| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Catalin Marinas | 5574 | 73.26% | 49 | 28.82% |
| Liu Shixin | 281 | 3.69% | 9 | 5.29% |
| Patrick Wang | 280 | 3.68% | 4 | 2.35% |
| Waiman Long | 206 | 2.71% | 7 | 4.12% |
| Michel Lespinasse | 152 | 2.00% | 1 | 0.59% |
| Luis R. Rodriguez | 151 | 1.98% | 4 | 2.35% |
| Vincent Whitchurch | 130 | 1.71% | 2 | 1.18% |
| Kuan-Ying Lee | 107 | 1.41% | 3 | 1.76% |
| zhaoyang | 91 | 1.20% | 2 | 1.18% |
| Sergey Senozhatsky | 80 | 1.05% | 1 | 0.59% |
| Li Zefan | 78 | 1.03% | 4 | 2.35% |
| Andrey Konovalov | 77 | 1.01% | 2 | 1.18% |
| He Zhe | 38 | 0.50% | 1 | 0.59% |
| Yanfei Xu | 31 | 0.41% | 1 | 0.59% |
| Linus Torvalds (pre-git) | 29 | 0.38% | 10 | 5.88% |
| Jason Baron | 27 | 0.35% | 1 | 0.59% |
| Joe Perches | 24 | 0.32% | 3 | 1.76% |
| Lang Yu | 16 | 0.21% | 1 | 0.59% |
| Andrey Ryabinin | 15 | 0.20% | 1 | 0.59% |
| matthias.kunze@gmx-topmail.de | 14 | 0.18% | 1 | 0.59% |
| Sri Krishna chowdary | 13 | 0.17% | 1 | 0.59% |
| Oscar Salvador | 12 | 0.16% | 1 | 0.59% |
| Vegard Nossum | 12 | 0.16% | 1 | 0.59% |
| Abhijit Pawar | 11 | 0.14% | 1 | 0.59% |
| Thomas Gleixner | 10 | 0.13% | 2 | 1.18% |
| Andy Shevchenko | 10 | 0.13% | 1 | 0.59% |
| Qian Cai | 9 | 0.12% | 2 | 1.18% |
| Laura Abbott | 8 | 0.11% | 1 | 0.59% |
| Ingo Molnar | 7 | 0.09% | 3 | 1.76% |
| Dmitriy Vyukov | 7 | 0.09% | 2 | 1.18% |
| Xiaolei Wang | 6 | 0.08% | 2 | 1.18% |
| Jim Cromie | 6 | 0.08% | 2 | 1.18% |
| Michael Wang | 6 | 0.08% | 1 | 0.59% |
| Kees Cook | 5 | 0.07% | 2 | 1.18% |
| Andrew Morton | 5 | 0.07% | 2 | 1.18% |
| Rusty Russell | 5 | 0.07% | 2 | 1.18% |
| Davidlohr Bueso A | 5 | 0.07% | 1 | 0.59% |
| Arnd Bergmann | 5 | 0.07% | 1 | 0.59% |
| Pekka J Enberg | 5 | 0.07% | 1 | 0.59% |
| Nathan Chancellor | 4 | 0.05% | 1 | 0.59% |
| Sasha Levin | 4 | 0.05% | 1 | 0.59% |
| Alexander Potapenko | 3 | 0.04% | 1 | 0.59% |
| Dipankar Sarma | 3 | 0.04% | 1 | 0.59% |
| Alex Riesen | 3 | 0.04% | 1 | 0.59% |
| Franck Bui-Huu | 3 | 0.04% | 1 | 0.59% |
| Mike Rapoport | 3 | 0.04% | 2 | 1.18% |
| Andi Kleen | 3 | 0.04% | 1 | 0.59% |
| Eric Dumazet | 3 | 0.04% | 2 | 1.18% |
| Larry Finger | 2 | 0.03% | 1 | 0.59% |
| Vinayak Menon | 2 | 0.03% | 1 | 0.59% |
| Adrian Bunk | 2 | 0.03% | 1 | 0.59% |
| David Chinner | 2 | 0.03% | 1 | 0.59% |
| Cody P Schafer | 2 | 0.03% | 1 | 0.59% |
| Vladimir Davydov | 2 | 0.03% | 1 | 0.59% |
| Tiejun Chen | 2 | 0.03% | 1 | 0.59% |
| Arjan van de Ven | 2 | 0.03% | 1 | 0.59% |
| Randy Dunlap | 1 | 0.01% | 1 | 0.59% |
| Yinghai Lu | 1 | 0.01% | 1 | 0.59% |
| Bhaskar Chowdhury | 1 | 0.01% | 1 | 0.59% |
| Clément Leger | 1 | 0.01% | 1 | 0.59% |
| Dou Liyang | 1 | 0.01% | 1 | 0.59% |
| Jianpeng Ma | 1 | 0.01% | 1 | 0.59% |
| Lucas De Marchi | 1 | 0.01% | 1 | 0.59% |
| Changbin Du | 1 | 0.01% | 1 | 0.59% |
| André Almeida | 1 | 0.01% | 1 | 0.59% |
| Kamezawa Hiroyuki | 1 | 0.01% | 1 | 0.59% |
| Holger Hans Peter Freyther | 1 | 0.01% | 1 | 0.59% |
| Paul Gortmaker | 1 | 0.01% | 1 | 0.59% |
| Arun Sharma | 1 | 0.01% | 1 | 0.59% |
| Uwe Kleine-König | 1 | 0.01% | 1 | 0.59% |
| Konstantin Khlebnikov | 1 | 0.01% | 1 | 0.59% |
| Total | 7608 | 170 |
// SPDX-License-Identifier: GPL-2.0-only /* * mm/kmemleak.c * * Copyright (C) 2008 ARM Limited * Written by Catalin Marinas <catalin.marinas@arm.com> * * For more information on the algorithm and kmemleak usage, please see * Documentation/dev-tools/kmemleak.rst. * * Notes on locking * ---------------- * * The following locks and mutexes are used by kmemleak: * * - kmemleak_lock (raw_spinlock_t): protects the object_list as well as * del_state modifications and accesses to the object trees * (object_tree_root, object_phys_tree_root, object_percpu_tree_root). The * object_list is the main list holding the metadata (struct * kmemleak_object) for the allocated memory blocks. The object trees are * red black trees used to look-up metadata based on a pointer to the * corresponding memory block. The kmemleak_object structures are added to * the object_list and the object tree root in the create_object() function * called from the kmemleak_alloc{,_phys,_percpu}() callback and removed in * delete_object() called from the kmemleak_free{,_phys,_percpu}() callback * - kmemleak_object.lock (raw_spinlock_t): protects a kmemleak_object. * Accesses to the metadata (e.g. count) are protected by this lock. Note * that some members of this structure may be protected by other means * (atomic or kmemleak_lock). This lock is also held when scanning the * corresponding memory block to avoid the kernel freeing it via the * kmemleak_free() callback. This is less heavyweight than holding a global * lock like kmemleak_lock during scanning. * - scan_mutex (mutex): ensures that only one thread may scan the memory for * unreferenced objects at a time. The gray_list contains the objects which * are already referenced or marked as false positives and need to be * scanned. This list is only modified during a scanning episode when the * scan_mutex is held. At the end of a scan, the gray_list is always empty. * Note that the kmemleak_object.use_count is incremented when an object is * added to the gray_list and therefore cannot be freed. This mutex also * prevents multiple users of the "kmemleak" debugfs file together with * modifications to the memory scanning parameters including the scan_thread * pointer * * Locks and mutexes are acquired/nested in the following order: * * scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING) * * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex * regions. * * The kmemleak_object structures have a use_count incremented or decremented * using the get_object()/put_object() functions. When the use_count becomes * 0, this count can no longer be incremented and put_object() schedules the * kmemleak_object freeing via an RCU callback. All calls to the get_object() * function must be protected by rcu_read_lock() to avoid accessing a freed * structure. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/init.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/sched/signal.h> #include <linux/sched/task.h> #include <linux/sched/task_stack.h> #include <linux/jiffies.h> #include <linux/delay.h> #include <linux/export.h> #include <linux/kthread.h> #include <linux/rbtree.h> #include <linux/fs.h> #include <linux/debugfs.h> #include <linux/seq_file.h> #include <linux/cpumask.h> #include <linux/spinlock.h> #include <linux/module.h> #include <linux/mutex.h> #include <linux/rcupdate.h> #include <linux/stacktrace.h> #include <linux/stackdepot.h> #include <linux/cache.h> #include <linux/percpu.h> #include <linux/memblock.h> #include <linux/pfn.h> #include <linux/mmzone.h> #include <linux/slab.h> #include <linux/thread_info.h> #include <linux/err.h> #include <linux/uaccess.h> #include <linux/string.h> #include <linux/nodemask.h> #include <linux/mm.h> #include <linux/workqueue.h> #include <linux/crc32.h> #include <asm/sections.h> #include <asm/processor.h> #include <linux/atomic.h> #include <linux/kasan.h> #include <linux/kfence.h> #include <linux/kmemleak.h> #include <linux/memory_hotplug.h> /* * Kmemleak configuration and common defines. */ #define MAX_TRACE 16 /* stack trace length */ #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */ #define SECS_FIRST_SCAN 60 /* delay before the first scan */ #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */ #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */ #define BYTES_PER_POINTER sizeof(void *) /* scanning area inside a memory block */ struct kmemleak_scan_area { struct hlist_node node; unsigned long start; size_t size; }; #define KMEMLEAK_GREY 0 #define KMEMLEAK_BLACK -1 /* * Structure holding the metadata for each allocated memory block. * Modifications to such objects should be made while holding the * object->lock. Insertions or deletions from object_list, gray_list or * rb_node are already protected by the corresponding locks or mutex (see * the notes on locking above). These objects are reference-counted * (use_count) and freed using the RCU mechanism. */ struct kmemleak_object { raw_spinlock_t lock; unsigned int flags; /* object status flags */ struct list_head object_list; struct list_head gray_list; struct rb_node rb_node; struct rcu_head rcu; /* object_list lockless traversal */ /* object usage count; object freed when use_count == 0 */ atomic_t use_count; unsigned int del_state; /* deletion state */ unsigned long pointer; size_t size; /* pass surplus references to this pointer */ unsigned long excess_ref; /* minimum number of a pointers found before it is considered leak */ int min_count; /* the total number of pointers found pointing to this object */ int count; /* checksum for detecting modified objects */ u32 checksum; depot_stack_handle_t trace_handle; /* memory ranges to be scanned inside an object (empty for all) */ struct hlist_head area_list; unsigned long jiffies; /* creation timestamp */ pid_t pid; /* pid of the current task */ char comm[TASK_COMM_LEN]; /* executable name */ }; /* flag representing the memory block allocation status */ #define OBJECT_ALLOCATED (1 << 0) /* flag set after the first reporting of an unreference object */ #define OBJECT_REPORTED (1 << 1) /* flag set to not scan the object */ #define OBJECT_NO_SCAN (1 << 2) /* flag set to fully scan the object when scan_area allocation failed */ #define OBJECT_FULL_SCAN (1 << 3) /* flag set for object allocated with physical address */ #define OBJECT_PHYS (1 << 4) /* flag set for per-CPU pointers */ #define OBJECT_PERCPU (1 << 5) /* set when __remove_object() called */ #define DELSTATE_REMOVED (1 << 0) /* set to temporarily prevent deletion from object_list */ #define DELSTATE_NO_DELETE (1 << 1) #define HEX_PREFIX " " /* number of bytes to print per line; must be 16 or 32 */ #define HEX_ROW_SIZE 16 /* number of bytes to print at a time (1, 2, 4, 8) */ #define HEX_GROUP_SIZE 1 /* include ASCII after the hex output */ #define HEX_ASCII 1 /* max number of lines to be printed */ #define HEX_MAX_LINES 2 /* the list of all allocated objects */ static LIST_HEAD(object_list); /* the list of gray-colored objects (see color_gray comment below) */ static LIST_HEAD(gray_list); /* memory pool allocation */ static struct kmemleak_object mem_pool[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE]; static int mem_pool_free_count = ARRAY_SIZE(mem_pool); static LIST_HEAD(mem_pool_free_list); /* search tree for object boundaries */ static struct rb_root object_tree_root = RB_ROOT; /* search tree for object (with OBJECT_PHYS flag) boundaries */ static struct rb_root object_phys_tree_root = RB_ROOT; /* search tree for object (with OBJECT_PERCPU flag) boundaries */ static struct rb_root object_percpu_tree_root = RB_ROOT; /* protecting the access to object_list, object_tree_root (or object_phys_tree_root) */ static DEFINE_RAW_SPINLOCK(kmemleak_lock); /* allocation caches for kmemleak internal data */ static struct kmem_cache *object_cache; static struct kmem_cache *scan_area_cache; /* set if tracing memory operations is enabled */ static int kmemleak_enabled = 1; /* same as above but only for the kmemleak_free() callback */ static int kmemleak_free_enabled = 1; /* set in the late_initcall if there were no errors */ static int kmemleak_late_initialized; /* set if a kmemleak warning was issued */ static int kmemleak_warning; /* set if a fatal kmemleak error has occurred */ static int kmemleak_error; /* minimum and maximum address that may be valid pointers */ static unsigned long min_addr = ULONG_MAX; static unsigned long max_addr; static struct task_struct *scan_thread; /* used to avoid reporting of recently allocated objects */ static unsigned long jiffies_min_age; static unsigned long jiffies_last_scan; /* delay between automatic memory scannings */ static unsigned long jiffies_scan_wait; /* enables or disables the task stacks scanning */ static int kmemleak_stack_scan = 1; /* protects the memory scanning, parameters and debug/kmemleak file access */ static DEFINE_MUTEX(scan_mutex); /* setting kmemleak=on, will set this var, skipping the disable */ static int kmemleak_skip_disable; /* If there are leaks that can be reported */ static bool kmemleak_found_leaks; static bool kmemleak_verbose; module_param_named(verbose, kmemleak_verbose, bool, 0600); static void kmemleak_disable(void); /* * Print a warning and dump the stack trace. */ #define kmemleak_warn(x...) do { \ pr_warn(x); \ dump_stack(); \ kmemleak_warning = 1; \ } while (0) /* * Macro invoked when a serious kmemleak condition occurred and cannot be * recovered from. Kmemleak will be disabled and further allocation/freeing * tracing no longer available. */ #define kmemleak_stop(x...) do { \ kmemleak_warn(x); \ kmemleak_disable(); \ } while (0) #define warn_or_seq_printf(seq, fmt, ...) do { \ if (seq) \ seq_printf(seq, fmt, ##__VA_ARGS__); \ else \ pr_warn(fmt, ##__VA_ARGS__); \ } while (0) static void warn_or_seq_hex_dump(struct seq_file *seq, int prefix_type, int rowsize, int groupsize, const void *buf, size_t len, bool ascii) { if (seq) seq_hex_dump(seq, HEX_PREFIX, prefix_type, rowsize, groupsize, buf, len, ascii); else print_hex_dump(KERN_WARNING, pr_fmt(HEX_PREFIX), prefix_type, rowsize, groupsize, buf, len, ascii); } /* * Printing of the objects hex dump to the seq file. The number of lines to be * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called * with the object->lock held. */ static void hex_dump_object(struct seq_file *seq, struct kmemleak_object *object) { const u8 *ptr = (const u8 *)object->pointer; size_t len; if (WARN_ON_ONCE(object->flags & (OBJECT_PHYS | OBJECT_PERCPU))) return; /* limit the number of lines to HEX_MAX_LINES */ len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE); warn_or_seq_printf(seq, " hex dump (first %zu bytes):\n", len); kasan_disable_current(); warn_or_seq_hex_dump(seq, DUMP_PREFIX_NONE, HEX_ROW_SIZE, HEX_GROUP_SIZE, kasan_reset_tag((void *)ptr), len, HEX_ASCII); kasan_enable_current(); } /* * Object colors, encoded with count and min_count: * - white - orphan object, not enough references to it (count < min_count) * - gray - not orphan, not marked as false positive (min_count == 0) or * sufficient references to it (count >= min_count) * - black - ignore, it doesn't contain references (e.g. text section) * (min_count == -1). No function defined for this color. * Newly created objects don't have any color assigned (object->count == -1) * before the next memory scan when they become white. */ static bool color_white(const struct kmemleak_object *object) { return object->count != KMEMLEAK_BLACK && object->count < object->min_count; } static bool color_gray(const struct kmemleak_object *object) { return object->min_count != KMEMLEAK_BLACK && object->count >= object->min_count; } /* * Objects are considered unreferenced only if their color is white, they have * not be deleted and have a minimum age to avoid false positives caused by * pointers temporarily stored in CPU registers. */ static bool unreferenced_object(struct kmemleak_object *object) { return (color_white(object) && object->flags & OBJECT_ALLOCATED) && time_before_eq(object->jiffies + jiffies_min_age, jiffies_last_scan); } /* * Printing of the unreferenced objects information to the seq file. The * print_unreferenced function must be called with the object->lock held. */ static void print_unreferenced(struct seq_file *seq, struct kmemleak_object *object) { int i; unsigned long *entries; unsigned int nr_entries; nr_entries = stack_depot_fetch(object->trace_handle, &entries); warn_or_seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n", object->pointer, object->size); warn_or_seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n", object->comm, object->pid, object->jiffies); hex_dump_object(seq, object); warn_or_seq_printf(seq, " backtrace (crc %x):\n", object->checksum); for (i = 0; i < nr_entries; i++) { void *ptr = (void *)entries[i]; warn_or_seq_printf(seq, " [<%pK>] %pS\n", ptr, ptr); } } /* * Print the kmemleak_object information. This function is used mainly for * debugging special cases when kmemleak operations. It must be called with * the object->lock held. */ static void dump_object_info(struct kmemleak_object *object) { pr_notice("Object 0x%08lx (size %zu):\n", object->pointer, object->size); pr_notice(" comm \"%s\", pid %d, jiffies %lu\n", object->comm, object->pid, object->jiffies); pr_notice(" min_count = %d\n", object->min_count); pr_notice(" count = %d\n", object->count); pr_notice(" flags = 0x%x\n", object->flags); pr_notice(" checksum = %u\n", object->checksum); pr_notice(" backtrace:\n"); if (object->trace_handle) stack_depot_print(object->trace_handle); } static struct rb_root *object_tree(unsigned long objflags) { if (objflags & OBJECT_PHYS) return &object_phys_tree_root; if (objflags & OBJECT_PERCPU) return &object_percpu_tree_root; return &object_tree_root; } /* * Look-up a memory block metadata (kmemleak_object) in the object search * tree based on a pointer value. If alias is 0, only values pointing to the * beginning of the memory block are allowed. The kmemleak_lock must be held * when calling this function. */ static struct kmemleak_object *__lookup_object(unsigned long ptr, int alias, unsigned int objflags) { struct rb_node *rb = object_tree(objflags)->rb_node; unsigned long untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr); while (rb) { struct kmemleak_object *object; unsigned long untagged_objp; object = rb_entry(rb, struct kmemleak_object, rb_node); untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer); if (untagged_ptr < untagged_objp) rb = object->rb_node.rb_left; else if (untagged_objp + object->size <= untagged_ptr) rb = object->rb_node.rb_right; else if (untagged_objp == untagged_ptr || alias) return object; else { kmemleak_warn("Found object by alias at 0x%08lx\n", ptr); dump_object_info(object); break; } } return NULL; } /* Look-up a kmemleak object which allocated with virtual address. */ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias) { return __lookup_object(ptr, alias, 0); } /* * Increment the object use_count. Return 1 if successful or 0 otherwise. Note * that once an object's use_count reached 0, the RCU freeing was already * registered and the object should no longer be used. This function must be * called under the protection of rcu_read_lock(). */ static int get_object(struct kmemleak_object *object) { return atomic_inc_not_zero(&object->use_count); } /* * Memory pool allocation and freeing. kmemleak_lock must not be held. */ static struct kmemleak_object *mem_pool_alloc(gfp_t gfp) { unsigned long flags; struct kmemleak_object *object; /* try the slab allocator first */ if (object_cache) { object = kmem_cache_alloc_noprof(object_cache, gfp_nested_mask(gfp)); if (object) return object; } /* slab allocation failed, try the memory pool */ raw_spin_lock_irqsave(&kmemleak_lock, flags); object = list_first_entry_or_null(&mem_pool_free_list, typeof(*object), object_list); if (object) list_del(&object->object_list); else if (mem_pool_free_count) object = &mem_pool[--mem_pool_free_count]; else pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n"); raw_spin_unlock_irqrestore(&kmemleak_lock, flags); return object; } /* * Return the object to either the slab allocator or the memory pool. */ static void mem_pool_free(struct kmemleak_object *object) { unsigned long flags; if (object < mem_pool || object >= mem_pool + ARRAY_SIZE(mem_pool)) { kmem_cache_free(object_cache, object); return; } /* add the object to the memory pool free list */ raw_spin_lock_irqsave(&kmemleak_lock, flags); list_add(&object->object_list, &mem_pool_free_list); raw_spin_unlock_irqrestore(&kmemleak_lock, flags); } /* * RCU callback to free a kmemleak_object. */ static void free_object_rcu(struct rcu_head *rcu) { struct hlist_node *tmp; struct kmemleak_scan_area *area; struct kmemleak_object *object = container_of(rcu, struct kmemleak_object, rcu); /* * Once use_count is 0 (guaranteed by put_object), there is no other * code accessing this object, hence no need for locking. */ hlist_for_each_entry_safe(area, tmp, &object->area_list, node) { hlist_del(&area->node); kmem_cache_free(scan_area_cache, area); } mem_pool_free(object); } /* * Decrement the object use_count. Once the count is 0, free the object using * an RCU callback. Since put_object() may be called via the kmemleak_free() -> * delete_object() path, the delayed RCU freeing ensures that there is no * recursive call to the kernel allocator. Lock-less RCU object_list traversal * is also possible. */ static void put_object(struct kmemleak_object *object) { if (!atomic_dec_and_test(&object->use_count)) return; /* should only get here after delete_object was called */ WARN_ON(object->flags & OBJECT_ALLOCATED); /* * It may be too early for the RCU callbacks, however, there is no * concurrent object_list traversal when !object_cache and all objects * came from the memory pool. Free the object directly. */ if (object_cache) call_rcu(&object->rcu, free_object_rcu); else free_object_rcu(&object->rcu); } /* * Look up an object in the object search tree and increase its use_count. */ static struct kmemleak_object *__find_and_get_object(unsigned long ptr, int alias, unsigned int objflags) { unsigned long flags; struct kmemleak_object *object; rcu_read_lock(); raw_spin_lock_irqsave(&kmemleak_lock, flags); object = __lookup_object(ptr, alias, objflags); raw_spin_unlock_irqrestore(&kmemleak_lock, flags); /* check whether the object is still available */ if (object && !get_object(object)) object = NULL; rcu_read_unlock(); return object; } /* Look up and get an object which allocated with virtual address. */ static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias) { return __find_and_get_object(ptr, alias, 0); } /* * Remove an object from its object tree and object_list. Must be called with * the kmemleak_lock held _if_ kmemleak is still enabled. */ static void __remove_object(struct kmemleak_object *object) { rb_erase(&object->rb_node, object_tree(object->flags)); if (!(object->del_state & DELSTATE_NO_DELETE)) list_del_rcu(&object->object_list); object->del_state |= DELSTATE_REMOVED; } static struct kmemleak_object *__find_and_remove_object(unsigned long ptr, int alias, unsigned int objflags) { struct kmemleak_object *object; object = __lookup_object(ptr, alias, objflags); if (object) __remove_object(object); return object; } /* * Look up an object in the object search tree and remove it from both object * tree root and object_list. The returned object's use_count should be at * least 1, as initially set by create_object(). */ static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias, unsigned int objflags) { unsigned long flags; struct kmemleak_object *object; raw_spin_lock_irqsave(&kmemleak_lock, flags); object = __find_and_remove_object(ptr, alias, objflags); raw_spin_unlock_irqrestore(&kmemleak_lock, flags); return object; } static noinline depot_stack_handle_t set_track_prepare(void) { depot_stack_handle_t trace_handle; unsigned long entries[MAX_TRACE]; unsigned int nr_entries; /* * Use object_cache to determine whether kmemleak_init() has * been invoked. stack_depot_early_init() is called before * kmemleak_init() in mm_core_init(). */ if (!object_cache) return 0; nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3); trace_handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT); return trace_handle; } static struct kmemleak_object *__alloc_object(gfp_t gfp) { struct kmemleak_object *object; object = mem_pool_alloc(gfp); if (!object) { pr_warn("Cannot allocate a kmemleak_object structure\n"); kmemleak_disable(); return NULL; } INIT_LIST_HEAD(&object->object_list); INIT_LIST_HEAD(&object->gray_list); INIT_HLIST_HEAD(&object->area_list); raw_spin_lock_init(&object->lock); atomic_set(&object->use_count, 1); object->excess_ref = 0; object->count = 0; /* white color initially */ object->checksum = 0; object->del_state = 0; /* task information */ if (in_hardirq()) { object->pid = 0; strscpy(object->comm, "hardirq"); } else if (in_serving_softirq()) { object->pid = 0; strscpy(object->comm, "softirq"); } else { object->pid = current->pid; /* * There is a small chance of a race with set_task_comm(), * however using get_task_comm() here may cause locking * dependency issues with current->alloc_lock. In the worst * case, the command line is not correct. */ strscpy(object->comm, current->comm); } /* kernel backtrace */ object->trace_handle = set_track_prepare(); return object; } static int __link_object(struct kmemleak_object *object, unsigned long ptr, size_t size, int min_count, unsigned int objflags) { struct kmemleak_object *parent; struct rb_node **link, *rb_parent; unsigned long untagged_ptr; unsigned long untagged_objp; object->flags = OBJECT_ALLOCATED | objflags; object->pointer = ptr; object->size = kfence_ksize((void *)ptr) ?: size; object->min_count = min_count; object->jiffies = jiffies; untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr); /* * Only update min_addr and max_addr with object * storing virtual address. */ if (!(objflags & (OBJECT_PHYS | OBJECT_PERCPU))) { min_addr = min(min_addr, untagged_ptr); max_addr = max(max_addr, untagged_ptr + size); } link = &object_tree(objflags)->rb_node; rb_parent = NULL; while (*link) { rb_parent = *link; parent = rb_entry(rb_parent, struct kmemleak_object, rb_node); untagged_objp = (unsigned long)kasan_reset_tag((void *)parent->pointer); if (untagged_ptr + size <= untagged_objp) link = &parent->rb_node.rb_left; else if (untagged_objp + parent->size <= untagged_ptr) link = &parent->rb_node.rb_right; else { kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n", ptr); /* * No need for parent->lock here since "parent" cannot * be freed while the kmemleak_lock is held. */ dump_object_info(parent); return -EEXIST; } } rb_link_node(&object->rb_node, rb_parent, link); rb_insert_color(&object->rb_node, object_tree(objflags)); list_add_tail_rcu(&object->object_list, &object_list); return 0; } /* * Create the metadata (struct kmemleak_object) corresponding to an allocated * memory block and add it to the object_list and object tree. */ static void __create_object(unsigned long ptr, size_t size, int min_count, gfp_t gfp, unsigned int objflags) { struct kmemleak_object *object; unsigned long flags; int ret; object = __alloc_object(gfp); if (!object) return; raw_spin_lock_irqsave(&kmemleak_lock, flags); ret = __link_object(object, ptr, size, min_count, objflags); raw_spin_unlock_irqrestore(&kmemleak_lock, flags); if (ret) mem_pool_free(object); } /* Create kmemleak object which allocated with virtual address. */ static void create_object(unsigned long ptr, size_t size, int min_count, gfp_t gfp) { __create_object(ptr, size, min_count, gfp, 0); } /* Create kmemleak object which allocated with physical address. */ static void create_object_phys(unsigned long ptr, size_t size, int min_count, gfp_t gfp) { __create_object(ptr, size, min_count, gfp, OBJECT_PHYS); } /* Create kmemleak object corresponding to a per-CPU allocation. */ static void create_object_percpu(unsigned long ptr, size_t size, int min_count, gfp_t gfp) { __create_object(ptr, size, min_count, gfp, OBJECT_PERCPU); } /* * Mark the object as not allocated and schedule RCU freeing via put_object(). */ static void __delete_object(struct kmemleak_object *object) { unsigned long flags; WARN_ON(!(object->flags & OBJECT_ALLOCATED)); WARN_ON(atomic_read(&object->use_count) < 1); /* * Locking here also ensures that the corresponding memory block * cannot be freed when it is being scanned. */ raw_spin_lock_irqsave(&object->lock, flags); object->flags &= ~OBJECT_ALLOCATED; raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } /* * Look up the metadata (struct kmemleak_object) corresponding to ptr and * delete it. */ static void delete_object_full(unsigned long ptr, unsigned int objflags) { struct kmemleak_object *object; object = find_and_remove_object(ptr, 0, objflags); if (!object) { #ifdef DEBUG kmemleak_warn("Freeing unknown object at 0x%08lx\n", ptr); #endif return; } __delete_object(object); } /* * Look up the metadata (struct kmemleak_object) corresponding to ptr and * delete it. If the memory block is partially freed, the function may create * additional metadata for the remaining parts of the block. */ static void delete_object_part(unsigned long ptr, size_t size, unsigned int objflags) { struct kmemleak_object *object, *object_l, *object_r; unsigned long start, end, flags; object_l = __alloc_object(GFP_KERNEL); if (!object_l) return; object_r = __alloc_object(GFP_KERNEL); if (!object_r) goto out; raw_spin_lock_irqsave(&kmemleak_lock, flags); object = __find_and_remove_object(ptr, 1, objflags); if (!object) { #ifdef DEBUG kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n", ptr, size); #endif goto unlock; } /* * Create one or two objects that may result from the memory block * split. Note that partial freeing is only done by free_bootmem() and * this happens before kmemleak_init() is called. */ start = object->pointer; end = object->pointer + object->size; if ((ptr > start) && !__link_object(object_l, start, ptr - start, object->min_count, objflags)) object_l = NULL; if ((ptr + size < end) && !__link_object(object_r, ptr + size, end - ptr - size, object->min_count, objflags)) object_r = NULL; unlock: raw_spin_unlock_irqrestore(&kmemleak_lock, flags); if (object) __delete_object(object); out: if (object_l) mem_pool_free(object_l); if (object_r) mem_pool_free(object_r); } static void __paint_it(struct kmemleak_object *object, int color) { object->min_count = color; if (color == KMEMLEAK_BLACK) object->flags |= OBJECT_NO_SCAN; } static void paint_it(struct kmemleak_object *object, int color) { unsigned long flags; raw_spin_lock_irqsave(&object->lock, flags); __paint_it(object, color); raw_spin_unlock_irqrestore(&object->lock, flags); } static void paint_ptr(unsigned long ptr, int color, unsigned int objflags) { struct kmemleak_object *object; object = __find_and_get_object(ptr, 0, objflags); if (!object) { kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n", ptr, (color == KMEMLEAK_GREY) ? "Grey" : (color == KMEMLEAK_BLACK) ? "Black" : "Unknown"); return; } paint_it(object, color); put_object(object); } /* * Mark an object permanently as gray-colored so that it can no longer be * reported as a leak. This is used in general to mark a false positive. */ static void make_gray_object(unsigned long ptr) { paint_ptr(ptr, KMEMLEAK_GREY, 0); } /* * Mark the object as black-colored so that it is ignored from scans and * reporting. */ static void make_black_object(unsigned long ptr, unsigned int objflags) { paint_ptr(ptr, KMEMLEAK_BLACK, objflags); } /* * Add a scanning area to the object. If at least one such area is added, * kmemleak will only scan these ranges rather than the whole memory block. */ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp) { unsigned long flags; struct kmemleak_object *object; struct kmemleak_scan_area *area = NULL; unsigned long untagged_ptr; unsigned long untagged_objp; object = find_and_get_object(ptr, 1); if (!object) { kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n", ptr); return; } untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr); untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer); if (scan_area_cache) area = kmem_cache_alloc_noprof(scan_area_cache, gfp_nested_mask(gfp)); raw_spin_lock_irqsave(&object->lock, flags); if (!area) { pr_warn_once("Cannot allocate a scan area, scanning the full object\n"); /* mark the object for full scan to avoid false positives */ object->flags |= OBJECT_FULL_SCAN; goto out_unlock; } if (size == SIZE_MAX) { size = untagged_objp + object->size - untagged_ptr; } else if (untagged_ptr + size > untagged_objp + object->size) { kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr); dump_object_info(object); kmem_cache_free(scan_area_cache, area); goto out_unlock; } INIT_HLIST_NODE(&area->node); area->start = ptr; area->size = size; hlist_add_head(&area->node, &object->area_list); out_unlock: raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } /* * Any surplus references (object already gray) to 'ptr' are passed to * 'excess_ref'. This is used in the vmalloc() case where a pointer to * vm_struct may be used as an alternative reference to the vmalloc'ed object * (see free_thread_stack()). */ static void object_set_excess_ref(unsigned long ptr, unsigned long excess_ref) { unsigned long flags; struct kmemleak_object *object; object = find_and_get_object(ptr, 0); if (!object) { kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n", ptr); return; } raw_spin_lock_irqsave(&object->lock, flags); object->excess_ref = excess_ref; raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } /* * Set the OBJECT_NO_SCAN flag for the object corresponding to the give * pointer. Such object will not be scanned by kmemleak but references to it * are searched. */ static void object_no_scan(unsigned long ptr) { unsigned long flags; struct kmemleak_object *object; object = find_and_get_object(ptr, 0); if (!object) { kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr); return; } raw_spin_lock_irqsave(&object->lock, flags); object->flags |= OBJECT_NO_SCAN; raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } /** * kmemleak_alloc - register a newly allocated object * @ptr: pointer to beginning of the object * @size: size of the object * @min_count: minimum number of references to this object. If during memory * scanning a number of references less than @min_count is found, * the object is reported as a memory leak. If @min_count is 0, * the object is never reported as a leak. If @min_count is -1, * the object is ignored (not scanned and not reported as a leak) * @gfp: kmalloc() flags used for kmemleak internal memory allocations * * This function is called from the kernel allocators when a new object * (memory block) is allocated (kmem_cache_alloc, kmalloc etc.). */ void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count, gfp_t gfp) { pr_debug("%s(0x%px, %zu, %d)\n", __func__, ptr, size, min_count); if (kmemleak_enabled && ptr && !IS_ERR(ptr)) create_object((unsigned long)ptr, size, min_count, gfp); } EXPORT_SYMBOL_GPL(kmemleak_alloc); /** * kmemleak_alloc_percpu - register a newly allocated __percpu object * @ptr: __percpu pointer to beginning of the object * @size: size of the object * @gfp: flags used for kmemleak internal memory allocations * * This function is called from the kernel percpu allocator when a new object * (memory block) is allocated (alloc_percpu). */ void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size, gfp_t gfp) { pr_debug("%s(0x%px, %zu)\n", __func__, ptr, size); /* * Percpu allocations are only scanned and not reported as leaks * (min_count is set to 0). */ if (kmemleak_enabled && ptr && !IS_ERR(ptr)) create_object_percpu((unsigned long)ptr, size, 0, gfp); } EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu); /** * kmemleak_vmalloc - register a newly vmalloc'ed object * @area: pointer to vm_struct * @size: size of the object * @gfp: __vmalloc() flags used for kmemleak internal memory allocations * * This function is called from the vmalloc() kernel allocator when a new * object (memory block) is allocated. */ void __ref kmemleak_vmalloc(const struct vm_struct *area, size_t size, gfp_t gfp) { pr_debug("%s(0x%px, %zu)\n", __func__, area, size); /* * A min_count = 2 is needed because vm_struct contains a reference to * the virtual address of the vmalloc'ed block. */ if (kmemleak_enabled) { create_object((unsigned long)area->addr, size, 2, gfp); object_set_excess_ref((unsigned long)area, (unsigned long)area->addr); } } EXPORT_SYMBOL_GPL(kmemleak_vmalloc); /** * kmemleak_free - unregister a previously registered object * @ptr: pointer to beginning of the object * * This function is called from the kernel allocators when an object (memory * block) is freed (kmem_cache_free, kfree, vfree etc.). */ void __ref kmemleak_free(const void *ptr) { pr_debug("%s(0x%px)\n", __func__, ptr); if (kmemleak_free_enabled && ptr && !IS_ERR(ptr)) delete_object_full((unsigned long)ptr, 0); } EXPORT_SYMBOL_GPL(kmemleak_free); /** * kmemleak_free_part - partially unregister a previously registered object * @ptr: pointer to the beginning or inside the object. This also * represents the start of the range to be freed * @size: size to be unregistered * * This function is called when only a part of a memory block is freed * (usually from the bootmem allocator). */ void __ref kmemleak_free_part(const void *ptr, size_t size) { pr_debug("%s(0x%px)\n", __func__, ptr); if (kmemleak_enabled && ptr && !IS_ERR(ptr)) delete_object_part((unsigned long)ptr, size, 0); } EXPORT_SYMBOL_GPL(kmemleak_free_part); /** * kmemleak_free_percpu - unregister a previously registered __percpu object * @ptr: __percpu pointer to beginning of the object * * This function is called from the kernel percpu allocator when an object * (memory block) is freed (free_percpu). */ void __ref kmemleak_free_percpu(const void __percpu *ptr) { pr_debug("%s(0x%px)\n", __func__, ptr); if (kmemleak_free_enabled && ptr && !IS_ERR(ptr)) delete_object_full((unsigned long)ptr, OBJECT_PERCPU); } EXPORT_SYMBOL_GPL(kmemleak_free_percpu); /** * kmemleak_update_trace - update object allocation stack trace * @ptr: pointer to beginning of the object * * Override the object allocation stack trace for cases where the actual * allocation place is not always useful. */ void __ref kmemleak_update_trace(const void *ptr) { struct kmemleak_object *object; depot_stack_handle_t trace_handle; unsigned long flags; pr_debug("%s(0x%px)\n", __func__, ptr); if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr)) return; object = find_and_get_object((unsigned long)ptr, 1); if (!object) { #ifdef DEBUG kmemleak_warn("Updating stack trace for unknown object at %p\n", ptr); #endif return; } trace_handle = set_track_prepare(); raw_spin_lock_irqsave(&object->lock, flags); object->trace_handle = trace_handle; raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); } EXPORT_SYMBOL(kmemleak_update_trace); /** * kmemleak_not_leak - mark an allocated object as false positive * @ptr: pointer to beginning of the object * * Calling this function on an object will cause the memory block to no longer * be reported as leak and always be scanned. */ void __ref kmemleak_not_leak(const void *ptr) { pr_debug("%s(0x%px)\n", __func__, ptr); if (kmemleak_enabled && ptr && !IS_ERR(ptr)) make_gray_object((unsigned long)ptr); } EXPORT_SYMBOL(kmemleak_not_leak); /** * kmemleak_ignore - ignore an allocated object * @ptr: pointer to beginning of the object * * Calling this function on an object will cause the memory block to be * ignored (not scanned and not reported as a leak). This is usually done when * it is known that the corresponding block is not a leak and does not contain * any references to other allocated memory blocks. */ void __ref kmemleak_ignore(const void *ptr) { pr_debug("%s(0x%px)\n", __func__, ptr); if (kmemleak_enabled && ptr && !IS_ERR(ptr)) make_black_object((unsigned long)ptr, 0); } EXPORT_SYMBOL(kmemleak_ignore); /** * kmemleak_scan_area - limit the range to be scanned in an allocated object * @ptr: pointer to beginning or inside the object. This also * represents the start of the scan area * @size: size of the scan area * @gfp: kmalloc() flags used for kmemleak internal memory allocations * * This function is used when it is known that only certain parts of an object * contain references to other objects. Kmemleak will only scan these areas * reducing the number false negatives. */ void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp) { pr_debug("%s(0x%px)\n", __func__, ptr); if (kmemleak_enabled && ptr && size && !IS_ERR(ptr)) add_scan_area((unsigned long)ptr, size, gfp); } EXPORT_SYMBOL(kmemleak_scan_area); /** * kmemleak_no_scan - do not scan an allocated object * @ptr: pointer to beginning of the object * * This function notifies kmemleak not to scan the given memory block. Useful * in situations where it is known that the given object does not contain any * references to other objects. Kmemleak will not scan such objects reducing * the number of false negatives. */ void __ref kmemleak_no_scan(const void *ptr) { pr_debug("%s(0x%px)\n", __func__, ptr); if (kmemleak_enabled && ptr && !IS_ERR(ptr)) object_no_scan((unsigned long)ptr); } EXPORT_SYMBOL(kmemleak_no_scan); /** * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical * address argument * @phys: physical address of the object * @size: size of the object * @gfp: kmalloc() flags used for kmemleak internal memory allocations */ void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, gfp_t gfp) { pr_debug("%s(0x%px, %zu)\n", __func__, &phys, size); if (kmemleak_enabled) /* * Create object with OBJECT_PHYS flag and * assume min_count 0. */ create_object_phys((unsigned long)phys, size, 0, gfp); } EXPORT_SYMBOL(kmemleak_alloc_phys); /** * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a * physical address argument * @phys: physical address if the beginning or inside an object. This * also represents the start of the range to be freed * @size: size to be unregistered */ void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size) { pr_debug("%s(0x%px)\n", __func__, &phys); if (kmemleak_enabled) delete_object_part((unsigned long)phys, size, OBJECT_PHYS); } EXPORT_SYMBOL(kmemleak_free_part_phys); /** * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical * address argument * @phys: physical address of the object */ void __ref kmemleak_ignore_phys(phys_addr_t phys) { pr_debug("%s(0x%px)\n", __func__, &phys); if (kmemleak_enabled) make_black_object((unsigned long)phys, OBJECT_PHYS); } EXPORT_SYMBOL(kmemleak_ignore_phys); /* * Update an object's checksum and return true if it was modified. */ static bool update_checksum(struct kmemleak_object *object) { u32 old_csum = object->checksum; if (WARN_ON_ONCE(object->flags & (OBJECT_PHYS | OBJECT_PERCPU))) return false; kasan_disable_current(); kcsan_disable_current(); object->checksum = crc32(0, kasan_reset_tag((void *)object->pointer), object->size); kasan_enable_current(); kcsan_enable_current(); return object->checksum != old_csum; } /* * Update an object's references. object->lock must be held by the caller. */ static void update_refs(struct kmemleak_object *object) { if (!color_white(object)) { /* non-orphan, ignored or new */ return; } /* * Increase the object's reference count (number of pointers to the * memory block). If this count reaches the required minimum, the * object's color will become gray and it will be added to the * gray_list. */ object->count++; if (color_gray(object)) { /* put_object() called when removing from gray_list */ WARN_ON(!get_object(object)); list_add_tail(&object->gray_list, &gray_list); } } /* * Memory scanning is a long process and it needs to be interruptible. This * function checks whether such interrupt condition occurred. */ static int scan_should_stop(void) { if (!kmemleak_enabled) return 1; /* * This function may be called from either process or kthread context, * hence the need to check for both stop conditions. */ if (current->mm) return signal_pending(current); else return kthread_should_stop(); return 0; } /* * Scan a memory block (exclusive range) for valid pointers and add those * found to the gray list. */ static void scan_block(void *_start, void *_end, struct kmemleak_object *scanned) { unsigned long *ptr; unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER); unsigned long *end = _end - (BYTES_PER_POINTER - 1); unsigned long flags; unsigned long untagged_ptr; raw_spin_lock_irqsave(&kmemleak_lock, flags); for (ptr = start; ptr < end; ptr++) { struct kmemleak_object *object; unsigned long pointer; unsigned long excess_ref; if (scan_should_stop()) break; kasan_disable_current(); pointer = *(unsigned long *)kasan_reset_tag((void *)ptr); kasan_enable_current(); untagged_ptr = (unsigned long)kasan_reset_tag((void *)pointer); if (untagged_ptr < min_addr || untagged_ptr >= max_addr) continue; /* * No need for get_object() here since we hold kmemleak_lock. * object->use_count cannot be dropped to 0 while the object * is still present in object_tree_root and object_list * (with updates protected by kmemleak_lock). */ object = lookup_object(pointer, 1); if (!object) continue; if (object == scanned) /* self referenced, ignore */ continue; /* * Avoid the lockdep recursive warning on object->lock being * previously acquired in scan_object(). These locks are * enclosed by scan_mutex. */ raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING); /* only pass surplus references (object already gray) */ if (color_gray(object)) { excess_ref = object->excess_ref; /* no need for update_refs() if object already gray */ } else { excess_ref = 0; update_refs(object); } raw_spin_unlock(&object->lock); if (excess_ref) { object = lookup_object(excess_ref, 0); if (!object) continue; if (object == scanned) /* circular reference, ignore */ continue; raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING); update_refs(object); raw_spin_unlock(&object->lock); } } raw_spin_unlock_irqrestore(&kmemleak_lock, flags); } /* * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency. */ #ifdef CONFIG_SMP static void scan_large_block(void *start, void *end) { void *next; while (start < end) { next = min(start + MAX_SCAN_SIZE, end); scan_block(start, next, NULL); start = next; cond_resched(); } } #endif /* * Scan a memory block corresponding to a kmemleak_object. A condition is * that object->use_count >= 1. */ static void scan_object(struct kmemleak_object *object) { struct kmemleak_scan_area *area; unsigned long flags; /* * Once the object->lock is acquired, the corresponding memory block * cannot be freed (the same lock is acquired in delete_object). */ raw_spin_lock_irqsave(&object->lock, flags); if (object->flags & OBJECT_NO_SCAN) goto out; if (!(object->flags & OBJECT_ALLOCATED)) /* already freed object */ goto out; if (object->flags & OBJECT_PERCPU) { unsigned int cpu; for_each_possible_cpu(cpu) { void *start = per_cpu_ptr((void __percpu *)object->pointer, cpu); void *end = start + object->size; scan_block(start, end, object); raw_spin_unlock_irqrestore(&object->lock, flags); cond_resched(); raw_spin_lock_irqsave(&object->lock, flags); if (!(object->flags & OBJECT_ALLOCATED)) break; } } else if (hlist_empty(&object->area_list) || object->flags & OBJECT_FULL_SCAN) { void *start = object->flags & OBJECT_PHYS ? __va((phys_addr_t)object->pointer) : (void *)object->pointer; void *end = start + object->size; void *next; do { next = min(start + MAX_SCAN_SIZE, end); scan_block(start, next, object); start = next; if (start >= end) break; raw_spin_unlock_irqrestore(&object->lock, flags); cond_resched(); raw_spin_lock_irqsave(&object->lock, flags); } while (object->flags & OBJECT_ALLOCATED); } else { hlist_for_each_entry(area, &object->area_list, node) scan_block((void *)area->start, (void *)(area->start + area->size), object); } out: raw_spin_unlock_irqrestore(&object->lock, flags); } /* * Scan the objects already referenced (gray objects). More objects will be * referenced and, if there are no memory leaks, all the objects are scanned. */ static void scan_gray_list(void) { struct kmemleak_object *object, *tmp; /* * The list traversal is safe for both tail additions and removals * from inside the loop. The kmemleak objects cannot be freed from * outside the loop because their use_count was incremented. */ object = list_entry(gray_list.next, typeof(*object), gray_list); while (&object->gray_list != &gray_list) { cond_resched(); /* may add new objects to the list */ if (!scan_should_stop()) scan_object(object); tmp = list_entry(object->gray_list.next, typeof(*object), gray_list); /* remove the object from the list and release it */ list_del(&object->gray_list); put_object(object); object = tmp; } WARN_ON(!list_empty(&gray_list)); } /* * Conditionally call resched() in an object iteration loop while making sure * that the given object won't go away without RCU read lock by performing a * get_object() if necessaary. */ static void kmemleak_cond_resched(struct kmemleak_object *object) { if (!get_object(object)) return; /* Try next object */ raw_spin_lock_irq(&kmemleak_lock); if (object->del_state & DELSTATE_REMOVED) goto unlock_put; /* Object removed */ object->del_state |= DELSTATE_NO_DELETE; raw_spin_unlock_irq(&kmemleak_lock); rcu_read_unlock(); cond_resched(); rcu_read_lock(); raw_spin_lock_irq(&kmemleak_lock); if (object->del_state & DELSTATE_REMOVED) list_del_rcu(&object->object_list); object->del_state &= ~DELSTATE_NO_DELETE; unlock_put: raw_spin_unlock_irq(&kmemleak_lock); put_object(object); } /* * Scan data sections and all the referenced memory blocks allocated via the * kernel's standard allocators. This function must be called with the * scan_mutex held. */ static void kmemleak_scan(void) { struct kmemleak_object *object; struct zone *zone; int __maybe_unused i; int new_leaks = 0; jiffies_last_scan = jiffies; /* prepare the kmemleak_object's */ rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { raw_spin_lock_irq(&object->lock); #ifdef DEBUG /* * With a few exceptions there should be a maximum of * 1 reference to any object at this point. */ if (atomic_read(&object->use_count) > 1) { pr_debug("object->use_count = %d\n", atomic_read(&object->use_count)); dump_object_info(object); } #endif /* ignore objects outside lowmem (paint them black) */ if ((object->flags & OBJECT_PHYS) && !(object->flags & OBJECT_NO_SCAN)) { unsigned long phys = object->pointer; if (PHYS_PFN(phys) < min_low_pfn || PHYS_PFN(phys + object->size) >= max_low_pfn) __paint_it(object, KMEMLEAK_BLACK); } /* reset the reference count (whiten the object) */ object->count = 0; if (color_gray(object) && get_object(object)) list_add_tail(&object->gray_list, &gray_list); raw_spin_unlock_irq(&object->lock); if (need_resched()) kmemleak_cond_resched(object); } rcu_read_unlock(); #ifdef CONFIG_SMP /* per-cpu sections scanning */ for_each_possible_cpu(i) scan_large_block(__per_cpu_start + per_cpu_offset(i), __per_cpu_end + per_cpu_offset(i)); #endif /* * Struct page scanning for each node. */ get_online_mems(); for_each_populated_zone(zone) { unsigned long start_pfn = zone->zone_start_pfn; unsigned long end_pfn = zone_end_pfn(zone); unsigned long pfn; for (pfn = start_pfn; pfn < end_pfn; pfn++) { struct page *page = pfn_to_online_page(pfn); if (!(pfn & 63)) cond_resched(); if (!page) continue; /* only scan pages belonging to this zone */ if (page_zone(page) != zone) continue; /* only scan if page is in use */ if (page_count(page) == 0) continue; scan_block(page, page + 1, NULL); } } put_online_mems(); /* * Scanning the task stacks (may introduce false negatives). */ if (kmemleak_stack_scan) { struct task_struct *p, *g; rcu_read_lock(); for_each_process_thread(g, p) { void *stack = try_get_task_stack(p); if (stack) { scan_block(stack, stack + THREAD_SIZE, NULL); put_task_stack(p); } } rcu_read_unlock(); } /* * Scan the objects already referenced from the sections scanned * above. */ scan_gray_list(); /* * Check for new or unreferenced objects modified since the previous * scan and color them gray until the next scan. */ rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { if (need_resched()) kmemleak_cond_resched(object); /* * This is racy but we can save the overhead of lock/unlock * calls. The missed objects, if any, should be caught in * the next scan. */ if (!color_white(object)) continue; raw_spin_lock_irq(&object->lock); if (color_white(object) && (object->flags & OBJECT_ALLOCATED) && update_checksum(object) && get_object(object)) { /* color it gray temporarily */ object->count = object->min_count; list_add_tail(&object->gray_list, &gray_list); } raw_spin_unlock_irq(&object->lock); } rcu_read_unlock(); /* * Re-scan the gray list for modified unreferenced objects. */ scan_gray_list(); /* * If scanning was stopped do not report any new unreferenced objects. */ if (scan_should_stop()) return; /* * Scanning result reporting. */ rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { if (need_resched()) kmemleak_cond_resched(object); /* * This is racy but we can save the overhead of lock/unlock * calls. The missed objects, if any, should be caught in * the next scan. */ if (!color_white(object)) continue; raw_spin_lock_irq(&object->lock); if (unreferenced_object(object) && !(object->flags & OBJECT_REPORTED)) { object->flags |= OBJECT_REPORTED; if (kmemleak_verbose) print_unreferenced(NULL, object); new_leaks++; } raw_spin_unlock_irq(&object->lock); } rcu_read_unlock(); if (new_leaks) { kmemleak_found_leaks = true; pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n", new_leaks); } } /* * Thread function performing automatic memory scanning. Unreferenced objects * at the end of a memory scan are reported but only the first time. */ static int kmemleak_scan_thread(void *arg) { static int first_run = IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN); pr_info("Automatic memory scanning thread started\n"); set_user_nice(current, 10); /* * Wait before the first scan to allow the system to fully initialize. */ if (first_run) { signed long timeout = msecs_to_jiffies(SECS_FIRST_SCAN * 1000); first_run = 0; while (timeout && !kthread_should_stop()) timeout = schedule_timeout_interruptible(timeout); } while (!kthread_should_stop()) { signed long timeout = READ_ONCE(jiffies_scan_wait); mutex_lock(&scan_mutex); kmemleak_scan(); mutex_unlock(&scan_mutex); /* wait before the next scan */ while (timeout && !kthread_should_stop()) timeout = schedule_timeout_interruptible(timeout); } pr_info("Automatic memory scanning thread ended\n"); return 0; } /* * Start the automatic memory scanning thread. This function must be called * with the scan_mutex held. */ static void start_scan_thread(void) { if (scan_thread) return; scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak"); if (IS_ERR(scan_thread)) { pr_warn("Failed to create the scan thread\n"); scan_thread = NULL; } } /* * Stop the automatic memory scanning thread. */ static void stop_scan_thread(void) { if (scan_thread) { kthread_stop(scan_thread); scan_thread = NULL; } } /* * Iterate over the object_list and return the first valid object at or after * the required position with its use_count incremented. The function triggers * a memory scanning when the pos argument points to the first position. */ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos) { struct kmemleak_object *object; loff_t n = *pos; int err; err = mutex_lock_interruptible(&scan_mutex); if (err < 0) return ERR_PTR(err); rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { if (n-- > 0) continue; if (get_object(object)) goto out; } object = NULL; out: return object; } /* * Return the next object in the object_list. The function decrements the * use_count of the previous object and increases that of the next one. */ static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos) { struct kmemleak_object *prev_obj = v; struct kmemleak_object *next_obj = NULL; struct kmemleak_object *obj = prev_obj; ++(*pos); list_for_each_entry_continue_rcu(obj, &object_list, object_list) { if (get_object(obj)) { next_obj = obj; break; } } put_object(prev_obj); return next_obj; } /* * Decrement the use_count of the last object required, if any. */ static void kmemleak_seq_stop(struct seq_file *seq, void *v) { if (!IS_ERR(v)) { /* * kmemleak_seq_start may return ERR_PTR if the scan_mutex * waiting was interrupted, so only release it if !IS_ERR. */ rcu_read_unlock(); mutex_unlock(&scan_mutex); if (v) put_object(v); } } /* * Print the information for an unreferenced object to the seq file. */ static int kmemleak_seq_show(struct seq_file *seq, void *v) { struct kmemleak_object *object = v; unsigned long flags; raw_spin_lock_irqsave(&object->lock, flags); if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) print_unreferenced(seq, object); raw_spin_unlock_irqrestore(&object->lock, flags); return 0; } static const struct seq_operations kmemleak_seq_ops = { .start = kmemleak_seq_start, .next = kmemleak_seq_next, .stop = kmemleak_seq_stop, .show = kmemleak_seq_show, }; static int kmemleak_open(struct inode *inode, struct file *file) { return seq_open(file, &kmemleak_seq_ops); } static int dump_str_object_info(const char *str) { unsigned long flags; struct kmemleak_object *object; unsigned long addr; if (kstrtoul(str, 0, &addr)) return -EINVAL; object = find_and_get_object(addr, 0); if (!object) { pr_info("Unknown object at 0x%08lx\n", addr); return -EINVAL; } raw_spin_lock_irqsave(&object->lock, flags); dump_object_info(object); raw_spin_unlock_irqrestore(&object->lock, flags); put_object(object); return 0; } /* * We use grey instead of black to ensure we can do future scans on the same * objects. If we did not do future scans these black objects could * potentially contain references to newly allocated objects in the future and * we'd end up with false positives. */ static void kmemleak_clear(void) { struct kmemleak_object *object; rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { raw_spin_lock_irq(&object->lock); if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) __paint_it(object, KMEMLEAK_GREY); raw_spin_unlock_irq(&object->lock); } rcu_read_unlock(); kmemleak_found_leaks = false; } static void __kmemleak_do_cleanup(void); /* * File write operation to configure kmemleak at run-time. The following * commands can be written to the /sys/kernel/debug/kmemleak file: * off - disable kmemleak (irreversible) * stack=on - enable the task stacks scanning * stack=off - disable the tasks stacks scanning * scan=on - start the automatic memory scanning thread * scan=off - stop the automatic memory scanning thread * scan=... - set the automatic memory scanning period in seconds (0 to * disable it) * scan - trigger a memory scan * clear - mark all current reported unreferenced kmemleak objects as * grey to ignore printing them, or free all kmemleak objects * if kmemleak has been disabled. * dump=... - dump information about the object found at the given address */ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf, size_t size, loff_t *ppos) { char buf[64]; int buf_size; int ret; buf_size = min(size, (sizeof(buf) - 1)); if (strncpy_from_user(buf, user_buf, buf_size) < 0) return -EFAULT; buf[buf_size] = 0; ret = mutex_lock_interruptible(&scan_mutex); if (ret < 0) return ret; if (strncmp(buf, "clear", 5) == 0) { if (kmemleak_enabled) kmemleak_clear(); else __kmemleak_do_cleanup(); goto out; } if (!kmemleak_enabled) { ret = -EPERM; goto out; } if (strncmp(buf, "off", 3) == 0) kmemleak_disable(); else if (strncmp(buf, "stack=on", 8) == 0) kmemleak_stack_scan = 1; else if (strncmp(buf, "stack=off", 9) == 0) kmemleak_stack_scan = 0; else if (strncmp(buf, "scan=on", 7) == 0) start_scan_thread(); else if (strncmp(buf, "scan=off", 8) == 0) stop_scan_thread(); else if (strncmp(buf, "scan=", 5) == 0) { unsigned secs; unsigned long msecs; ret = kstrtouint(buf + 5, 0, &secs); if (ret < 0) goto out; msecs = secs * MSEC_PER_SEC; if (msecs > UINT_MAX) msecs = UINT_MAX; stop_scan_thread(); if (msecs) { WRITE_ONCE(jiffies_scan_wait, msecs_to_jiffies(msecs)); start_scan_thread(); } } else if (strncmp(buf, "scan", 4) == 0) kmemleak_scan(); else if (strncmp(buf, "dump=", 5) == 0) ret = dump_str_object_info(buf + 5); else ret = -EINVAL; out: mutex_unlock(&scan_mutex); if (ret < 0) return ret; /* ignore the rest of the buffer, only one command at a time */ *ppos += size; return size; } static const struct file_operations kmemleak_fops = { .owner = THIS_MODULE, .open = kmemleak_open, .read = seq_read, .write = kmemleak_write, .llseek = seq_lseek, .release = seq_release, }; static void __kmemleak_do_cleanup(void) { struct kmemleak_object *object, *tmp; /* * Kmemleak has already been disabled, no need for RCU list traversal * or kmemleak_lock held. */ list_for_each_entry_safe(object, tmp, &object_list, object_list) { __remove_object(object); __delete_object(object); } } /* * Stop the memory scanning thread and free the kmemleak internal objects if * no previous scan thread (otherwise, kmemleak may still have some useful * information on memory leaks). */ static void kmemleak_do_cleanup(struct work_struct *work) { stop_scan_thread(); mutex_lock(&scan_mutex); /* * Once it is made sure that kmemleak_scan has stopped, it is safe to no * longer track object freeing. Ordering of the scan thread stopping and * the memory accesses below is guaranteed by the kthread_stop() * function. */ kmemleak_free_enabled = 0; mutex_unlock(&scan_mutex); if (!kmemleak_found_leaks) __kmemleak_do_cleanup(); else pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n"); } static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup); /* * Disable kmemleak. No memory allocation/freeing will be traced once this * function is called. Disabling kmemleak is an irreversible operation. */ static void kmemleak_disable(void) { /* atomically check whether it was already invoked */ if (cmpxchg(&kmemleak_error, 0, 1)) return; /* stop any memory operation tracing */ kmemleak_enabled = 0; /* check whether it is too early for a kernel thread */ if (kmemleak_late_initialized) schedule_work(&cleanup_work); else kmemleak_free_enabled = 0; pr_info("Kernel memory leak detector disabled\n"); } /* * Allow boot-time kmemleak disabling (enabled by default). */ static int __init kmemleak_boot_config(char *str) { if (!str) return -EINVAL; if (strcmp(str, "off") == 0) kmemleak_disable(); else if (strcmp(str, "on") == 0) { kmemleak_skip_disable = 1; stack_depot_request_early_init(); } else return -EINVAL; return 0; } early_param("kmemleak", kmemleak_boot_config); /* * Kmemleak initialization. */ void __init kmemleak_init(void) { #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF if (!kmemleak_skip_disable) { kmemleak_disable(); return; } #endif if (kmemleak_error) return; jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE); jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000); object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE); scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE); /* register the data/bss sections */ create_object((unsigned long)_sdata, _edata - _sdata, KMEMLEAK_GREY, GFP_ATOMIC); create_object((unsigned long)__bss_start, __bss_stop - __bss_start, KMEMLEAK_GREY, GFP_ATOMIC); /* only register .data..ro_after_init if not within .data */ if (&__start_ro_after_init < &_sdata || &__end_ro_after_init > &_edata) create_object((unsigned long)__start_ro_after_init, __end_ro_after_init - __start_ro_after_init, KMEMLEAK_GREY, GFP_ATOMIC); } /* * Late initialization function. */ static int __init kmemleak_late_init(void) { kmemleak_late_initialized = 1; debugfs_create_file("kmemleak", 0644, NULL, NULL, &kmemleak_fops); if (kmemleak_error) { /* * Some error occurred and kmemleak was disabled. There is a * small chance that kmemleak_disable() was called immediately * after setting kmemleak_late_initialized and we may end up with * two clean-up threads but serialized by scan_mutex. */ schedule_work(&cleanup_work); return -ENOMEM; } if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN)) { mutex_lock(&scan_mutex); start_scan_thread(); mutex_unlock(&scan_mutex); } pr_info("Kernel memory leak detector initialized (mem pool available: %d)\n", mem_pool_free_count); return 0; } late_initcall(kmemleak_late_init);
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