diff options
Diffstat (limited to 'mm/kasan')
| -rw-r--r-- | mm/kasan/Makefile | 3 | ||||
| -rw-r--r-- | mm/kasan/kasan.c | 356 | ||||
| -rw-r--r-- | mm/kasan/kasan.h | 51 | ||||
| -rw-r--r-- | mm/kasan/quarantine.c | 328 | ||||
| -rw-r--r-- | mm/kasan/report.c | 262 |
5 files changed, 893 insertions, 107 deletions
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile index 64710148941e..e1100433cefe 100644 --- a/mm/kasan/Makefile +++ b/mm/kasan/Makefile @@ -1,8 +1,9 @@ KASAN_SANITIZE := n +KCOV_INSTRUMENT := n CFLAGS_REMOVE_kasan.o = -pg # Function splitter causes unnecessary splits in __asan_load1/__asan_store1 # see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533 CFLAGS_kasan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -obj-y := kasan.o report.o kasan_init.o +obj-y := kasan.o report.o kasan_init.o quarantine.o diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c index ba9adce1422a..eeaaac0fb24a 100644 --- a/mm/kasan/kasan.c +++ b/mm/kasan/kasan.c @@ -17,9 +17,12 @@ #define DISABLE_BRANCH_PROFILING #include <linux/export.h> +#include <linux/interrupt.h> #include <linux/init.h> +#include <linux/kasan.h> #include <linux/kernel.h> #include <linux/kmemleak.h> +#include <linux/linkage.h> #include <linux/memblock.h> #include <linux/memory.h> #include <linux/mm.h> @@ -31,11 +34,21 @@ #include <linux/string.h> #include <linux/types.h> #include <linux/vmalloc.h> -#include <linux/kasan.h> +#include <linux/bug.h> #include "kasan.h" #include "../slab.h" +void kasan_enable_current(void) +{ + current->kasan_depth++; +} + +void kasan_disable_current(void) +{ + current->kasan_depth--; +} + /* * Poisons the shadow memory for 'size' bytes starting from 'addr'. * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE. @@ -60,6 +73,47 @@ void kasan_unpoison_shadow(const void *address, size_t size) } } +static void __kasan_unpoison_stack(struct task_struct *task, const void *sp) +{ + void *base = task_stack_page(task); + size_t size = sp - base; + + kasan_unpoison_shadow(base, size); +} + +/* Unpoison the entire stack for a task. */ +void kasan_unpoison_task_stack(struct task_struct *task) +{ + __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE); +} + +/* Unpoison the stack for the current task beyond a watermark sp value. */ +asmlinkage void kasan_unpoison_task_stack_below(const void *watermark) +{ + /* + * Calculate the task stack base address. Avoid using 'current' + * because this function is called by early resume code which hasn't + * yet set up the percpu register (%gs). + */ + void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1)); + + kasan_unpoison_shadow(base, watermark - base); +} + +/* + * Clear all poison for the region between the current SP and a provided + * watermark value, as is sometimes required prior to hand-crafted asm function + * returns in the middle of functions. + */ +void kasan_unpoison_stack_above_sp_to(const void *watermark) +{ + const void *sp = __builtin_frame_address(0); + size_t size = watermark - sp; + + if (WARN_ON(sp > watermark)) + return; + kasan_unpoison_shadow(sp, size); +} /* * All functions below always inlined so compiler could @@ -252,32 +306,48 @@ static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size) return memory_is_poisoned_n(addr, size); } - -static __always_inline void check_memory_region(unsigned long addr, - size_t size, bool write) +static __always_inline void check_memory_region_inline(unsigned long addr, + size_t size, bool write, + unsigned long ret_ip) { if (unlikely(size == 0)) return; if (unlikely((void *)addr < kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { - kasan_report(addr, size, write, _RET_IP_); + kasan_report(addr, size, write, ret_ip); return; } if (likely(!memory_is_poisoned(addr, size))) return; - kasan_report(addr, size, write, _RET_IP_); + kasan_report(addr, size, write, ret_ip); } -void __asan_loadN(unsigned long addr, size_t size); -void __asan_storeN(unsigned long addr, size_t size); +static void check_memory_region(unsigned long addr, + size_t size, bool write, + unsigned long ret_ip) +{ + check_memory_region_inline(addr, size, write, ret_ip); +} + +void kasan_check_read(const void *p, unsigned int size) +{ + check_memory_region((unsigned long)p, size, false, _RET_IP_); +} +EXPORT_SYMBOL(kasan_check_read); + +void kasan_check_write(const void *p, unsigned int size) +{ + check_memory_region((unsigned long)p, size, true, _RET_IP_); +} +EXPORT_SYMBOL(kasan_check_write); #undef memset void *memset(void *addr, int c, size_t len) { - __asan_storeN((unsigned long)addr, len); + check_memory_region((unsigned long)addr, len, true, _RET_IP_); return __memset(addr, c, len); } @@ -285,8 +355,8 @@ void *memset(void *addr, int c, size_t len) #undef memmove void *memmove(void *dest, const void *src, size_t len) { - __asan_loadN((unsigned long)src, len); - __asan_storeN((unsigned long)dest, len); + check_memory_region((unsigned long)src, len, false, _RET_IP_); + check_memory_region((unsigned long)dest, len, true, _RET_IP_); return __memmove(dest, src, len); } @@ -294,8 +364,8 @@ void *memmove(void *dest, const void *src, size_t len) #undef memcpy void *memcpy(void *dest, const void *src, size_t len) { - __asan_loadN((unsigned long)src, len); - __asan_storeN((unsigned long)dest, len); + check_memory_region((unsigned long)src, len, false, _RET_IP_); + check_memory_region((unsigned long)dest, len, true, _RET_IP_); return __memcpy(dest, src, len); } @@ -314,6 +384,80 @@ void kasan_free_pages(struct page *page, unsigned int order) KASAN_FREE_PAGE); } +/* + * Adaptive redzone policy taken from the userspace AddressSanitizer runtime. + * For larger allocations larger redzones are used. + */ +static size_t optimal_redzone(size_t object_size) +{ + int rz = + object_size <= 64 - 16 ? 16 : + object_size <= 128 - 32 ? 32 : + object_size <= 512 - 64 ? 64 : + object_size <= 4096 - 128 ? 128 : + object_size <= (1 << 14) - 256 ? 256 : + object_size <= (1 << 15) - 512 ? 512 : + object_size <= (1 << 16) - 1024 ? 1024 : 2048; + return rz; +} + +void kasan_cache_create(struct kmem_cache *cache, size_t *size, + unsigned long *flags) +{ + int redzone_adjust; + int orig_size = *size; + + /* Add alloc meta. */ + cache->kasan_info.alloc_meta_offset = *size; + *size += sizeof(struct kasan_alloc_meta); + + /* Add free meta. */ + if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor || + cache->object_size < sizeof(struct kasan_free_meta)) { + cache->kasan_info.free_meta_offset = *size; + *size += sizeof(struct kasan_free_meta); + } + redzone_adjust = optimal_redzone(cache->object_size) - + (*size - cache->object_size); + + if (redzone_adjust > 0) + *size += redzone_adjust; + + *size = min(KMALLOC_MAX_SIZE, max(*size, cache->object_size + + optimal_redzone(cache->object_size))); + + /* + * If the metadata doesn't fit, don't enable KASAN at all. + */ + if (*size <= cache->kasan_info.alloc_meta_offset || + *size <= cache->kasan_info.free_meta_offset) { + cache->kasan_info.alloc_meta_offset = 0; + cache->kasan_info.free_meta_offset = 0; + *size = orig_size; + return; + } + + *flags |= SLAB_KASAN; +} + +void kasan_cache_shrink(struct kmem_cache *cache) +{ + quarantine_remove_cache(cache); +} + +void kasan_cache_shutdown(struct kmem_cache *cache) +{ + quarantine_remove_cache(cache); +} + +size_t kasan_metadata_size(struct kmem_cache *cache) +{ + return (cache->kasan_info.alloc_meta_offset ? + sizeof(struct kasan_alloc_meta) : 0) + + (cache->kasan_info.free_meta_offset ? + sizeof(struct kasan_free_meta) : 0); +} + void kasan_poison_slab(struct page *page) { kasan_poison_shadow(page_address(page), @@ -333,12 +477,84 @@ void kasan_poison_object_data(struct kmem_cache *cache, void *object) KASAN_KMALLOC_REDZONE); } -void kasan_slab_alloc(struct kmem_cache *cache, void *object) +static inline int in_irqentry_text(unsigned long ptr) { - kasan_kmalloc(cache, object, cache->object_size); + return (ptr >= (unsigned long)&__irqentry_text_start && + ptr < (unsigned long)&__irqentry_text_end) || + (ptr >= (unsigned long)&__softirqentry_text_start && + ptr < (unsigned long)&__softirqentry_text_end); } -void kasan_slab_free(struct kmem_cache *cache, void *object) +static inline void filter_irq_stacks(struct stack_trace *trace) +{ + int i; + + if (!trace->nr_entries) + return; + for (i = 0; i < trace->nr_entries; i++) + if (in_irqentry_text(trace->entries[i])) { + /* Include the irqentry function into the stack. */ + trace->nr_entries = i + 1; + break; + } +} + +static inline depot_stack_handle_t save_stack(gfp_t flags) +{ + unsigned long entries[KASAN_STACK_DEPTH]; + struct stack_trace trace = { + .nr_entries = 0, + .entries = entries, + .max_entries = KASAN_STACK_DEPTH, + .skip = 0 + }; + + save_stack_trace(&trace); + filter_irq_stacks(&trace); + if (trace.nr_entries != 0 && + trace.entries[trace.nr_entries-1] == ULONG_MAX) + trace.nr_entries--; + + return depot_save_stack(&trace, flags); +} + +static inline void set_track(struct kasan_track *track, gfp_t flags) +{ + track->pid = current->pid; + track->stack = save_stack(flags); +} + +struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache, + const void *object) +{ + BUILD_BUG_ON(sizeof(struct kasan_alloc_meta) > 32); + return (void *)object + cache->kasan_info.alloc_meta_offset; +} + +struct kasan_free_meta *get_free_info(struct kmem_cache *cache, + const void *object) +{ + BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32); + return (void *)object + cache->kasan_info.free_meta_offset; +} + +void kasan_init_slab_obj(struct kmem_cache *cache, const void *object) +{ + struct kasan_alloc_meta *alloc_info; + + if (!(cache->flags & SLAB_KASAN)) + return; + + alloc_info = get_alloc_info(cache, object); + __memset(alloc_info, 0, sizeof(*alloc_info)); +} + +void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags) +{ + kasan_kmalloc(cache, object, cache->object_size, flags); +} + +static void kasan_poison_slab_free(struct kmem_cache *cache, void *object) { unsigned long size = cache->object_size; unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE); @@ -350,11 +566,40 @@ void kasan_slab_free(struct kmem_cache *cache, void *object) kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE); } -void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size) +bool kasan_slab_free(struct kmem_cache *cache, void *object) +{ + s8 shadow_byte; + + /* RCU slabs could be legally used after free within the RCU period */ + if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU)) + return false; + + shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object)); + if (shadow_byte < 0 || shadow_byte >= KASAN_SHADOW_SCALE_SIZE) { + kasan_report_double_free(cache, object, + __builtin_return_address(1)); + return true; + } + + kasan_poison_slab_free(cache, object); + + if (unlikely(!(cache->flags & SLAB_KASAN))) + return false; + + set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT); + quarantine_put(get_free_info(cache, object), cache); + return true; +} + +void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size, + gfp_t flags) { unsigned long redzone_start; unsigned long redzone_end; + if (gfpflags_allow_blocking(flags)) + quarantine_reduce(); + if (unlikely(object == NULL)) return; @@ -366,15 +611,21 @@ void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size) kasan_unpoison_shadow(object, size); kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, KASAN_KMALLOC_REDZONE); + + if (cache->flags & SLAB_KASAN) + set_track(&get_alloc_info(cache, object)->alloc_track, flags); } EXPORT_SYMBOL(kasan_kmalloc); -void kasan_kmalloc_large(const void *ptr, size_t size) +void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags) { struct page *page; unsigned long redzone_start; unsigned long redzone_end; + if (gfpflags_allow_blocking(flags)) + quarantine_reduce(); + if (unlikely(ptr == NULL)) return; @@ -388,7 +639,7 @@ void kasan_kmalloc_large(const void *ptr, size_t size) KASAN_PAGE_REDZONE); } -void kasan_krealloc(const void *object, size_t size) +void kasan_krealloc(const void *object, size_t size, gfp_t flags) { struct page *page; @@ -398,12 +649,12 @@ void kasan_krealloc(const void *object, size_t size) page = virt_to_head_page(object); if (unlikely(!PageSlab(page))) - kasan_kmalloc_large(object, size); + kasan_kmalloc_large(object, size, flags); else - kasan_kmalloc(page->slab_cache, object, size); + kasan_kmalloc(page->slab_cache, object, size, flags); } -void kasan_kfree(void *ptr) +void kasan_poison_kfree(void *ptr) { struct page *page; @@ -413,7 +664,7 @@ void kasan_kfree(void *ptr) kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page), KASAN_FREE_PAGE); else - kasan_slab_free(page->slab_cache, ptr); + kasan_poison_slab_free(page->slab_cache, ptr); } void kasan_kfree_large(const void *ptr) @@ -483,22 +734,22 @@ void __asan_unregister_globals(struct kasan_global *globals, size_t size) } EXPORT_SYMBOL(__asan_unregister_globals); -#define DEFINE_ASAN_LOAD_STORE(size) \ - void __asan_load##size(unsigned long addr) \ - { \ - check_memory_region(addr, size, false); \ - } \ - EXPORT_SYMBOL(__asan_load##size); \ - __alias(__asan_load##size) \ - void __asan_load##size##_noabort(unsigned long); \ - EXPORT_SYMBOL(__asan_load##size##_noabort); \ - void __asan_store##size(unsigned long addr) \ - { \ - check_memory_region(addr, size, true); \ - } \ - EXPORT_SYMBOL(__asan_store##size); \ - __alias(__asan_store##size) \ - void __asan_store##size##_noabort(unsigned long); \ +#define DEFINE_ASAN_LOAD_STORE(size) \ + void __asan_load##size(unsigned long addr) \ + { \ + check_memory_region_inline(addr, size, false, _RET_IP_);\ + } \ + EXPORT_SYMBOL(__asan_load##size); \ + __alias(__asan_load##size) \ + void __asan_load##size##_noabort(unsigned long); \ + EXPORT_SYMBOL(__asan_load##size##_noabort); \ + void __asan_store##size(unsigned long addr) \ + { \ + check_memory_region_inline(addr, size, true, _RET_IP_); \ + } \ + EXPORT_SYMBOL(__asan_store##size); \ + __alias(__asan_store##size) \ + void __asan_store##size##_noabort(unsigned long); \ EXPORT_SYMBOL(__asan_store##size##_noabort) DEFINE_ASAN_LOAD_STORE(1); @@ -509,7 +760,7 @@ DEFINE_ASAN_LOAD_STORE(16); void __asan_loadN(unsigned long addr, size_t size) { - check_memory_region(addr, size, false); + check_memory_region(addr, size, false, _RET_IP_); } EXPORT_SYMBOL(__asan_loadN); @@ -519,7 +770,7 @@ EXPORT_SYMBOL(__asan_loadN_noabort); void __asan_storeN(unsigned long addr, size_t size) { - check_memory_region(addr, size, true); + check_memory_region(addr, size, true, _RET_IP_); } EXPORT_SYMBOL(__asan_storeN); @@ -531,6 +782,25 @@ EXPORT_SYMBOL(__asan_storeN_noabort); void __asan_handle_no_return(void) {} EXPORT_SYMBOL(__asan_handle_no_return); +/* Emitted by compiler to poison large objects when they go out of scope. */ +void __asan_poison_stack_memory(const void *addr, size_t size) +{ + /* + * Addr is KASAN_SHADOW_SCALE_SIZE-aligned and the object is surrounded + * by redzones, so we simply round up size to simplify logic. + */ + kasan_poison_shadow(addr, round_up(size, KASAN_SHADOW_SCALE_SIZE), + KASAN_USE_AFTER_SCOPE); +} +EXPORT_SYMBOL(__asan_poison_stack_memory); + +/* Emitted by compiler to unpoison large objects when they go into scope. */ +void __asan_unpoison_stack_memory(const void *addr, size_t size) +{ + kasan_unpoison_shadow(addr, size); +} +EXPORT_SYMBOL(__asan_unpoison_stack_memory); + #ifdef CONFIG_MEMORY_HOTPLUG static int kasan_mem_notifier(struct notifier_block *nb, unsigned long action, void *data) @@ -540,8 +810,8 @@ static int kasan_mem_notifier(struct notifier_block *nb, static int __init kasan_memhotplug_init(void) { - pr_err("WARNING: KASAN doesn't support memory hot-add\n"); - pr_err("Memory hot-add will be disabled\n"); + pr_info("WARNING: KASAN doesn't support memory hot-add\n"); + pr_info("Memory hot-add will be disabled\n"); hotplug_memory_notifier(kasan_mem_notifier, 0); diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 37ff0ab6a8ff..1229298cce64 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -2,6 +2,7 @@ #define __MM_KASAN_KASAN_H #include <linux/kasan.h> +#include <linux/stackdepot.h> #define KASAN_SHADOW_SCALE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT) #define KASAN_SHADOW_MASK (KASAN_SHADOW_SCALE_SIZE - 1) @@ -20,6 +21,7 @@ #define KASAN_STACK_MID 0xF2 #define KASAN_STACK_RIGHT 0xF3 #define KASAN_STACK_PARTIAL 0xF4 +#define KASAN_USE_AFTER_SCOPE 0xF8 /* Don't break randconfig/all*config builds */ #ifndef KASAN_ABI_VERSION @@ -57,18 +59,57 @@ struct kasan_global { #endif }; +/** + * Structures to keep alloc and free tracks * + */ + +#define KASAN_STACK_DEPTH 64 + +struct kasan_track { + u32 pid; + depot_stack_handle_t stack; +}; + +struct kasan_alloc_meta { + struct kasan_track alloc_track; + struct kasan_track free_track; +}; + +struct qlist_node { + struct qlist_node *next; +}; +struct kasan_free_meta { + /* This field is used while the object is in the quarantine. + * Otherwise it might be used for the allocator freelist. + */ + struct qlist_node quarantine_link; +}; + +struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache, + const void *object); +struct kasan_free_meta *get_free_info(struct kmem_cache *cache, + const void *object); + static inline const void *kasan_shadow_to_mem(const void *shadow_addr) { return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT); } -static inline bool kasan_report_enabled(void) -{ - return !current->kasan_depth; -} - void kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip); +void kasan_report_double_free(struct kmem_cache *cache, void *object, + void *ip); + +#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB) +void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache); +void quarantine_reduce(void); +void quarantine_remove_cache(struct kmem_cache *cache); +#else +static inline void quarantine_put(struct kasan_free_meta *info, + struct kmem_cache *cache) { } +static inline void quarantine_reduce(void) { } +static inline void quarantine_remove_cache(struct kmem_cache *cache) { } +#endif #endif diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c new file mode 100644 index 000000000000..3a8ddf8baf7d --- /dev/null +++ b/mm/kasan/quarantine.c @@ -0,0 +1,328 @@ +/* + * KASAN quarantine. + * + * Author: Alexander Potapenko <glider@google.com> + * Copyright (C) 2016 Google, Inc. + * + * Based on code by Dmitry Chernenkov. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * version 2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + */ + +#include <linux/gfp.h> +#include <linux/hash.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/percpu.h> +#include <linux/printk.h> +#include <linux/shrinker.h> +#include <linux/slab.h> +#include <linux/srcu.h> +#include <linux/string.h> +#include <linux/types.h> + +#include "../slab.h" +#include "kasan.h" + +/* Data structure and operations for quarantine queues. */ + +/* + * Each queue is a signle-linked list, which also stores the total size of + * objects inside of it. + */ +struct qlist_head { + struct qlist_node *head; + struct qlist_node *tail; + size_t bytes; +}; + +#define QLIST_INIT { NULL, NULL, 0 } + +static bool qlist_empty(struct qlist_head *q) +{ + return !q->head; +} + +static void qlist_init(struct qlist_head *q) +{ + q->head = q->tail = NULL; + q->bytes = 0; +} + +static void qlist_put(struct qlist_head *q, struct qlist_node *qlink, + size_t size) +{ + if (unlikely(qlist_empty(q))) + q->head = qlink; + else + q->tail->next = qlink; + q->tail = qlink; + qlink->next = NULL; + q->bytes += size; +} + +static void qlist_move_all(struct qlist_head *from, struct qlist_head *to) +{ + if (unlikely(qlist_empty(from))) + return; + + if (qlist_empty(to)) { + *to = *from; + qlist_init(from); + return; + } + + to->tail->next = from->head; + to->tail = from->tail; + to->bytes += from->bytes; + + qlist_init(from); +} + +#define QUARANTINE_PERCPU_SIZE (1 << 20) +#define QUARANTINE_BATCHES \ + (1024 > 4 * CONFIG_NR_CPUS ? 1024 : 4 * CONFIG_NR_CPUS) + +/* + * The object quarantine consists of per-cpu queues and a global queue, + * guarded by quarantine_lock. + */ +static DEFINE_PER_CPU(struct qlist_head, cpu_quarantine); + +/* Round-robin FIFO array of batches. */ +static struct qlist_head global_quarantine[QUARANTINE_BATCHES]; +static int quarantine_head; +static int quarantine_tail; +/* Total size of all objects in global_quarantine across all batches. */ +static unsigned long quarantine_size; +static DEFINE_SPINLOCK(quarantine_lock); +DEFINE_STATIC_SRCU(remove_cache_srcu); + +/* Maximum size of the global queue. */ +static unsigned long quarantine_max_size; + +/* + * Target size of a batch in global_quarantine. + * Usually equal to QUARANTINE_PERCPU_SIZE unless we have too much RAM. + */ +static unsigned long quarantine_batch_size; + +/* + * The fraction of physical memory the quarantine is allowed to occupy. + * Quarantine doesn't support memory shrinker with SLAB allocator, so we keep + * the ratio low to avoid OOM. + */ +#define QUARANTINE_FRACTION 32 + +static struct kmem_cache *qlink_to_cache(struct qlist_node *qlink) +{ + return virt_to_head_page(qlink)->slab_cache; +} + +static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache) +{ + struct kasan_free_meta *free_info = + container_of(qlink, struct kasan_free_meta, + quarantine_link); + + return ((void *)free_info) - cache->kasan_info.free_meta_offset; +} + +static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache) +{ + void *object = qlink_to_object(qlink, cache); + unsigned long flags; + + if (IS_ENABLED(CONFIG_SLAB)) + local_irq_save(flags); + + ___cache_free(cache, object, _THIS_IP_); + + if (IS_ENABLED(CONFIG_SLAB)) + local_irq_restore(flags); +} + +static void qlist_free_all(struct qlist_head *q, struct kmem_cache *cache) +{ + struct qlist_node *qlink; + + if (unlikely(qlist_empty(q))) + return; + + qlink = q->head; + while (qlink) { + struct kmem_cache *obj_cache = + cache ? cache : qlink_to_cache(qlink); + struct qlist_node *next = qlink->next; + + qlink_free(qlink, obj_cache); + qlink = next; + } + qlist_init(q); +} + +void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache) +{ + unsigned long flags; + struct qlist_head *q; + struct qlist_head temp = QLIST_INIT; + + /* + * Note: irq must be disabled until after we move the batch to the + * global quarantine. Otherwise quarantine_remove_cache() can miss + * some objects belonging to the cache if they are in our local temp + * list. quarantine_remove_cache() executes on_each_cpu() at the + * beginning which ensures that it either sees the objects in per-cpu + * lists or in the global quarantine. + */ + local_irq_save(flags); + + q = this_cpu_ptr(&cpu_quarantine); + qlist_put(q, &info->quarantine_link, cache->size); + if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE)) { + qlist_move_all(q, &temp); + + spin_lock(&quarantine_lock); + WRITE_ONCE(quarantine_size, quarantine_size + temp.bytes); + qlist_move_all(&temp, &global_quarantine[quarantine_tail]); + if (global_quarantine[quarantine_tail].bytes >= + READ_ONCE(quarantine_batch_size)) { + int new_tail; + + new_tail = quarantine_tail + 1; + if (new_tail == QUARANTINE_BATCHES) + new_tail = 0; + if (new_tail != quarantine_head) + quarantine_tail = new_tail; + } + spin_unlock(&quarantine_lock); + } + + local_irq_restore(flags); +} + +void quarantine_reduce(void) +{ + size_t total_size, new_quarantine_size, percpu_quarantines; + unsigned long flags; + int srcu_idx; + struct qlist_head to_free = QLIST_INIT; + + if (likely(READ_ONCE(quarantine_size) <= + READ_ONCE(quarantine_max_size))) + return; + + /* + * srcu critical section ensures that quarantine_remove_cache() + * will not miss objects belonging to the cache while they are in our + * local to_free list. srcu is chosen because (1) it gives us private + * grace period domain that does not interfere with anything else, + * and (2) it allows synchronize_srcu() to return without waiting + * if there are no pending read critical sections (which is the + * expected case). + */ + srcu_idx = srcu_read_lock(&remove_cache_srcu); + spin_lock_irqsave(&quarantine_lock, flags); + + /* + * Update quarantine size in case of hotplug. Allocate a fraction of + * the installed memory to quarantine minus per-cpu queue limits. + */ + total_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) / + QUARANTINE_FRACTION; + percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus(); + new_quarantine_size = (total_size < percpu_quarantines) ? + 0 : total_size - percpu_quarantines; + WRITE_ONCE(quarantine_max_size, new_quarantine_size); + /* Aim at consuming at most 1/2 of slots in quarantine. */ + WRITE_ONCE(quarantine_batch_size, max((size_t)QUARANTINE_PERCPU_SIZE, + 2 * total_size / QUARANTINE_BATCHES)); + + if (likely(quarantine_size > quarantine_max_size)) { + qlist_move_all(&global_quarantine[quarantine_head], &to_free); + WRITE_ONCE(quarantine_size, quarantine_size - to_free.bytes); + quarantine_head++; + if (quarantine_head == QUARANTINE_BATCHES) + quarantine_head = 0; + } + + spin_unlock_irqrestore(&quarantine_lock, flags); + + qlist_free_all(&to_free, NULL); + srcu_read_unlock(&remove_cache_srcu, srcu_idx); +} + +static void qlist_move_cache(struct qlist_head *from, + struct qlist_head *to, + struct kmem_cache *cache) +{ + struct qlist_node *curr; + + if (unlikely(qlist_empty(from))) + return; + + curr = from->head; + qlist_init(from); + while (curr) { + struct qlist_node *next = curr->next; + struct kmem_cache *obj_cache = qlink_to_cache(curr); + + if (obj_cache == cache) + qlist_put(to, curr, obj_cache->size); + else + qlist_put(from, curr, obj_cache->size); + + curr = next; + } +} + +static void per_cpu_remove_cache(void *arg) +{ + struct kmem_cache *cache = arg; + struct qlist_head to_free = QLIST_INIT; + struct qlist_head *q; + + q = this_cpu_ptr(&cpu_quarantine); + qlist_move_cache(q, &to_free, cache); + qlist_free_all(&to_free, cache); +} + +/* Free all quarantined objects belonging to cache. */ +void quarantine_remove_cache(struct kmem_cache *cache) +{ + unsigned long flags, i; + struct qlist_head to_free = QLIST_INIT; + + /* + * Must be careful to not miss any objects that are being moved from + * per-cpu list to the global quarantine in quarantine_put(), + * nor objects being freed in quarantine_reduce(). on_each_cpu() + * achieves the first goal, while synchronize_srcu() achieves the + * second. + */ + on_each_cpu(per_cpu_remove_cache, cache, 1); + + spin_lock_irqsave(&quarantine_lock, flags); + for (i = 0; i < QUARANTINE_BATCHES; i++) { + if (qlist_empty(&global_quarantine[i])) + continue; + qlist_move_cache(&global_quarantine[i], &to_free, cache); + /* Scanning whole quarantine can take a while. */ + spin_unlock_irqrestore(&quarantine_lock, flags); + cond_resched(); + spin_lock_irqsave(&quarantine_lock, flags); + } + spin_unlock_irqrestore(&quarantine_lock, flags); + + qlist_free_all(&to_free, cache); + + synchronize_srcu(&remove_cache_srcu); +} diff --git a/mm/kasan/report.c b/mm/kasan/report.c index b4e31f78ae69..04bb1d3eb9ec 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -13,12 +13,15 @@ * */ +#include <linux/bitops.h> #include <linux/ftrace.h> +#include <linux/init.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/printk.h> #include <linux/sched.h> #include <linux/slab.h> +#include <linux/stackdepot.h> #include <linux/stacktrace.h> #include <linux/string.h> #include <linux/types.h> @@ -48,7 +51,13 @@ static const void *find_first_bad_addr(const void *addr, size_t size) return first_bad_addr; } -static void print_error_description(struct kasan_access_info *info) +static bool addr_has_shadow(struct kasan_access_info *info) +{ + return (info->access_addr >= + kasan_shadow_to_mem((void *)KASAN_SHADOW_START)); +} + +static const char *get_shadow_bug_type(struct kasan_access_info *info) { const char *bug_type = "unknown-crash"; u8 *shadow_addr; @@ -90,14 +99,44 @@ static void print_error_description(struct kasan_access_info *info) case KASAN_KMALLOC_FREE: bug_type = "use-after-free"; break; + case KASAN_USE_AFTER_SCOPE: + bug_type = "use-after-scope"; + break; } - pr_err("BUG: KASAN: %s in %pS at addr %p\n", - bug_type, (void *)info->ip, - info->access_addr); - pr_err("%s of size %zu by task %s/%d\n", - info->is_write ? "Write" : "Read", - info->access_size, current->comm, task_pid_nr(current)); + return bug_type; +} + +static const char *get_wild_bug_type(struct kasan_access_info *info) +{ + const char *bug_type = "unknown-crash"; + + if ((unsigned long)info->access_addr < PAGE_SIZE) + bug_type = "null-ptr-deref"; + else if ((unsigned long)info->access_addr < TASK_SIZE) + bug_type = "user-memory-access"; + else + bug_type = "wild-memory-access"; + + return bug_type; +} + +static const char *get_bug_type(struct kasan_access_info *info) +{ + if (addr_has_shadow(info)) + return get_shadow_bug_type(info); + return get_wild_bug_type(info); +} + +static void print_error_description(struct kasan_access_info *info) +{ + const char *bug_type = get_bug_type(info); + + pr_err("BUG: KASAN: %s in %pS\n", + bug_type, (void *)info->ip); + pr_err("%s of size %zu at addr %p by task %s/%d\n", + info->is_write ? "Write" : "Read", info->access_size, + info->access_addr, current->comm, task_pid_nr(current)); } static inline bool kernel_or_module_addr(const void *addr) @@ -116,39 +155,119 @@ static inline bool init_task_stack_addr(const void *addr) sizeof(init_thread_union.stack)); } -static void print_address_description(struct kasan_access_info *info) +static DEFINE_SPINLOCK(report_lock); + +static void kasan_start_report(unsigned long *flags) +{ + /* + * Make sure we don't end up in loop. + */ + kasan_disable_current(); + spin_lock_irqsave(&report_lock, *flags); + pr_err("==================================================================\n"); +} + +static void kasan_end_report(unsigned long *flags) +{ + pr_err("==================================================================\n"); + add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); + spin_unlock_irqrestore(&report_lock, *flags); + if (panic_on_warn) + panic("panic_on_warn set ...\n"); + kasan_enable_current(); +} + +static void print_track(struct kasan_track *track, const char *prefix) { - const void *addr = info->access_addr; + pr_err("%s by task %u:\n", prefix, track->pid); + if (track->stack) { + struct stack_trace trace; + depot_fetch_stack(track->stack, &trace); + print_stack_trace(&trace, 0); + } else { + pr_err("(stack is not available)\n"); + } +} + +static struct page *addr_to_page(const void *addr) +{ if ((addr >= (void *)PAGE_OFFSET) && - (addr < high_memory)) { - struct page *page = virt_to_head_page(addr); + (addr < high_memory)) + return virt_to_head_page(addr); + return NULL; +} - if (PageSlab(page)) { - void *object; - struct kmem_cache *cache = page->slab_cache; - void *last_object; +static void describe_object_addr(struct kmem_cache *cache, void *object, + const void *addr) +{ + unsigned long access_addr = (unsigned long)addr; + unsigned long object_addr = (unsigned long)object; + const char *rel_type; + int rel_bytes; - object = virt_to_obj(cache, page_address(page), addr); - last_object = page_address(page) + - page->objects * cache->size; + pr_err("The buggy address belongs to the object at %p\n" + " which belongs to the cache %s of size %d\n", + object, cache->name, cache->object_size); - if (unlikely(object > last_object)) - object = last_object; /* we hit into padding */ + if (!addr) + return; - object_err(cache, page, object, - "kasan: bad access detected"); - return; - } - dump_page(page, "kasan: bad access detected"); + if (access_addr < object_addr) { + rel_type = "to the left"; + rel_bytes = object_addr - access_addr; + } else if (access_addr >= object_addr + cache->object_size) { + rel_type = "to the right"; + rel_bytes = access_addr - (object_addr + cache->object_size); + } else { + rel_type = "inside"; + rel_bytes = access_addr - object_addr; } - if (kernel_or_module_addr(addr)) { - if (!init_task_stack_addr(addr)) - pr_err("Address belongs to variable %pS\n", addr); + pr_err("The buggy address is located %d bytes %s of\n" + " %d-byte region [%p, %p)\n", + rel_bytes, rel_type, cache->object_size, (void *)object_addr, + (void *)(object_addr + cache->object_size)); +} + +static void describe_object(struct kmem_cache *cache, void *object, + const void *addr) +{ + struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object); + + if (cache->flags & SLAB_KASAN) { + print_track(&alloc_info->alloc_track, "Allocated"); + pr_err("\n"); + print_track(&alloc_info->free_track, "Freed"); + pr_err("\n"); } + describe_object_addr(cache, object, addr); +} + +static void print_address_description(void *addr) +{ + struct page *page = addr_to_page(addr); + dump_stack(); + pr_err("\n"); + + if (page && PageSlab(page)) { + struct kmem_cache *cache = page->slab_cache; + void *object = nearest_obj(cache, page, addr); + + describe_object(cache, object, addr); + } + + if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) { + pr_err("The buggy address belongs to the variable:\n"); + pr_err(" %pS\n", addr); + } + + if (page) { + pr_err("The buggy address belongs to the page:\n"); + dump_page(page, "kasan: bad access detected"); + } } static bool row_is_guilty(const void *row, const void *guilty) @@ -203,45 +322,72 @@ static void print_shadow_for_address(const void *addr) } } -static DEFINE_SPINLOCK(report_lock); +void kasan_report_double_free(struct kmem_cache *cache, void *object, + void *ip) +{ + unsigned long flags; + + kasan_start_report(&flags); + pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", ip); + pr_err("\n"); + print_address_description(object); + pr_err("\n"); + print_shadow_for_address(object); + kasan_end_report(&flags); +} static void kasan_report_error(struct kasan_access_info *info) { unsigned long flags; - const char *bug_type; - /* - * Make sure we don't end up in loop. - */ - kasan_disable_current(); - spin_lock_irqsave(&report_lock, flags); - pr_err("=================================" - "=================================\n"); - if (info->access_addr < - kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) { - if ((unsigned long)info->access_addr < PAGE_SIZE) - bug_type = "null-ptr-deref"; - else if ((unsigned long)info->access_addr < TASK_SIZE) - bug_type = "user-memory-access"; - else - bug_type = "wild-memory-access"; - pr_err("BUG: KASAN: %s on address %p\n", - bug_type, info->access_addr); - pr_err("%s of size %zu by task %s/%d\n", - info->is_write ? "Write" : "Read", - info->access_size, current->comm, - task_pid_nr(current)); + kasan_start_report(&flags); + + print_error_description(info); + pr_err("\n"); + + if (!addr_has_shadow(info)) { dump_stack(); } else { - print_error_description(info); - print_address_description(info); + print_address_description((void *)info->access_addr); + pr_err("\n"); print_shadow_for_address(info->first_bad_addr); } - pr_err("=================================" - "=================================\n"); - add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); - spin_unlock_irqrestore(&report_lock, flags); - kasan_enable_current(); + + kasan_end_report(&flags); +} + +static unsigned long kasan_flags; + +#define KASAN_BIT_REPORTED 0 +#define KASAN_BIT_MULTI_SHOT 1 + +bool kasan_save_enable_multi_shot(void) +{ + return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); +} +EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot); + +void kasan_restore_multi_shot(bool enabled) +{ + if (!enabled) + clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); +} +EXPORT_SYMBOL_GPL(kasan_restore_multi_shot); + +static int __init kasan_set_multi_shot(char *str) +{ + set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags); + return 1; +} +__setup("kasan_multi_shot", kasan_set_multi_shot); + +static inline bool kasan_report_enabled(void) +{ + if (current->kasan_depth) + return false; + if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) + return true; + return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags); } void kasan_report(unsigned long addr, size_t size, |