diff --git a/fs/file_table.c b/fs/file_table.c index 3cac9c34264f..eed5ffad9997 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -521,9 +521,14 @@ EXPORT_SYMBOL(__fput_sync); void __init files_init(void) { - filp_cachep = kmem_cache_create_rcu("filp", sizeof(struct file), - offsetof(struct file, f_freeptr), - SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT); + struct kmem_cache_args args = { + .use_freeptr_offset = true, + .freeptr_offset = offsetof(struct file, f_freeptr), + }; + + filp_cachep = kmem_cache_create("filp", sizeof(struct file), &args, + SLAB_HWCACHE_ALIGN | SLAB_PANIC | + SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU); percpu_counter_init(&nr_files, 0, GFP_KERNEL); } diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 70d6a8f6e25d..00a3bf7c0d8f 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -175,13 +175,59 @@ static __always_inline void * __must_check kasan_init_slab_obj( return (void *)object; } -bool __kasan_slab_free(struct kmem_cache *s, void *object, - unsigned long ip, bool init); -static __always_inline bool kasan_slab_free(struct kmem_cache *s, - void *object, bool init) +bool __kasan_slab_pre_free(struct kmem_cache *s, void *object, + unsigned long ip); +/** + * kasan_slab_pre_free - Check whether freeing a slab object is safe. + * @object: Object to be freed. + * + * This function checks whether freeing the given object is safe. It may + * check for double-free and invalid-free bugs and report them. + * + * This function is intended only for use by the slab allocator. + * + * @Return true if freeing the object is unsafe; false otherwise. + */ +static __always_inline bool kasan_slab_pre_free(struct kmem_cache *s, + void *object) { if (kasan_enabled()) - return __kasan_slab_free(s, object, _RET_IP_, init); + return __kasan_slab_pre_free(s, object, _RET_IP_); + return false; +} + +bool __kasan_slab_free(struct kmem_cache *s, void *object, bool init, + bool still_accessible); +/** + * kasan_slab_free - Poison, initialize, and quarantine a slab object. + * @object: Object to be freed. + * @init: Whether to initialize the object. + * @still_accessible: Whether the object contents are still accessible. + * + * This function informs that a slab object has been freed and is not + * supposed to be accessed anymore, except when @still_accessible is set + * (indicating that the object is in a SLAB_TYPESAFE_BY_RCU cache and an RCU + * grace period might not have passed yet). + * + * For KASAN modes that have integrated memory initialization + * (kasan_has_integrated_init() == true), this function also initializes + * the object's memory. For other modes, the @init argument is ignored. + * + * This function might also take ownership of the object to quarantine it. + * When this happens, KASAN will defer freeing the object to a later + * stage and handle it internally until then. The return value indicates + * whether KASAN took ownership of the object. + * + * This function is intended only for use by the slab allocator. + * + * @Return true if KASAN took ownership of the object; false otherwise. + */ +static __always_inline bool kasan_slab_free(struct kmem_cache *s, + void *object, bool init, + bool still_accessible) +{ + if (kasan_enabled()) + return __kasan_slab_free(s, object, init, still_accessible); return false; } @@ -371,7 +417,14 @@ static inline void *kasan_init_slab_obj(struct kmem_cache *cache, { return (void *)object; } -static inline bool kasan_slab_free(struct kmem_cache *s, void *object, bool init) + +static inline bool kasan_slab_pre_free(struct kmem_cache *s, void *object) +{ + return false; +} + +static inline bool kasan_slab_free(struct kmem_cache *s, void *object, + bool init, bool still_accessible) { return false; } diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index cf2b5a188f78..0ee270b3f5ed 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -111,6 +111,11 @@ static inline void __kvfree_call_rcu(struct rcu_head *head, void *ptr) kvfree(ptr); } +static inline void kvfree_rcu_barrier(void) +{ + rcu_barrier(); +} + #ifdef CONFIG_KASAN_GENERIC void kvfree_call_rcu(struct rcu_head *head, void *ptr); #else diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h index 7dbde2b6f714..90a684f94776 100644 --- a/include/linux/rcutree.h +++ b/include/linux/rcutree.h @@ -35,6 +35,7 @@ static inline void rcu_virt_note_context_switch(void) void synchronize_rcu_expedited(void); void kvfree_call_rcu(struct rcu_head *head, void *ptr); +void kvfree_rcu_barrier(void); void rcu_barrier(void); void rcu_momentary_eqs(void); diff --git a/include/linux/slab.h b/include/linux/slab.h index 5b2da2cf31a8..da3a546571e7 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -240,17 +240,173 @@ struct mem_cgroup; */ bool slab_is_available(void); -struct kmem_cache *kmem_cache_create(const char *name, unsigned int size, - unsigned int align, slab_flags_t flags, - void (*ctor)(void *)); -struct kmem_cache *kmem_cache_create_usercopy(const char *name, - unsigned int size, unsigned int align, - slab_flags_t flags, - unsigned int useroffset, unsigned int usersize, - void (*ctor)(void *)); -struct kmem_cache *kmem_cache_create_rcu(const char *name, unsigned int size, - unsigned int freeptr_offset, - slab_flags_t flags); +/** + * struct kmem_cache_args - Less common arguments for kmem_cache_create() + * + * Any uninitialized fields of the structure are interpreted as unused. The + * exception is @freeptr_offset where %0 is a valid value, so + * @use_freeptr_offset must be also set to %true in order to interpret the field + * as used. For @useroffset %0 is also valid, but only with non-%0 + * @usersize. + * + * When %NULL args is passed to kmem_cache_create(), it is equivalent to all + * fields unused. + */ +struct kmem_cache_args { + /** + * @align: The required alignment for the objects. + * + * %0 means no specific alignment is requested. + */ + unsigned int align; + /** + * @useroffset: Usercopy region offset. + * + * %0 is a valid offset, when @usersize is non-%0 + */ + unsigned int useroffset; + /** + * @usersize: Usercopy region size. + * + * %0 means no usercopy region is specified. + */ + unsigned int usersize; + /** + * @freeptr_offset: Custom offset for the free pointer + * in &SLAB_TYPESAFE_BY_RCU caches + * + * By default &SLAB_TYPESAFE_BY_RCU caches place the free pointer + * outside of the object. This might cause the object to grow in size. + * Cache creators that have a reason to avoid this can specify a custom + * free pointer offset in their struct where the free pointer will be + * placed. + * + * Note that placing the free pointer inside the object requires the + * caller to ensure that no fields are invalidated that are required to + * guard against object recycling (See &SLAB_TYPESAFE_BY_RCU for + * details). + * + * Using %0 as a value for @freeptr_offset is valid. If @freeptr_offset + * is specified, %use_freeptr_offset must be set %true. + * + * Note that @ctor currently isn't supported with custom free pointers + * as a @ctor requires an external free pointer. + */ + unsigned int freeptr_offset; + /** + * @use_freeptr_offset: Whether a @freeptr_offset is used. + */ + bool use_freeptr_offset; + /** + * @ctor: A constructor for the objects. + * + * The constructor is invoked for each object in a newly allocated slab + * page. It is the cache user's responsibility to free object in the + * same state as after calling the constructor, or deal appropriately + * with any differences between a freshly constructed and a reallocated + * object. + * + * %NULL means no constructor. + */ + void (*ctor)(void *); +}; + +struct kmem_cache *__kmem_cache_create_args(const char *name, + unsigned int object_size, + struct kmem_cache_args *args, + slab_flags_t flags); +static inline struct kmem_cache * +__kmem_cache_create(const char *name, unsigned int size, unsigned int align, + slab_flags_t flags, void (*ctor)(void *)) +{ + struct kmem_cache_args kmem_args = { + .align = align, + .ctor = ctor, + }; + + return __kmem_cache_create_args(name, size, &kmem_args, flags); +} + +/** + * kmem_cache_create_usercopy - Create a kmem cache with a region suitable + * for copying to userspace. + * @name: A string which is used in /proc/slabinfo to identify this cache. + * @size: The size of objects to be created in this cache. + * @align: The required alignment for the objects. + * @flags: SLAB flags + * @useroffset: Usercopy region offset + * @usersize: Usercopy region size + * @ctor: A constructor for the objects, or %NULL. + * + * This is a legacy wrapper, new code should use either KMEM_CACHE_USERCOPY() + * if whitelisting a single field is sufficient, or kmem_cache_create() with + * the necessary parameters passed via the args parameter (see + * &struct kmem_cache_args) + * + * Return: a pointer to the cache on success, NULL on failure. + */ +static inline struct kmem_cache * +kmem_cache_create_usercopy(const char *name, unsigned int size, + unsigned int align, slab_flags_t flags, + unsigned int useroffset, unsigned int usersize, + void (*ctor)(void *)) +{ + struct kmem_cache_args kmem_args = { + .align = align, + .ctor = ctor, + .useroffset = useroffset, + .usersize = usersize, + }; + + return __kmem_cache_create_args(name, size, &kmem_args, flags); +} + +/* If NULL is passed for @args, use this variant with default arguments. */ +static inline struct kmem_cache * +__kmem_cache_default_args(const char *name, unsigned int size, + struct kmem_cache_args *args, + slab_flags_t flags) +{ + struct kmem_cache_args kmem_default_args = {}; + + /* Make sure we don't get passed garbage. */ + if (WARN_ON_ONCE(args)) + return ERR_PTR(-EINVAL); + + return __kmem_cache_create_args(name, size, &kmem_default_args, flags); +} + +/** + * kmem_cache_create - Create a kmem cache. + * @__name: A string which is used in /proc/slabinfo to identify this cache. + * @__object_size: The size of objects to be created in this cache. + * @__args: Optional arguments, see &struct kmem_cache_args. Passing %NULL + * means defaults will be used for all the arguments. + * + * This is currently implemented as a macro using ``_Generic()`` to call + * either the new variant of the function, or a legacy one. + * + * The new variant has 4 parameters: + * ``kmem_cache_create(name, object_size, args, flags)`` + * + * See __kmem_cache_create_args() which implements this. + * + * The legacy variant has 5 parameters: + * ``kmem_cache_create(name, object_size, align, flags, ctor)`` + * + * The align and ctor parameters map to the respective fields of + * &struct kmem_cache_args + * + * Context: Cannot be called within a interrupt, but can be interrupted. + * + * Return: a pointer to the cache on success, NULL on failure. + */ +#define kmem_cache_create(__name, __object_size, __args, ...) \ + _Generic((__args), \ + struct kmem_cache_args *: __kmem_cache_create_args, \ + void *: __kmem_cache_default_args, \ + default: __kmem_cache_create)(__name, __object_size, __args, __VA_ARGS__) + void kmem_cache_destroy(struct kmem_cache *s); int kmem_cache_shrink(struct kmem_cache *s); @@ -262,20 +418,23 @@ int kmem_cache_shrink(struct kmem_cache *s); * f.e. add ____cacheline_aligned_in_smp to the struct declaration * then the objects will be properly aligned in SMP configurations. */ -#define KMEM_CACHE(__struct, __flags) \ - kmem_cache_create(#__struct, sizeof(struct __struct), \ - __alignof__(struct __struct), (__flags), NULL) +#define KMEM_CACHE(__struct, __flags) \ + __kmem_cache_create_args(#__struct, sizeof(struct __struct), \ + &(struct kmem_cache_args) { \ + .align = __alignof__(struct __struct), \ + }, (__flags)) /* * To whitelist a single field for copying to/from usercopy, use this * macro instead for KMEM_CACHE() above. */ -#define KMEM_CACHE_USERCOPY(__struct, __flags, __field) \ - kmem_cache_create_usercopy(#__struct, \ - sizeof(struct __struct), \ - __alignof__(struct __struct), (__flags), \ - offsetof(struct __struct, __field), \ - sizeof_field(struct __struct, __field), NULL) +#define KMEM_CACHE_USERCOPY(__struct, __flags, __field) \ + __kmem_cache_create_args(#__struct, sizeof(struct __struct), \ + &(struct kmem_cache_args) { \ + .align = __alignof__(struct __struct), \ + .useroffset = offsetof(struct __struct, __field), \ + .usersize = sizeof_field(struct __struct, __field), \ + }, (__flags)) /* * Common kmalloc functions provided by all allocators @@ -556,6 +715,35 @@ void *kmem_cache_alloc_lru_noprof(struct kmem_cache *s, struct list_lru *lru, gfp_t gfpflags) __assume_slab_alignment __malloc; #define kmem_cache_alloc_lru(...) alloc_hooks(kmem_cache_alloc_lru_noprof(__VA_ARGS__)) +/** + * kmem_cache_charge - memcg charge an already allocated slab memory + * @objp: address of the slab object to memcg charge + * @gfpflags: describe the allocation context + * + * kmem_cache_charge allows charging a slab object to the current memcg, + * primarily in cases where charging at allocation time might not be possible + * because the target memcg is not known (i.e. softirq context) + * + * The objp should be pointer returned by the slab allocator functions like + * kmalloc (with __GFP_ACCOUNT in flags) or kmem_cache_alloc. The memcg charge + * behavior can be controlled through gfpflags parameter, which affects how the + * necessary internal metadata can be allocated. Including __GFP_NOFAIL denotes + * that overcharging is requested instead of failure, but is not applied for the + * internal metadata allocation. + * + * There are several cases where it will return true even if the charging was + * not done: + * More specifically: + * + * 1. For !CONFIG_MEMCG or cgroup_disable=memory systems. + * 2. Already charged slab objects. + * 3. For slab objects from KMALLOC_NORMAL caches - allocated by kmalloc() + * without __GFP_ACCOUNT + * 4. Allocating internal metadata has failed + * + * Return: true if charge was successful otherwise false. + */ +bool kmem_cache_charge(void *objp, gfp_t gfpflags); void kmem_cache_free(struct kmem_cache *s, void *objp); kmem_buckets *kmem_buckets_create(const char *name, slab_flags_t flags, diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 86cf31902841..f3570e81ecb4 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3755,6 +3755,11 @@ SYSCALL_DEFINE2(io_uring_setup, u32, entries, static int __init io_uring_init(void) { + struct kmem_cache_args kmem_args = { + .useroffset = offsetof(struct io_kiocb, cmd.data), + .usersize = sizeof_field(struct io_kiocb, cmd.data), + }; + #define __BUILD_BUG_VERIFY_OFFSET_SIZE(stype, eoffset, esize, ename) do { \ BUILD_BUG_ON(offsetof(stype, ename) != eoffset); \ BUILD_BUG_ON(sizeof_field(stype, ename) != esize); \ @@ -3839,12 +3844,9 @@ static int __init io_uring_init(void) * range, and HARDENED_USERCOPY will complain if we haven't * correctly annotated this range. */ - req_cachep = kmem_cache_create_usercopy("io_kiocb", - sizeof(struct io_kiocb), 0, - SLAB_HWCACHE_ALIGN | SLAB_PANIC | - SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU, - offsetof(struct io_kiocb, cmd.data), - sizeof_field(struct io_kiocb, cmd.data), NULL); + req_cachep = kmem_cache_create("io_kiocb", sizeof(struct io_kiocb), &kmem_args, + SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT | + SLAB_TYPESAFE_BY_RCU); io_buf_cachep = KMEM_CACHE(io_buffer, SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e056230551f7..a60616e69b66 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3564,18 +3564,15 @@ kvfree_rcu_drain_ready(struct kfree_rcu_cpu *krcp) } /* - * This function is invoked after the KFREE_DRAIN_JIFFIES timeout. + * Return: %true if a work is queued, %false otherwise. */ -static void kfree_rcu_monitor(struct work_struct *work) +static bool +kvfree_rcu_queue_batch(struct kfree_rcu_cpu *krcp) { - struct kfree_rcu_cpu *krcp = container_of(work, - struct kfree_rcu_cpu, monitor_work.work); unsigned long flags; + bool queued = false; int i, j; - // Drain ready for reclaim. - kvfree_rcu_drain_ready(krcp); - raw_spin_lock_irqsave(&krcp->lock, flags); // Attempt to start a new batch. @@ -3614,11 +3611,27 @@ static void kfree_rcu_monitor(struct work_struct *work) // be that the work is in the pending state when // channels have been detached following by each // other. - queue_rcu_work(system_unbound_wq, &krwp->rcu_work); + queued = queue_rcu_work(system_unbound_wq, &krwp->rcu_work); } } raw_spin_unlock_irqrestore(&krcp->lock, flags); + return queued; +} + +/* + * This function is invoked after the KFREE_DRAIN_JIFFIES timeout. + */ +static void kfree_rcu_monitor(struct work_struct *work) +{ + struct kfree_rcu_cpu *krcp = container_of(work, + struct kfree_rcu_cpu, monitor_work.work); + + // Drain ready for reclaim. + kvfree_rcu_drain_ready(krcp); + + // Queue a batch for a rest. + kvfree_rcu_queue_batch(krcp); // If there is nothing to detach, it means that our job is // successfully done here. In case of having at least one @@ -3840,6 +3853,86 @@ unlock_return: } EXPORT_SYMBOL_GPL(kvfree_call_rcu); +/** + * kvfree_rcu_barrier - Wait until all in-flight kvfree_rcu() complete. + * + * Note that a single argument of kvfree_rcu() call has a slow path that + * triggers synchronize_rcu() following by freeing a pointer. It is done + * before the return from the function. Therefore for any single-argument + * call that will result in a kfree() to a cache that is to be destroyed + * during module exit, it is developer's responsibility to ensure that all + * such calls have returned before the call to kmem_cache_destroy(). + */ +void kvfree_rcu_barrier(void) +{ + struct kfree_rcu_cpu_work *krwp; + struct kfree_rcu_cpu *krcp; + bool queued; + int i, cpu; + + /* + * Firstly we detach objects and queue them over an RCU-batch + * for all CPUs. Finally queued works are flushed for each CPU. + * + * Please note. If there are outstanding batches for a particular + * CPU, those have to be finished first following by queuing a new. + */ + for_each_possible_cpu(cpu) { + krcp = per_cpu_ptr(&krc, cpu); + + /* + * Check if this CPU has any objects which have been queued for a + * new GP completion. If not(means nothing to detach), we are done + * with it. If any batch is pending/running for this "krcp", below + * per-cpu flush_rcu_work() waits its completion(see last step). + */ + if (!need_offload_krc(krcp)) + continue; + + while (1) { + /* + * If we are not able to queue a new RCU work it means: + * - batches for this CPU are still in flight which should + * be flushed first and then repeat; + * - no objects to detach, because of concurrency. + */ + queued = kvfree_rcu_queue_batch(krcp); + + /* + * Bail out, if there is no need to offload this "krcp" + * anymore. As noted earlier it can run concurrently. + */ + if (queued || !need_offload_krc(krcp)) + break; + + /* There are ongoing batches. */ + for (i = 0; i < KFREE_N_BATCHES; i++) { + krwp = &(krcp->krw_arr[i]); + flush_rcu_work(&krwp->rcu_work); + } + } + } + + /* + * Now we guarantee that all objects are flushed. + */ + for_each_possible_cpu(cpu) { + krcp = per_cpu_ptr(&krc, cpu); + + /* + * A monitor work can drain ready to reclaim objects + * directly. Wait its completion if running or pending. + */ + cancel_delayed_work_sync(&krcp->monitor_work); + + for (i = 0; i < KFREE_N_BATCHES; i++) { + krwp = &(krcp->krw_arr[i]); + flush_rcu_work(&krwp->rcu_work); + } + } +} +EXPORT_SYMBOL_GPL(kvfree_rcu_barrier); + static unsigned long kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) { diff --git a/lib/slub_kunit.c b/lib/slub_kunit.c index e6667a28c014..6e3a1e5a7142 100644 --- a/lib/slub_kunit.c +++ b/lib/slub_kunit.c @@ -5,6 +5,7 @@ #include #include #include +#include #include "../mm/slab.h" static struct kunit_resource resource; @@ -157,6 +158,34 @@ static void test_kmalloc_redzone_access(struct kunit *test) kmem_cache_destroy(s); } +struct test_kfree_rcu_struct { + struct rcu_head rcu; +}; + +static void test_kfree_rcu(struct kunit *test) +{ + struct kmem_cache *s = test_kmem_cache_create("TestSlub_kfree_rcu", + sizeof(struct test_kfree_rcu_struct), + SLAB_NO_MERGE); + struct test_kfree_rcu_struct *p = kmem_cache_alloc(s, GFP_KERNEL); + + kfree_rcu(p, rcu); + kmem_cache_destroy(s); + + KUNIT_EXPECT_EQ(test, 0, slab_errors); +} + +static void test_leak_destroy(struct kunit *test) +{ + struct kmem_cache *s = test_kmem_cache_create("TestSlub_kfree_rcu", + 64, SLAB_NO_MERGE); + kmem_cache_alloc(s, GFP_KERNEL); + + kmem_cache_destroy(s); + + KUNIT_EXPECT_EQ(test, 1, slab_errors); +} + static int test_init(struct kunit *test) { slab_errors = 0; @@ -177,6 +206,8 @@ static struct kunit_case test_cases[] = { KUNIT_CASE(test_clobber_redzone_free), KUNIT_CASE(test_kmalloc_redzone_access), + KUNIT_CASE(test_kfree_rcu), + KUNIT_CASE(test_leak_destroy), {} }; diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index afc72fde0f03..41a58536531d 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -70,6 +70,38 @@ config SLUB_DEBUG_ON off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying "slab_debug=-". +config SLUB_RCU_DEBUG + bool "Enable UAF detection in TYPESAFE_BY_RCU caches (for KASAN)" + depends on SLUB_DEBUG + # SLUB_RCU_DEBUG should build fine without KASAN, but is currently useless + # without KASAN, so mark it as a dependency of KASAN for now. + depends on KASAN + default KASAN_GENERIC || KASAN_SW_TAGS + help + Make SLAB_TYPESAFE_BY_RCU caches behave approximately as if the cache + was not marked as SLAB_TYPESAFE_BY_RCU and every caller used + kfree_rcu() instead. + + This is intended for use in combination with KASAN, to enable KASAN to + detect use-after-free accesses in such caches. + (KFENCE is able to do that independent of this flag.) + + This might degrade performance. + Unfortunately this also prevents a very specific bug pattern from + triggering (insufficient checks against an object being recycled + within the RCU grace period); so this option can be turned off even on + KASAN builds, in case you want to test for such a bug. + + If you're using this for testing bugs / fuzzing and care about + catching all the bugs WAY more than performance, you might want to + also turn on CONFIG_RCU_STRICT_GRACE_PERIOD. + + WARNING: + This is designed as a debugging feature, not a security feature. + Objects are sometimes recycled without RCU delay under memory pressure. + + If unsure, say N. + config PAGE_OWNER bool "Track page owner" depends on DEBUG_KERNEL && STACKTRACE_SUPPORT diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 85e7c6b4575c..ed4873e18c75 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -208,15 +208,12 @@ void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache, return (void *)object; } -static inline bool poison_slab_object(struct kmem_cache *cache, void *object, - unsigned long ip, bool init) +/* Returns true when freeing the object is not safe. */ +static bool check_slab_allocation(struct kmem_cache *cache, void *object, + unsigned long ip) { - void *tagged_object; + void *tagged_object = object; - if (!kasan_arch_is_ready()) - return false; - - tagged_object = object; object = kasan_reset_tag(object); if (unlikely(nearest_obj(cache, virt_to_slab(object), object) != object)) { @@ -224,37 +221,47 @@ static inline bool poison_slab_object(struct kmem_cache *cache, void *object, return true; } - /* RCU slabs could be legally used after free within the RCU period. */ - if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU)) - return false; - if (!kasan_byte_accessible(tagged_object)) { kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_DOUBLE_FREE); return true; } + return false; +} + +static inline void poison_slab_object(struct kmem_cache *cache, void *object, + bool init, bool still_accessible) +{ + void *tagged_object = object; + + object = kasan_reset_tag(object); + + /* RCU slabs could be legally used after free within the RCU period. */ + if (unlikely(still_accessible)) + return; + kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE), KASAN_SLAB_FREE, init); if (kasan_stack_collection_enabled()) kasan_save_free_info(cache, tagged_object); - - return false; } -bool __kasan_slab_free(struct kmem_cache *cache, void *object, - unsigned long ip, bool init) +bool __kasan_slab_pre_free(struct kmem_cache *cache, void *object, + unsigned long ip) { - if (is_kfence_address(object)) + if (!kasan_arch_is_ready() || is_kfence_address(object)) + return false; + return check_slab_allocation(cache, object, ip); +} + +bool __kasan_slab_free(struct kmem_cache *cache, void *object, bool init, + bool still_accessible) +{ + if (!kasan_arch_is_ready() || is_kfence_address(object)) return false; - /* - * If the object is buggy, do not let slab put the object onto the - * freelist. The object will thus never be allocated again and its - * metadata will never get released. - */ - if (poison_slab_object(cache, object, ip, init)) - return true; + poison_slab_object(cache, object, init, still_accessible); /* * If the object is put into quarantine, do not let slab put the object @@ -504,11 +511,16 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip) return true; } - if (is_kfence_address(ptr)) - return false; + if (is_kfence_address(ptr) || !kasan_arch_is_ready()) + return true; slab = folio_slab(folio); - return !poison_slab_object(slab->slab_cache, ptr, ip, false); + + if (check_slab_allocation(slab->slab_cache, ptr, ip)) + return false; + + poison_slab_object(slab->slab_cache, ptr, false, false); + return true; } void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip) diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c index 7b32be2a3cf0..567d33b493e2 100644 --- a/mm/kasan/kasan_test.c +++ b/mm/kasan/kasan_test.c @@ -996,6 +996,51 @@ static void kmem_cache_invalid_free(struct kunit *test) kmem_cache_destroy(cache); } +static void kmem_cache_rcu_uaf(struct kunit *test) +{ + char *p; + size_t size = 200; + struct kmem_cache *cache; + + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB_RCU_DEBUG); + + cache = kmem_cache_create("test_cache", size, 0, SLAB_TYPESAFE_BY_RCU, + NULL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache); + + p = kmem_cache_alloc(cache, GFP_KERNEL); + if (!p) { + kunit_err(test, "Allocation failed: %s\n", __func__); + kmem_cache_destroy(cache); + return; + } + *p = 1; + + rcu_read_lock(); + + /* Free the object - this will internally schedule an RCU callback. */ + kmem_cache_free(cache, p); + + /* + * We should still be allowed to access the object at this point because + * the cache is SLAB_TYPESAFE_BY_RCU and we've been in an RCU read-side + * critical section since before the kmem_cache_free(). + */ + READ_ONCE(*p); + + rcu_read_unlock(); + + /* + * Wait for the RCU callback to execute; after this, the object should + * have actually been freed from KASAN's perspective. + */ + rcu_barrier(); + + KUNIT_EXPECT_KASAN_FAIL(test, READ_ONCE(*p)); + + kmem_cache_destroy(cache); +} + static void empty_cache_ctor(void *object) { } static void kmem_cache_double_destroy(struct kunit *test) @@ -1937,6 +1982,7 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(kmem_cache_oob), KUNIT_CASE(kmem_cache_double_free), KUNIT_CASE(kmem_cache_invalid_free), + KUNIT_CASE(kmem_cache_rcu_uaf), KUNIT_CASE(kmem_cache_double_destroy), KUNIT_CASE(kmem_cache_accounted), KUNIT_CASE(kmem_cache_bulk), diff --git a/mm/slab.h b/mm/slab.h index a6051385186e..f22fb760b286 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -261,8 +261,6 @@ struct kmem_cache { unsigned int object_size; /* Object size without metadata */ struct reciprocal_value reciprocal_size; unsigned int offset; /* Free pointer offset */ - /* Specific free pointer requested (if not UINT_MAX) */ - unsigned int rcu_freeptr_offset; #ifdef CONFIG_SLUB_CPU_PARTIAL /* Number of per cpu partial objects to keep around */ unsigned int cpu_partial; @@ -424,7 +422,9 @@ kmalloc_slab(size_t size, kmem_buckets *b, gfp_t flags, unsigned long caller) gfp_t kmalloc_fix_flags(gfp_t flags); /* Functions provided by the slab allocators */ -int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags); +int do_kmem_cache_create(struct kmem_cache *s, const char *name, + unsigned int size, struct kmem_cache_args *args, + slab_flags_t flags); void __init kmem_cache_init(void); extern void create_boot_cache(struct kmem_cache *, const char *name, @@ -445,6 +445,13 @@ static inline bool is_kmalloc_cache(struct kmem_cache *s) return (s->flags & SLAB_KMALLOC); } +static inline bool is_kmalloc_normal(struct kmem_cache *s) +{ + if (!is_kmalloc_cache(s)) + return false; + return !(s->flags & (SLAB_CACHE_DMA|SLAB_ACCOUNT|SLAB_RECLAIM_ACCOUNT)); +} + /* Legal flag mask for kmem_cache_create(), for various configurations */ #define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | \ SLAB_CACHE_DMA32 | SLAB_PANIC | \ diff --git a/mm/slab_common.c b/mm/slab_common.c index 95db3702f8d6..61f32420230a 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -40,11 +40,6 @@ LIST_HEAD(slab_caches); DEFINE_MUTEX(slab_mutex); struct kmem_cache *kmem_cache; -static LIST_HEAD(slab_caches_to_rcu_destroy); -static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); -static DECLARE_WORK(slab_caches_to_rcu_destroy_work, - slab_caches_to_rcu_destroy_workfn); - /* * Set of flags that will prevent slab merging */ @@ -88,6 +83,19 @@ unsigned int kmem_cache_size(struct kmem_cache *s) EXPORT_SYMBOL(kmem_cache_size); #ifdef CONFIG_DEBUG_VM + +static bool kmem_cache_is_duplicate_name(const char *name) +{ + struct kmem_cache *s; + + list_for_each_entry(s, &slab_caches, list) { + if (!strcmp(s->name, name)) + return true; + } + + return false; +} + static int kmem_cache_sanity_check(const char *name, unsigned int size) { if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { @@ -95,6 +103,10 @@ static int kmem_cache_sanity_check(const char *name, unsigned int size) return -EINVAL; } + /* Duplicate names will confuse slabtop, et al */ + WARN(kmem_cache_is_duplicate_name(name), + "kmem_cache of name '%s' already exists\n", name); + WARN_ON(strchr(name, ' ')); /* It confuses parsers */ return 0; } @@ -169,14 +181,15 @@ struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, if (ctor) return NULL; - size = ALIGN(size, sizeof(void *)); - align = calculate_alignment(flags, align, size); - size = ALIGN(size, align); flags = kmem_cache_flags(flags, name); if (flags & SLAB_NEVER_MERGE) return NULL; + size = ALIGN(size, sizeof(void *)); + align = calculate_alignment(flags, align, size); + size = ALIGN(size, align); + list_for_each_entry_reverse(s, &slab_caches, list) { if (slab_unmergeable(s)) continue; @@ -202,39 +215,29 @@ struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, } static struct kmem_cache *create_cache(const char *name, - unsigned int object_size, unsigned int freeptr_offset, - unsigned int align, slab_flags_t flags, - unsigned int useroffset, unsigned int usersize, - void (*ctor)(void *)) + unsigned int object_size, + struct kmem_cache_args *args, + slab_flags_t flags) { struct kmem_cache *s; int err; - if (WARN_ON(useroffset + usersize > object_size)) - useroffset = usersize = 0; + if (WARN_ON(args->useroffset + args->usersize > object_size)) + args->useroffset = args->usersize = 0; /* If a custom freelist pointer is requested make sure it's sane. */ err = -EINVAL; - if (freeptr_offset != UINT_MAX && - (freeptr_offset >= object_size || !(flags & SLAB_TYPESAFE_BY_RCU) || - !IS_ALIGNED(freeptr_offset, sizeof(freeptr_t)))) + if (args->use_freeptr_offset && + (args->freeptr_offset >= object_size || + !(flags & SLAB_TYPESAFE_BY_RCU) || + !IS_ALIGNED(args->freeptr_offset, sizeof(freeptr_t)))) goto out; err = -ENOMEM; s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); if (!s) goto out; - - s->name = name; - s->size = s->object_size = object_size; - s->rcu_freeptr_offset = freeptr_offset; - s->align = align; - s->ctor = ctor; -#ifdef CONFIG_HARDENED_USERCOPY - s->useroffset = useroffset; - s->usersize = usersize; -#endif - err = __kmem_cache_create(s, flags); + err = do_kmem_cache_create(s, name, object_size, args, flags); if (err) goto out_free_cache; @@ -248,12 +251,25 @@ out: return ERR_PTR(err); } -static struct kmem_cache * -do_kmem_cache_create_usercopy(const char *name, - unsigned int size, unsigned int freeptr_offset, - unsigned int align, slab_flags_t flags, - unsigned int useroffset, unsigned int usersize, - void (*ctor)(void *)) +/** + * __kmem_cache_create_args - Create a kmem cache. + * @name: A string which is used in /proc/slabinfo to identify this cache. + * @object_size: The size of objects to be created in this cache. + * @args: Additional arguments for the cache creation (see + * &struct kmem_cache_args). + * @flags: See %SLAB_* flags for an explanation of individual @flags. + * + * Not to be called directly, use the kmem_cache_create() wrapper with the same + * parameters. + * + * Context: Cannot be called within a interrupt, but can be interrupted. + * + * Return: a pointer to the cache on success, NULL on failure. + */ +struct kmem_cache *__kmem_cache_create_args(const char *name, + unsigned int object_size, + struct kmem_cache_args *args, + slab_flags_t flags) { struct kmem_cache *s = NULL; const char *cache_name; @@ -275,7 +291,7 @@ do_kmem_cache_create_usercopy(const char *name, mutex_lock(&slab_mutex); - err = kmem_cache_sanity_check(name, size); + err = kmem_cache_sanity_check(name, object_size); if (err) { goto out_unlock; } @@ -296,12 +312,14 @@ do_kmem_cache_create_usercopy(const char *name, /* Fail closed on bad usersize of useroffset values. */ if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) || - WARN_ON(!usersize && useroffset) || - WARN_ON(size < usersize || size - usersize < useroffset)) - usersize = useroffset = 0; + WARN_ON(!args->usersize && args->useroffset) || + WARN_ON(object_size < args->usersize || + object_size - args->usersize < args->useroffset)) + args->usersize = args->useroffset = 0; - if (!usersize) - s = __kmem_cache_alias(name, size, align, flags, ctor); + if (!args->usersize) + s = __kmem_cache_alias(name, object_size, args->align, flags, + args->ctor); if (s) goto out_unlock; @@ -311,9 +329,8 @@ do_kmem_cache_create_usercopy(const char *name, goto out_unlock; } - s = create_cache(cache_name, size, freeptr_offset, - calculate_alignment(flags, align, size), - flags, useroffset, usersize, ctor); + args->align = calculate_alignment(flags, args->align, object_size); + s = create_cache(cache_name, object_size, args, flags); if (IS_ERR(s)) { err = PTR_ERR(s); kfree_const(cache_name); @@ -335,118 +352,7 @@ out_unlock: } return s; } - -/** - * kmem_cache_create_usercopy - Create a cache with a region suitable - * for copying to userspace - * @name: A string which is used in /proc/slabinfo to identify this cache. - * @size: The size of objects to be created in this cache. - * @align: The required alignment for the objects. - * @flags: SLAB flags - * @useroffset: Usercopy region offset - * @usersize: Usercopy region size - * @ctor: A constructor for the objects. - * - * Cannot be called within a interrupt, but can be interrupted. - * The @ctor is run when new pages are allocated by the cache. - * - * The flags are - * - * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) - * to catch references to uninitialised memory. - * - * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check - * for buffer overruns. - * - * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware - * cacheline. This can be beneficial if you're counting cycles as closely - * as davem. - * - * Return: a pointer to the cache on success, NULL on failure. - */ -struct kmem_cache * -kmem_cache_create_usercopy(const char *name, unsigned int size, - unsigned int align, slab_flags_t flags, - unsigned int useroffset, unsigned int usersize, - void (*ctor)(void *)) -{ - return do_kmem_cache_create_usercopy(name, size, UINT_MAX, align, flags, - useroffset, usersize, ctor); -} -EXPORT_SYMBOL(kmem_cache_create_usercopy); - -/** - * kmem_cache_create - Create a cache. - * @name: A string which is used in /proc/slabinfo to identify this cache. - * @size: The size of objects to be created in this cache. - * @align: The required alignment for the objects. - * @flags: SLAB flags - * @ctor: A constructor for the objects. - * - * Cannot be called within a interrupt, but can be interrupted. - * The @ctor is run when new pages are allocated by the cache. - * - * The flags are - * - * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) - * to catch references to uninitialised memory. - * - * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check - * for buffer overruns. - * - * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware - * cacheline. This can be beneficial if you're counting cycles as closely - * as davem. - * - * Return: a pointer to the cache on success, NULL on failure. - */ -struct kmem_cache * -kmem_cache_create(const char *name, unsigned int size, unsigned int align, - slab_flags_t flags, void (*ctor)(void *)) -{ - return do_kmem_cache_create_usercopy(name, size, UINT_MAX, align, flags, - 0, 0, ctor); -} -EXPORT_SYMBOL(kmem_cache_create); - -/** - * kmem_cache_create_rcu - Create a SLAB_TYPESAFE_BY_RCU cache. - * @name: A string which is used in /proc/slabinfo to identify this cache. - * @size: The size of objects to be created in this cache. - * @freeptr_offset: The offset into the memory to the free pointer - * @flags: SLAB flags - * - * Cannot be called within an interrupt, but can be interrupted. - * - * See kmem_cache_create() for an explanation of possible @flags. - * - * By default SLAB_TYPESAFE_BY_RCU caches place the free pointer outside - * of the object. This might cause the object to grow in size. Callers - * that have a reason to avoid this can specify a custom free pointer - * offset in their struct where the free pointer will be placed. - * - * Note that placing the free pointer inside the object requires the - * caller to ensure that no fields are invalidated that are required to - * guard against object recycling (See SLAB_TYPESAFE_BY_RCU for - * details.). - * - * Using zero as a value for @freeptr_offset is valid. To request no - * offset UINT_MAX must be specified. - * - * Note that @ctor isn't supported with custom free pointers as a @ctor - * requires an external free pointer. - * - * Return: a pointer to the cache on success, NULL on failure. - */ -struct kmem_cache *kmem_cache_create_rcu(const char *name, unsigned int size, - unsigned int freeptr_offset, - slab_flags_t flags) -{ - return do_kmem_cache_create_usercopy(name, size, freeptr_offset, 0, - flags | SLAB_TYPESAFE_BY_RCU, 0, 0, - NULL); -} -EXPORT_SYMBOL(kmem_cache_create_rcu); +EXPORT_SYMBOL(__kmem_cache_create_args); static struct kmem_cache *kmem_buckets_cache __ro_after_init; @@ -534,87 +440,25 @@ kmem_buckets *kmem_buckets_create(const char *name, slab_flags_t flags, fail: for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) kmem_cache_destroy((*b)[idx]); - kfree(b); + kmem_cache_free(kmem_buckets_cache, b); return NULL; } EXPORT_SYMBOL(kmem_buckets_create); -#ifdef SLAB_SUPPORTS_SYSFS /* * For a given kmem_cache, kmem_cache_destroy() should only be called * once or there will be a use-after-free problem. The actual deletion * and release of the kobject does not need slab_mutex or cpu_hotplug_lock * protection. So they are now done without holding those locks. - * - * Note that there will be a slight delay in the deletion of sysfs files - * if kmem_cache_release() is called indrectly from a work function. */ static void kmem_cache_release(struct kmem_cache *s) { - if (slab_state >= FULL) { - sysfs_slab_unlink(s); + kfence_shutdown_cache(s); + if (__is_defined(SLAB_SUPPORTS_SYSFS) && slab_state >= FULL) sysfs_slab_release(s); - } else { + else slab_kmem_cache_release(s); - } -} -#else -static void kmem_cache_release(struct kmem_cache *s) -{ - slab_kmem_cache_release(s); -} -#endif - -static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) -{ - LIST_HEAD(to_destroy); - struct kmem_cache *s, *s2; - - /* - * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the - * @slab_caches_to_rcu_destroy list. The slab pages are freed - * through RCU and the associated kmem_cache are dereferenced - * while freeing the pages, so the kmem_caches should be freed only - * after the pending RCU operations are finished. As rcu_barrier() - * is a pretty slow operation, we batch all pending destructions - * asynchronously. - */ - mutex_lock(&slab_mutex); - list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); - mutex_unlock(&slab_mutex); - - if (list_empty(&to_destroy)) - return; - - rcu_barrier(); - - list_for_each_entry_safe(s, s2, &to_destroy, list) { - debugfs_slab_release(s); - kfence_shutdown_cache(s); - kmem_cache_release(s); - } -} - -static int shutdown_cache(struct kmem_cache *s) -{ - /* free asan quarantined objects */ - kasan_cache_shutdown(s); - - if (__kmem_cache_shutdown(s) != 0) - return -EBUSY; - - list_del(&s->list); - - if (s->flags & SLAB_TYPESAFE_BY_RCU) { - list_add_tail(&s->list, &slab_caches_to_rcu_destroy); - schedule_work(&slab_caches_to_rcu_destroy_work); - } else { - kfence_shutdown_cache(s); - debugfs_slab_release(s); - } - - return 0; } void slab_kmem_cache_release(struct kmem_cache *s) @@ -626,29 +470,63 @@ void slab_kmem_cache_release(struct kmem_cache *s) void kmem_cache_destroy(struct kmem_cache *s) { - int err = -EBUSY; - bool rcu_set; + int err; if (unlikely(!s) || !kasan_check_byte(s)) return; + /* in-flight kfree_rcu()'s may include objects from our cache */ + kvfree_rcu_barrier(); + + if (IS_ENABLED(CONFIG_SLUB_RCU_DEBUG) && + (s->flags & SLAB_TYPESAFE_BY_RCU)) { + /* + * Under CONFIG_SLUB_RCU_DEBUG, when objects in a + * SLAB_TYPESAFE_BY_RCU slab are freed, SLUB will internally + * defer their freeing with call_rcu(). + * Wait for such call_rcu() invocations here before actually + * destroying the cache. + * + * It doesn't matter that we haven't looked at the slab refcount + * yet - slabs with SLAB_TYPESAFE_BY_RCU can't be merged, so + * the refcount should be 1 here. + */ + rcu_barrier(); + } + cpus_read_lock(); mutex_lock(&slab_mutex); - rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; - s->refcount--; - if (s->refcount) - goto out_unlock; + if (s->refcount) { + mutex_unlock(&slab_mutex); + cpus_read_unlock(); + return; + } - err = shutdown_cache(s); + /* free asan quarantined objects */ + kasan_cache_shutdown(s); + + err = __kmem_cache_shutdown(s); WARN(err, "%s %s: Slab cache still has objects when called from %pS", __func__, s->name, (void *)_RET_IP_); -out_unlock: + + list_del(&s->list); + mutex_unlock(&slab_mutex); cpus_read_unlock(); - if (!err && !rcu_set) - kmem_cache_release(s); + + if (slab_state >= FULL) + sysfs_slab_unlink(s); + debugfs_slab_release(s); + + if (err) + return; + + if (s->flags & SLAB_TYPESAFE_BY_RCU) + rcu_barrier(); + + kmem_cache_release(s); } EXPORT_SYMBOL(kmem_cache_destroy); @@ -760,9 +638,7 @@ void __init create_boot_cache(struct kmem_cache *s, const char *name, { int err; unsigned int align = ARCH_KMALLOC_MINALIGN; - - s->name = name; - s->size = s->object_size = size; + struct kmem_cache_args kmem_args = {}; /* * kmalloc caches guarantee alignment of at least the largest @@ -771,14 +647,14 @@ void __init create_boot_cache(struct kmem_cache *s, const char *name, */ if (flags & SLAB_KMALLOC) align = max(align, 1U << (ffs(size) - 1)); - s->align = calculate_alignment(flags, align, size); + kmem_args.align = calculate_alignment(flags, align, size); #ifdef CONFIG_HARDENED_USERCOPY - s->useroffset = useroffset; - s->usersize = usersize; + kmem_args.useroffset = useroffset; + kmem_args.usersize = usersize; #endif - err = __kmem_cache_create(s, flags); + err = do_kmem_cache_create(s, name, size, &kmem_args, flags); if (err) panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", diff --git a/mm/slub.c b/mm/slub.c index be36f1df809c..21f71cb6cc06 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -750,6 +750,50 @@ static inline bool slab_update_freelist(struct kmem_cache *s, struct slab *slab, return false; } +/* + * kmalloc caches has fixed sizes (mostly power of 2), and kmalloc() API + * family will round up the real request size to these fixed ones, so + * there could be an extra area than what is requested. Save the original + * request size in the meta data area, for better debug and sanity check. + */ +static inline void set_orig_size(struct kmem_cache *s, + void *object, unsigned int orig_size) +{ + void *p = kasan_reset_tag(object); + unsigned int kasan_meta_size; + + if (!slub_debug_orig_size(s)) + return; + + /* + * KASAN can save its free meta data inside of the object at offset 0. + * If this meta data size is larger than 'orig_size', it will overlap + * the data redzone in [orig_size+1, object_size]. Thus, we adjust + * 'orig_size' to be as at least as big as KASAN's meta data. + */ + kasan_meta_size = kasan_metadata_size(s, true); + if (kasan_meta_size > orig_size) + orig_size = kasan_meta_size; + + p += get_info_end(s); + p += sizeof(struct track) * 2; + + *(unsigned int *)p = orig_size; +} + +static inline unsigned int get_orig_size(struct kmem_cache *s, void *object) +{ + void *p = kasan_reset_tag(object); + + if (!slub_debug_orig_size(s)) + return s->object_size; + + p += get_info_end(s); + p += sizeof(struct track) * 2; + + return *(unsigned int *)p; +} + #ifdef CONFIG_SLUB_DEBUG static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; static DEFINE_SPINLOCK(object_map_lock); @@ -979,50 +1023,6 @@ static void print_slab_info(const struct slab *slab) &slab->__page_flags); } -/* - * kmalloc caches has fixed sizes (mostly power of 2), and kmalloc() API - * family will round up the real request size to these fixed ones, so - * there could be an extra area than what is requested. Save the original - * request size in the meta data area, for better debug and sanity check. - */ -static inline void set_orig_size(struct kmem_cache *s, - void *object, unsigned int orig_size) -{ - void *p = kasan_reset_tag(object); - unsigned int kasan_meta_size; - - if (!slub_debug_orig_size(s)) - return; - - /* - * KASAN can save its free meta data inside of the object at offset 0. - * If this meta data size is larger than 'orig_size', it will overlap - * the data redzone in [orig_size+1, object_size]. Thus, we adjust - * 'orig_size' to be as at least as big as KASAN's meta data. - */ - kasan_meta_size = kasan_metadata_size(s, true); - if (kasan_meta_size > orig_size) - orig_size = kasan_meta_size; - - p += get_info_end(s); - p += sizeof(struct track) * 2; - - *(unsigned int *)p = orig_size; -} - -static inline unsigned int get_orig_size(struct kmem_cache *s, void *object) -{ - void *p = kasan_reset_tag(object); - - if (!slub_debug_orig_size(s)) - return s->object_size; - - p += get_info_end(s); - p += sizeof(struct track) * 2; - - return *(unsigned int *)p; -} - void skip_orig_size_check(struct kmem_cache *s, const void *object) { set_orig_size(s, (void *)object, s->object_size); @@ -1888,7 +1888,6 @@ static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects) {} static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects) {} - #ifndef CONFIG_SLUB_TINY static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab, void **freelist, void *nextfree) @@ -2183,6 +2182,45 @@ void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p, __memcg_slab_free_hook(s, slab, p, objects, obj_exts); } + +static __fastpath_inline +bool memcg_slab_post_charge(void *p, gfp_t flags) +{ + struct slabobj_ext *slab_exts; + struct kmem_cache *s; + struct folio *folio; + struct slab *slab; + unsigned long off; + + folio = virt_to_folio(p); + if (!folio_test_slab(folio)) { + return folio_memcg_kmem(folio) || + (__memcg_kmem_charge_page(folio_page(folio, 0), flags, + folio_order(folio)) == 0); + } + + slab = folio_slab(folio); + s = slab->slab_cache; + + /* + * Ignore KMALLOC_NORMAL cache to avoid possible circular dependency + * of slab_obj_exts being allocated from the same slab and thus the slab + * becoming effectively unfreeable. + */ + if (is_kmalloc_normal(s)) + return true; + + /* Ignore already charged objects. */ + slab_exts = slab_obj_exts(slab); + if (slab_exts) { + off = obj_to_index(s, slab, p); + if (unlikely(slab_exts[off].objcg)) + return true; + } + + return __memcg_slab_post_alloc_hook(s, NULL, flags, 1, &p); +} + #else /* CONFIG_MEMCG */ static inline bool memcg_slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru, @@ -2196,18 +2234,37 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p, int objects) { } + +static inline bool memcg_slab_post_charge(void *p, gfp_t flags) +{ + return true; +} #endif /* CONFIG_MEMCG */ +#ifdef CONFIG_SLUB_RCU_DEBUG +static void slab_free_after_rcu_debug(struct rcu_head *rcu_head); + +struct rcu_delayed_free { + struct rcu_head head; + void *object; +}; +#endif + /* * Hooks for other subsystems that check memory allocations. In a typical * production configuration these hooks all should produce no code at all. * * Returns true if freeing of the object can proceed, false if its reuse - * was delayed by KASAN quarantine, or it was returned to KFENCE. + * was delayed by CONFIG_SLUB_RCU_DEBUG or KASAN quarantine, or it was returned + * to KFENCE. */ static __always_inline -bool slab_free_hook(struct kmem_cache *s, void *x, bool init) +bool slab_free_hook(struct kmem_cache *s, void *x, bool init, + bool after_rcu_delay) { + /* Are the object contents still accessible? */ + bool still_accessible = (s->flags & SLAB_TYPESAFE_BY_RCU) && !after_rcu_delay; + kmemleak_free_recursive(x, s->flags); kmsan_slab_free(s, x); @@ -2217,13 +2274,42 @@ bool slab_free_hook(struct kmem_cache *s, void *x, bool init) debug_check_no_obj_freed(x, s->object_size); /* Use KCSAN to help debug racy use-after-free. */ - if (!(s->flags & SLAB_TYPESAFE_BY_RCU)) + if (!still_accessible) __kcsan_check_access(x, s->object_size, KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT); if (kfence_free(x)) return false; + /* + * Give KASAN a chance to notice an invalid free operation before we + * modify the object. + */ + if (kasan_slab_pre_free(s, x)) + return false; + +#ifdef CONFIG_SLUB_RCU_DEBUG + if (still_accessible) { + struct rcu_delayed_free *delayed_free; + + delayed_free = kmalloc(sizeof(*delayed_free), GFP_NOWAIT); + if (delayed_free) { + /* + * Let KASAN track our call stack as a "related work + * creation", just like if the object had been freed + * normally via kfree_rcu(). + * We have to do this manually because the rcu_head is + * not located inside the object. + */ + kasan_record_aux_stack_noalloc(x); + + delayed_free->object = x; + call_rcu(&delayed_free->head, slab_free_after_rcu_debug); + return false; + } + } +#endif /* CONFIG_SLUB_RCU_DEBUG */ + /* * As memory initialization might be integrated into KASAN, * kasan_slab_free and initialization memset's must be @@ -2237,17 +2323,24 @@ bool slab_free_hook(struct kmem_cache *s, void *x, bool init) */ if (unlikely(init)) { int rsize; - unsigned int inuse; + unsigned int inuse, orig_size; inuse = get_info_end(s); + orig_size = get_orig_size(s, x); if (!kasan_has_integrated_init()) - memset(kasan_reset_tag(x), 0, s->object_size); + memset(kasan_reset_tag(x), 0, orig_size); rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad : 0; memset((char *)kasan_reset_tag(x) + inuse, 0, s->size - inuse - rsize); + /* + * Restore orig_size, otherwize kmalloc redzone overwritten + * would be reported + */ + set_orig_size(s, x, orig_size); + } /* KASAN might put x into memory quarantine, delaying its reuse. */ - return !kasan_slab_free(s, x, init); + return !kasan_slab_free(s, x, init, still_accessible); } static __fastpath_inline @@ -2261,7 +2354,7 @@ bool slab_free_freelist_hook(struct kmem_cache *s, void **head, void **tail, bool init; if (is_kfence_address(next)) { - slab_free_hook(s, next, false); + slab_free_hook(s, next, false, false); return false; } @@ -2276,7 +2369,7 @@ bool slab_free_freelist_hook(struct kmem_cache *s, void **head, void **tail, next = get_freepointer(s, object); /* If object's reuse doesn't have to be delayed */ - if (likely(slab_free_hook(s, object, init))) { + if (likely(slab_free_hook(s, object, init, false))) { /* Move object to the new freelist */ set_freepointer(s, object, *head); *head = object; @@ -2316,7 +2409,11 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node, struct slab *slab; unsigned int order = oo_order(oo); - folio = (struct folio *)alloc_pages_node(node, flags, order); + if (node == NUMA_NO_NODE) + folio = (struct folio *)alloc_pages(flags, order); + else + folio = (struct folio *)__alloc_pages_node(node, flags, order); + if (!folio) return NULL; @@ -3414,14 +3511,15 @@ slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid) { static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); + int cpu = raw_smp_processor_id(); int node; struct kmem_cache_node *n; if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs)) return; - pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n", - nid, gfpflags, &gfpflags); + pr_warn("SLUB: Unable to allocate memory on CPU %u (of node %d) on node %d, gfp=%#x(%pGg)\n", + cpu, cpu_to_node(cpu), nid, gfpflags, &gfpflags); pr_warn(" cache: %s, object size: %u, buffer size: %u, default order: %u, min order: %u\n", s->name, s->object_size, s->size, oo_order(s->oo), oo_order(s->min)); @@ -3920,8 +4018,7 @@ static void *__slab_alloc_node(struct kmem_cache *s, * If the object has been wiped upon free, make sure it's fully initialized by * zeroing out freelist pointer. * - * Note that we also wipe custom freelist pointers specified via - * s->rcu_freeptr_offset. + * Note that we also wipe custom freelist pointers. */ static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s, void *obj) @@ -4063,6 +4160,15 @@ void *kmem_cache_alloc_lru_noprof(struct kmem_cache *s, struct list_lru *lru, } EXPORT_SYMBOL(kmem_cache_alloc_lru_noprof); +bool kmem_cache_charge(void *objp, gfp_t gfpflags) +{ + if (!memcg_kmem_online()) + return true; + + return memcg_slab_post_charge(objp, gfpflags); +} +EXPORT_SYMBOL(kmem_cache_charge); + /** * kmem_cache_alloc_node - Allocate an object on the specified node * @s: The cache to allocate from. @@ -4471,7 +4577,7 @@ void slab_free(struct kmem_cache *s, struct slab *slab, void *object, memcg_slab_free_hook(s, slab, &object, 1); alloc_tagging_slab_free_hook(s, slab, &object, 1); - if (likely(slab_free_hook(s, object, slab_want_init_on_free(s)))) + if (likely(slab_free_hook(s, object, slab_want_init_on_free(s), false))) do_slab_free(s, slab, object, object, 1, addr); } @@ -4480,7 +4586,7 @@ void slab_free(struct kmem_cache *s, struct slab *slab, void *object, static noinline void memcg_alloc_abort_single(struct kmem_cache *s, void *object) { - if (likely(slab_free_hook(s, object, slab_want_init_on_free(s)))) + if (likely(slab_free_hook(s, object, slab_want_init_on_free(s), false))) do_slab_free(s, virt_to_slab(object), object, object, 1, _RET_IP_); } #endif @@ -4499,6 +4605,33 @@ void slab_free_bulk(struct kmem_cache *s, struct slab *slab, void *head, do_slab_free(s, slab, head, tail, cnt, addr); } +#ifdef CONFIG_SLUB_RCU_DEBUG +static void slab_free_after_rcu_debug(struct rcu_head *rcu_head) +{ + struct rcu_delayed_free *delayed_free = + container_of(rcu_head, struct rcu_delayed_free, head); + void *object = delayed_free->object; + struct slab *slab = virt_to_slab(object); + struct kmem_cache *s; + + kfree(delayed_free); + + if (WARN_ON(is_kfence_address(object))) + return; + + /* find the object and the cache again */ + if (WARN_ON(!slab)) + return; + s = slab->slab_cache; + if (WARN_ON(!(s->flags & SLAB_TYPESAFE_BY_RCU))) + return; + + /* resume freeing */ + if (slab_free_hook(s, object, slab_want_init_on_free(s), true)) + do_slab_free(s, slab, object, object, 1, _THIS_IP_); +} +#endif /* CONFIG_SLUB_RCU_DEBUG */ + #ifdef CONFIG_KASAN_GENERIC void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr) { @@ -5145,17 +5278,11 @@ static void set_cpu_partial(struct kmem_cache *s) #endif } -/* Was a valid freeptr offset requested? */ -static inline bool has_freeptr_offset(const struct kmem_cache *s) -{ - return s->rcu_freeptr_offset != UINT_MAX; -} - /* * calculate_sizes() determines the order and the distribution of data within * a slab object. */ -static int calculate_sizes(struct kmem_cache *s) +static int calculate_sizes(struct kmem_cache_args *args, struct kmem_cache *s) { slab_flags_t flags = s->flags; unsigned int size = s->object_size; @@ -5196,7 +5323,7 @@ static int calculate_sizes(struct kmem_cache *s) */ s->inuse = size; - if (((flags & SLAB_TYPESAFE_BY_RCU) && !has_freeptr_offset(s)) || + if (((flags & SLAB_TYPESAFE_BY_RCU) && !args->use_freeptr_offset) || (flags & SLAB_POISON) || s->ctor || ((flags & SLAB_RED_ZONE) && (s->object_size < sizeof(void *) || slub_debug_orig_size(s)))) { @@ -5218,8 +5345,8 @@ static int calculate_sizes(struct kmem_cache *s) */ s->offset = size; size += sizeof(void *); - } else if ((flags & SLAB_TYPESAFE_BY_RCU) && has_freeptr_offset(s)) { - s->offset = s->rcu_freeptr_offset; + } else if ((flags & SLAB_TYPESAFE_BY_RCU) && args->use_freeptr_offset) { + s->offset = args->freeptr_offset; } else { /* * Store freelist pointer near middle of object to keep @@ -5294,65 +5421,6 @@ static int calculate_sizes(struct kmem_cache *s) return !!oo_objects(s->oo); } -static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags) -{ - s->flags = kmem_cache_flags(flags, s->name); -#ifdef CONFIG_SLAB_FREELIST_HARDENED - s->random = get_random_long(); -#endif - - if (!calculate_sizes(s)) - goto error; - if (disable_higher_order_debug) { - /* - * Disable debugging flags that store metadata if the min slab - * order increased. - */ - if (get_order(s->size) > get_order(s->object_size)) { - s->flags &= ~DEBUG_METADATA_FLAGS; - s->offset = 0; - if (!calculate_sizes(s)) - goto error; - } - } - -#ifdef system_has_freelist_aba - if (system_has_freelist_aba() && !(s->flags & SLAB_NO_CMPXCHG)) { - /* Enable fast mode */ - s->flags |= __CMPXCHG_DOUBLE; - } -#endif - - /* - * The larger the object size is, the more slabs we want on the partial - * list to avoid pounding the page allocator excessively. - */ - s->min_partial = min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2); - s->min_partial = max_t(unsigned long, MIN_PARTIAL, s->min_partial); - - set_cpu_partial(s); - -#ifdef CONFIG_NUMA - s->remote_node_defrag_ratio = 1000; -#endif - - /* Initialize the pre-computed randomized freelist if slab is up */ - if (slab_state >= UP) { - if (init_cache_random_seq(s)) - goto error; - } - - if (!init_kmem_cache_nodes(s)) - goto error; - - if (alloc_kmem_cache_cpus(s)) - return 0; - -error: - __kmem_cache_release(s); - return -EINVAL; -} - static void list_slab_objects(struct kmem_cache *s, struct slab *slab, const char *text) { @@ -5906,28 +5974,90 @@ __kmem_cache_alias(const char *name, unsigned int size, unsigned int align, return s; } -int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags) +int do_kmem_cache_create(struct kmem_cache *s, const char *name, + unsigned int size, struct kmem_cache_args *args, + slab_flags_t flags) { - int err; + int err = -EINVAL; - err = kmem_cache_open(s, flags); - if (err) - return err; + s->name = name; + s->size = s->object_size = size; + + s->flags = kmem_cache_flags(flags, s->name); +#ifdef CONFIG_SLAB_FREELIST_HARDENED + s->random = get_random_long(); +#endif + s->align = args->align; + s->ctor = args->ctor; +#ifdef CONFIG_HARDENED_USERCOPY + s->useroffset = args->useroffset; + s->usersize = args->usersize; +#endif + + if (!calculate_sizes(args, s)) + goto out; + if (disable_higher_order_debug) { + /* + * Disable debugging flags that store metadata if the min slab + * order increased. + */ + if (get_order(s->size) > get_order(s->object_size)) { + s->flags &= ~DEBUG_METADATA_FLAGS; + s->offset = 0; + if (!calculate_sizes(args, s)) + goto out; + } + } + +#ifdef system_has_freelist_aba + if (system_has_freelist_aba() && !(s->flags & SLAB_NO_CMPXCHG)) { + /* Enable fast mode */ + s->flags |= __CMPXCHG_DOUBLE; + } +#endif + + /* + * The larger the object size is, the more slabs we want on the partial + * list to avoid pounding the page allocator excessively. + */ + s->min_partial = min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2); + s->min_partial = max_t(unsigned long, MIN_PARTIAL, s->min_partial); + + set_cpu_partial(s); + +#ifdef CONFIG_NUMA + s->remote_node_defrag_ratio = 1000; +#endif + + /* Initialize the pre-computed randomized freelist if slab is up */ + if (slab_state >= UP) { + if (init_cache_random_seq(s)) + goto out; + } + + if (!init_kmem_cache_nodes(s)) + goto out; + + if (!alloc_kmem_cache_cpus(s)) + goto out; /* Mutex is not taken during early boot */ - if (slab_state <= UP) - return 0; + if (slab_state <= UP) { + err = 0; + goto out; + } err = sysfs_slab_add(s); - if (err) { - __kmem_cache_release(s); - return err; - } + if (err) + goto out; if (s->flags & SLAB_STORE_USER) debugfs_slab_add(s); - return 0; +out: + if (err) + __kmem_cache_release(s); + return err; } #ifdef SLAB_SUPPORTS_SYSFS diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index ce4d77f49243..2c5632d4fddb 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -714,6 +714,7 @@ struct sock *inet_csk_accept(struct sock *sk, struct proto_accept_arg *arg) out: release_sock(sk); if (newsk && mem_cgroup_sockets_enabled) { + gfp_t gfp = GFP_KERNEL | __GFP_NOFAIL; int amt = 0; /* atomically get the memory usage, set and charge the @@ -731,8 +732,8 @@ out: } if (amt) - mem_cgroup_charge_skmem(newsk->sk_memcg, amt, - GFP_KERNEL | __GFP_NOFAIL); + mem_cgroup_charge_skmem(newsk->sk_memcg, amt, gfp); + kmem_cache_charge(newsk, gfp); release_sock(newsk); }