should_stop())
1313			scan_object(object);
1314
1315		tmp = list_entry(object->gray_list.next, typeof(*object),
1316				 gray_list);
1317
1318		/* remove the object from the list and release it */
1319		list_del(&object->gray_list);
1320		put_object(object);
1321
1322		object = tmp;
1323	}
1324	WARN_ON(!list_empty(&gray_list));
1325}
1326
1327/*
1328 * Scan data sections and all the referenced memory blocks allocated via the
1329 * kernel's standard allocators. This function must be called with the
1330 * scan_mutex held.
1331 */
1332static void kmemleak_scan(void)
1333{
1334	unsigned long flags;
1335	struct kmemleak_object *object;
1336	int i;
1337	int new_leaks = 0;
1338
1339	jiffies_last_scan = jiffies;
1340
1341	/* prepare the kmemleak_object's */
1342	rcu_read_lock();
1343	list_for_each_entry_rcu(object, &object_list, object_list) {
1344		spin_lock_irqsave(&object->lock, flags);
1345#ifdef DEBUG
1346		/*
1347		 * With a few exceptions there should be a maximum of
1348		 * 1 reference to any object at this point.
1349		 */
1350		if (atomic_read(&object->use_count) > 1) {
1351			pr_debug("object->use_count = %d\n",
1352				 atomic_read(&object->use_count));
1353			dump_object_info(object);
1354		}
1355#endif
1356		/* reset the reference count (whiten the object) */
1357		object->count = 0;
1358		if (color_gray(object) && get_object(object))
1359			list_add_tail(&object->gray_list, &gray_list);
1360
1361		spin_unlock_irqrestore(&object->lock, flags);
1362	}
1363	rcu_read_unlock();
1364
1365	/* data/bss scanning */
1366	scan_large_block(_sdata, _edata);
1367	scan_large_block(__bss_start, __bss_stop);
1368
1369#ifdef CONFIG_SMP
1370	/* per-cpu sections scanning */
1371	for_each_possible_cpu(i)
1372		scan_large_block(__per_cpu_start + per_cpu_offset(i),
1373				 __per_cpu_end + per_cpu_offset(i));
1374#endif
1375
1376	/*
1377	 * Struct page scanning for each node.
1378	 */
1379	get_online_mems();
1380	for_each_online_node(i) {
1381		unsigned long start_pfn = node_start_pfn(i);
1382		unsigned long end_pfn = node_end_pfn(i);
 
1383		unsigned long pfn;
1384
1385		for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1386			struct page *page;
1387
1388			if (!pfn_valid(pfn))
1389				continue;
1390			page = pfn_to_page(pfn);
1391			/* only scan if page is in use */
1392			if (page_count(page) == 0)
1393				continue;
1394			scan_block(page, page + 1, NULL);
1395		}
1396	}
1397	put_online_mems();
1398
1399	/*
1400	 * Scanning the task stacks (may introduce false negatives).
1401	 */
1402	if (kmemleak_stack_scan) {
1403		struct task_struct *p, *g;
1404
1405		read_lock(&tasklist_lock);
1406		do_each_thread(g, p) {
1407			scan_block(task_stack_page(p), task_stack_page(p) +
1408				   THREAD_SIZE, NULL);
1409		} while_each_thread(g, p);
1410		read_unlock(&tasklist_lock);
1411	}
1412
1413	/*
1414	 * Scan the objects already referenced from the sections scanned
1415	 * above.
1416	 */
1417	scan_gray_list();
1418
1419	/*
1420	 * Check for new or unreferenced objects modified since the previous
1421	 * scan and color them gray until the next scan.
1422	 */
1423	rcu_read_lock();
1424	list_for_each_entry_rcu(object, &object_list, object_list) {
1425		spin_lock_irqsave(&object->lock, flags);
1426		if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1427		    && update_checksum(object) && get_object(object)) {
1428			/* color it gray temporarily */
1429			object->count = object->min_count;
1430			list_add_tail(&object->gray_list, &gray_list);
1431		}
1432		spin_unlock_irqrestore(&object->lock, flags);
1433	}
1434	rcu_read_unlock();
1435
1436	/*
1437	 * Re-scan the gray list for modified unreferenced objects.
1438	 */
1439	scan_gray_list();
1440
1441	/*
1442	 * If scanning was stopped do not report any new unreferenced objects.
1443	 */
1444	if (scan_should_stop())
1445		return;
1446
1447	/*
1448	 * Scanning result reporting.
1449	 */
1450	rcu_read_lock();
1451	list_for_each_entry_rcu(object, &object_list, object_list) {
1452		spin_lock_irqsave(&object->lock, flags);
1453		if (unreferenced_object(object) &&
1454		    !(object->flags & OBJECT_REPORTED)) {
1455			object->flags |= OBJECT_REPORTED;
1456			new_leaks++;
1457		}
1458		spin_unlock_irqrestore(&object->lock, flags);
1459	}
1460	rcu_read_unlock();
1461
1462	if (new_leaks) {
1463		kmemleak_found_leaks = true;
1464
1465		pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1466			new_leaks);
1467	}
1468
1469}
1470
1471/*
1472 * Thread function performing automatic memory scanning. Unreferenced objects
1473 * at the end of a memory scan are reported but only the first time.
1474 */
1475static int kmemleak_scan_thread(void *arg)
1476{
1477	static int first_run = 1;
1478
1479	pr_info("Automatic memory scanning thread started\n");
1480	set_user_nice(current, 10);
1481
1482	/*
1483	 * Wait before the first scan to allow the system to fully initialize.
1484	 */
1485	if (first_run) {
1486		first_run = 0;
1487		ssleep(SECS_FIRST_SCAN);
1488	}
1489
1490	while (!kthread_should_stop()) {
1491		signed long timeout = jiffies_scan_wait;
1492
1493		mutex_lock(&scan_mutex);
1494		kmemleak_scan();
1495		mutex_unlock(&scan_mutex);
1496
1497		/* wait before the next scan */
1498		while (timeout && !kthread_should_stop())
1499			timeout = schedule_timeout_interruptible(timeout);
1500	}
1501
1502	pr_info("Automatic memory scanning thread ended\n");
1503
1504	return 0;
1505}
1506
1507/*
1508 * Start the automatic memory scanning thread. This function must be called
1509 * with the scan_mutex held.
1510 */
1511static void start_scan_thread(void)
1512{
1513	if (scan_thread)
1514		return;
1515	scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1516	if (IS_ERR(scan_thread)) {
1517		pr_warn("Failed to create the scan thread\n");
1518		scan_thread = NULL;
1519	}
1520}
1521
1522/*
1523 * Stop the automatic memory scanning thread. This function must be called
1524 * with the scan_mutex held.
1525 */
1526static void stop_scan_thread(void)
1527{
1528	if (scan_thread) {
1529		kthread_stop(scan_thread);
1530		scan_thread = NULL;
1531	}
1532}
1533
1534/*
1535 * Iterate over the object_list and return the first valid object at or after
1536 * the required position with its use_count incremented. The function triggers
1537 * a memory scanning when the pos argument points to the first position.
1538 */
1539static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1540{
1541	struct kmemleak_object *object;
1542	loff_t n = *pos;
1543	int err;
1544
1545	err = mutex_lock_interruptible(&scan_mutex);
1546	if (err < 0)
1547		return ERR_PTR(err);
1548
1549	rcu_read_lock();
1550	list_for_each_entry_rcu(object, &object_list, object_list) {
1551		if (n-- > 0)
1552			continue;
1553		if (get_object(object))
1554			goto out;
1555	}
1556	object = NULL;
1557out:
1558	return object;
1559}
1560
1561/*
1562 * Return the next object in the object_list. The function decrements the
1563 * use_count of the previous object and increases that of the next one.
1564 */
1565static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1566{
1567	struct kmemleak_object *prev_obj = v;
1568	struct kmemleak_object *next_obj = NULL;
1569	struct kmemleak_object *obj = prev_obj;
1570
1571	++(*pos);
1572
1573	list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
 
 
1574		if (get_object(obj)) {
1575			next_obj = obj;
1576			break;
1577		}
1578	}
1579
1580	put_object(prev_obj);
1581	return next_obj;
1582}
1583
1584/*
1585 * Decrement the use_count of the last object required, if any.
1586 */
1587static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1588{
1589	if (!IS_ERR(v)) {
1590		/*
1591		 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1592		 * waiting was interrupted, so only release it if !IS_ERR.
1593		 */
1594		rcu_read_unlock();
1595		mutex_unlock(&scan_mutex);
1596		if (v)
1597			put_object(v);
1598	}
1599}
1600
1601/*
1602 * Print the information for an unreferenced object to the seq file.
1603 */
1604static int kmemleak_seq_show(struct seq_file *seq, void *v)
1605{
1606	struct kmemleak_object *object = v;
1607	unsigned long flags;
1608
1609	spin_lock_irqsave(&object->lock, flags);
1610	if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1611		print_unreferenced(seq, object);
1612	spin_unlock_irqrestore(&object->lock, flags);
1613	return 0;
1614}
1615
1616static const struct seq_operations kmemleak_seq_ops = {
1617	.start = kmemleak_seq_start,
1618	.next  = kmemleak_seq_next,
1619	.stop  = kmemleak_seq_stop,
1620	.show  = kmemleak_seq_show,
1621};
1622
1623static int kmemleak_open(struct inode *inode, struct file *file)
1624{
1625	return seq_open(file, &kmemleak_seq_ops);
1626}
1627
 
 
 
 
 
1628static int dump_str_object_info(const char *str)
1629{
1630	unsigned long flags;
1631	struct kmemleak_object *object;
1632	unsigned long addr;
1633
1634	if (kstrtoul(str, 0, &addr))
1635		return -EINVAL;
1636	object = find_and_get_object(addr, 0);
1637	if (!object) {
1638		pr_info("Unknown object at 0x%08lx\n", addr);
1639		return -EINVAL;
1640	}
1641
1642	spin_lock_irqsave(&object->lock, flags);
1643	dump_object_info(object);
1644	spin_unlock_irqrestore(&object->lock, flags);
1645
1646	put_object(object);
1647	return 0;
1648}
1649
1650/*
1651 * We use grey instead of black to ensure we can do future scans on the same
1652 * objects. If we did not do future scans these black objects could
1653 * potentially contain references to newly allocated objects in the future and
1654 * we'd end up with false positives.
1655 */
1656static void kmemleak_clear(void)
1657{
1658	struct kmemleak_object *object;
1659	unsigned long flags;
1660
1661	rcu_read_lock();
1662	list_for_each_entry_rcu(object, &object_list, object_list) {
1663		spin_lock_irqsave(&object->lock, flags);
1664		if ((object->flags & OBJECT_REPORTED) &&
1665		    unreferenced_object(object))
1666			__paint_it(object, KMEMLEAK_GREY);
1667		spin_unlock_irqrestore(&object->lock, flags);
1668	}
1669	rcu_read_unlock();
1670
1671	kmemleak_found_leaks = false;
1672}
1673
1674static void __kmemleak_do_cleanup(void);
1675
1676/*
1677 * File write operation to configure kmemleak at run-time. The following
1678 * commands can be written to the /sys/kernel/debug/kmemleak file:
1679 *   off	- disable kmemleak (irreversible)
1680 *   stack=on	- enable the task stacks scanning
1681 *   stack=off	- disable the tasks stacks scanning
1682 *   scan=on	- start the automatic memory scanning thread
1683 *   scan=off	- stop the automatic memory scanning thread
1684 *   scan=...	- set the automatic memory scanning period in seconds (0 to
1685 *		  disable it)
1686 *   scan	- trigger a memory scan
1687 *   clear	- mark all current reported unreferenced kmemleak objects as
1688 *		  grey to ignore printing them, or free all kmemleak objects
1689 *		  if kmemleak has been disabled.
1690 *   dump=...	- dump information about the object found at the given address
1691 */
1692static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1693			      size_t size, loff_t *ppos)
1694{
1695	char buf[64];
1696	int buf_size;
1697	int ret;
1698
 
 
 
1699	buf_size = min(size, (sizeof(buf) - 1));
1700	if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1701		return -EFAULT;
1702	buf[buf_size] = 0;
1703
1704	ret = mutex_lock_interruptible(&scan_mutex);
1705	if (ret < 0)
1706		return ret;
1707
1708	if (strncmp(buf, "clear", 5) == 0) {
1709		if (kmemleak_enabled)
1710			kmemleak_clear();
1711		else
1712			__kmemleak_do_cleanup();
1713		goto out;
1714	}
1715
1716	if (!kmemleak_enabled) {
1717		ret = -EBUSY;
1718		goto out;
1719	}
1720
1721	if (strncmp(buf, "off", 3) == 0)
1722		kmemleak_disable();
1723	else if (strncmp(buf, "stack=on", 8) == 0)
1724		kmemleak_stack_scan = 1;
1725	else if (strncmp(buf, "stack=off", 9) == 0)
1726		kmemleak_stack_scan = 0;
1727	else if (strncmp(buf, "scan=on", 7) == 0)
1728		start_scan_thread();
1729	else if (strncmp(buf, "scan=off", 8) == 0)
1730		stop_scan_thread();
1731	else if (strncmp(buf, "scan=", 5) == 0) {
1732		unsigned long secs;
1733
1734		ret = kstrtoul(buf + 5, 0, &secs);
1735		if (ret < 0)
1736			goto out;
1737		stop_scan_thread();
1738		if (secs) {
1739			jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1740			start_scan_thread();
1741		}
1742	} else if (strncmp(buf, "scan", 4) == 0)
1743		kmemleak_scan();
 
 
1744	else if (strncmp(buf, "dump=", 5) == 0)
1745		ret = dump_str_object_info(buf + 5);
1746	else
1747		ret = -EINVAL;
1748
1749out:
1750	mutex_unlock(&scan_mutex);
1751	if (ret < 0)
1752		return ret;
1753
1754	/* ignore the rest of the buffer, only one command at a time */
1755	*ppos += size;
1756	return size;
1757}
1758
1759static const struct file_operations kmemleak_fops = {
1760	.owner		= THIS_MODULE,
1761	.open		= kmemleak_open,
1762	.read		= seq_read,
1763	.write		= kmemleak_write,
1764	.llseek		= seq_lseek,
1765	.release	= seq_release,
1766};
1767
1768static void __kmemleak_do_cleanup(void)
1769{
1770	struct kmemleak_object *object;
1771
1772	rcu_read_lock();
1773	list_for_each_entry_rcu(object, &object_list, object_list)
1774		delete_object_full(object->pointer);
1775	rcu_read_unlock();
1776}
1777
1778/*
1779 * Stop the memory scanning thread and free the kmemleak internal objects if
1780 * no previous scan thread (otherwise, kmemleak may still have some useful
1781 * information on memory leaks).
1782 */
1783static void kmemleak_do_cleanup(struct work_struct *work)
1784{
1785	stop_scan_thread();
 
1786
1787	/*
1788	 * Once the scan thread has stopped, it is safe to no longer track
1789	 * object freeing. Ordering of the scan thread stopping and the memory
1790	 * accesses below is guaranteed by the kthread_stop() function.
1791	 */
1792	kmemleak_free_enabled = 0;
1793
1794	if (!kmemleak_found_leaks)
1795		__kmemleak_do_cleanup();
1796	else
1797		pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
 
 
 
1798}
1799
1800static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1801
1802/*
1803 * Disable kmemleak. No memory allocation/freeing will be traced once this
1804 * function is called. Disabling kmemleak is an irreversible operation.
1805 */
1806static void kmemleak_disable(void)
1807{
1808	/* atomically check whether it was already invoked */
1809	if (cmpxchg(&kmemleak_error, 0, 1))
1810		return;
1811
1812	/* stop any memory operation tracing */
1813	kmemleak_enabled = 0;
1814
1815	/* check whether it is too early for a kernel thread */
1816	if (kmemleak_initialized)
1817		schedule_work(&cleanup_work);
1818	else
1819		kmemleak_free_enabled = 0;
1820
1821	pr_info("Kernel memory leak detector disabled\n");
1822}
1823
1824/*
1825 * Allow boot-time kmemleak disabling (enabled by default).
1826 */
1827static int kmemleak_boot_config(char *str)
1828{
1829	if (!str)
1830		return -EINVAL;
1831	if (strcmp(str, "off") == 0)
1832		kmemleak_disable();
1833	else if (strcmp(str, "on") == 0)
1834		kmemleak_skip_disable = 1;
1835	else
1836		return -EINVAL;
1837	return 0;
1838}
1839early_param("kmemleak", kmemleak_boot_config);
1840
1841static void __init print_log_trace(struct early_log *log)
1842{
1843	struct stack_trace trace;
1844
1845	trace.nr_entries = log->trace_len;
1846	trace.entries = log->trace;
1847
1848	pr_notice("Early log backtrace:\n");
1849	print_stack_trace(&trace, 2);
1850}
1851
1852/*
1853 * Kmemleak initialization.
1854 */
1855void __init kmemleak_init(void)
1856{
1857	int i;
1858	unsigned long flags;
1859
1860#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1861	if (!kmemleak_skip_disable) {
1862		kmemleak_early_log = 0;
1863		kmemleak_disable();
1864		return;
1865	}
1866#endif
1867
1868	jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1869	jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1870
1871	object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1872	scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
 
1873
1874	if (crt_early_log > ARRAY_SIZE(early_log))
1875		pr_warn("Early log buffer exceeded (%d), please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n",
1876			crt_early_log);
1877
1878	/* the kernel is still in UP mode, so disabling the IRQs is enough */
1879	local_irq_save(flags);
1880	kmemleak_early_log = 0;
1881	if (kmemleak_error) {
1882		local_irq_restore(flags);
1883		return;
1884	} else {
1885		kmemleak_enabled = 1;
1886		kmemleak_free_enabled = 1;
1887	}
1888	local_irq_restore(flags);
1889
1890	/*
1891	 * This is the point where tracking allocations is safe. Automatic
1892	 * scanning is started during the late initcall. Add the early logged
1893	 * callbacks to the kmemleak infrastructure.
1894	 */
1895	for (i = 0; i < crt_early_log; i++) {
1896		struct early_log *log = &early_log[i];
1897
1898		switch (log->op_type) {
1899		case KMEMLEAK_ALLOC:
1900			early_alloc(log);
1901			break;
1902		case KMEMLEAK_ALLOC_PERCPU:
1903			early_alloc_percpu(log);
1904			break;
1905		case KMEMLEAK_FREE:
1906			kmemleak_free(log->ptr);
1907			break;
1908		case KMEMLEAK_FREE_PART:
1909			kmemleak_free_part(log->ptr, log->size);
1910			break;
1911		case KMEMLEAK_FREE_PERCPU:
1912			kmemleak_free_percpu(log->ptr);
1913			break;
1914		case KMEMLEAK_NOT_LEAK:
1915			kmemleak_not_leak(log->ptr);
1916			break;
1917		case KMEMLEAK_IGNORE:
1918			kmemleak_ignore(log->ptr);
1919			break;
1920		case KMEMLEAK_SCAN_AREA:
1921			kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
1922			break;
1923		case KMEMLEAK_NO_SCAN:
1924			kmemleak_no_scan(log->ptr);
1925			break;
1926		default:
1927			kmemleak_warn("Unknown early log operation: %d\n",
1928				      log->op_type);
1929		}
1930
1931		if (kmemleak_warning) {
1932			print_log_trace(log);
1933			kmemleak_warning = 0;
1934		}
1935	}
1936}
1937
1938/*
1939 * Late initialization function.
1940 */
1941static int __init kmemleak_late_init(void)
1942{
1943	struct dentry *dentry;
1944
1945	kmemleak_initialized = 1;
1946
1947	if (kmemleak_error) {
1948		/*
1949		 * Some error occurred and kmemleak was disabled. There is a
1950		 * small chance that kmemleak_disable() was called immediately
1951		 * after setting kmemleak_initialized and we may end up with
1952		 * two clean-up threads but serialized by scan_mutex.
1953		 */
1954		schedule_work(&cleanup_work);
1955		return -ENOMEM;
1956	}
1957
1958	dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1959				     &kmemleak_fops);
1960	if (!dentry)
1961		pr_warn("Failed to create the debugfs kmemleak file\n");
1962	mutex_lock(&scan_mutex);
1963	start_scan_thread();
1964	mutex_unlock(&scan_mutex);
1965
1966	pr_info("Kernel memory leak detector initialized\n");
1967
1968	return 0;
1969}
1970late_initcall(kmemleak_late_init);