| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * This file contains common generic and tag-based KASAN code. |
| * |
| * Copyright (c) 2014 Samsung Electronics Co., Ltd. |
| * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> |
| * |
| * Some code borrowed from https://github.com/xairy/kasan-prototype by |
| * Andrey Konovalov <andreyknvl@gmail.com> |
| * |
| * 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. |
| * |
| */ |
| |
| #include <linux/export.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> |
| #include <linux/module.h> |
| #include <linux/printk.h> |
| #include <linux/sched.h> |
| #include <linux/sched/task_stack.h> |
| #include <linux/slab.h> |
| #include <linux/stacktrace.h> |
| #include <linux/string.h> |
| #include <linux/types.h> |
| #include <linux/vmalloc.h> |
| #include <linux/bug.h> |
| #include <linux/uaccess.h> |
| |
| #include <asm/cacheflush.h> |
| #include <asm/tlbflush.h> |
| |
| #include "kasan.h" |
| #include "../slab.h" |
| |
| static inline depot_stack_handle_t save_stack(gfp_t flags) |
| { |
| unsigned long entries[KASAN_STACK_DEPTH]; |
| unsigned int nr_entries; |
| |
| nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0); |
| nr_entries = filter_irq_stacks(entries, nr_entries); |
| return stack_depot_save(entries, nr_entries, flags); |
| } |
| |
| static inline void set_track(struct kasan_track *track, gfp_t flags) |
| { |
| track->pid = current->pid; |
| track->stack = save_stack(flags); |
| } |
| |
| void kasan_enable_current(void) |
| { |
| current->kasan_depth++; |
| } |
| |
| void kasan_disable_current(void) |
| { |
| current->kasan_depth--; |
| } |
| |
| bool __kasan_check_read(const volatile void *p, unsigned int size) |
| { |
| return check_memory_region((unsigned long)p, size, false, _RET_IP_); |
| } |
| EXPORT_SYMBOL(__kasan_check_read); |
| |
| bool __kasan_check_write(const volatile void *p, unsigned int size) |
| { |
| return 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) |
| { |
| if (!check_memory_region((unsigned long)addr, len, true, _RET_IP_)) |
| return NULL; |
| |
| return __memset(addr, c, len); |
| } |
| |
| #ifdef __HAVE_ARCH_MEMMOVE |
| #undef memmove |
| void *memmove(void *dest, const void *src, size_t len) |
| { |
| if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || |
| !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) |
| return NULL; |
| |
| return __memmove(dest, src, len); |
| } |
| #endif |
| |
| #undef memcpy |
| void *memcpy(void *dest, const void *src, size_t len) |
| { |
| if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || |
| !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) |
| return NULL; |
| |
| return __memcpy(dest, src, len); |
| } |
| |
| /* |
| * Poisons the shadow memory for 'size' bytes starting from 'addr'. |
| * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE. |
| */ |
| void kasan_poison_shadow(const void *address, size_t size, u8 value) |
| { |
| void *shadow_start, *shadow_end; |
| |
| /* |
| * Perform shadow offset calculation based on untagged address, as |
| * some of the callers (e.g. kasan_poison_object_data) pass tagged |
| * addresses to this function. |
| */ |
| address = reset_tag(address); |
| |
| shadow_start = kasan_mem_to_shadow(address); |
| shadow_end = kasan_mem_to_shadow(address + size); |
| |
| __memset(shadow_start, value, shadow_end - shadow_start); |
| } |
| |
| void kasan_unpoison_shadow(const void *address, size_t size) |
| { |
| u8 tag = get_tag(address); |
| |
| /* |
| * Perform shadow offset calculation based on untagged address, as |
| * some of the callers (e.g. kasan_unpoison_object_data) pass tagged |
| * addresses to this function. |
| */ |
| address = reset_tag(address); |
| |
| kasan_poison_shadow(address, size, tag); |
| |
| if (size & KASAN_SHADOW_MASK) { |
| u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); |
| |
| if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) |
| *shadow = tag; |
| else |
| *shadow = size & KASAN_SHADOW_MASK; |
| } |
| } |
| |
| 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); |
| } |
| |
| void kasan_alloc_pages(struct page *page, unsigned int order) |
| { |
| u8 tag; |
| unsigned long i; |
| |
| if (unlikely(PageHighMem(page))) |
| return; |
| |
| tag = random_tag(); |
| for (i = 0; i < (1 << order); i++) |
| page_kasan_tag_set(page + i, tag); |
| kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order); |
| } |
| |
| void kasan_free_pages(struct page *page, unsigned int order) |
| { |
| if (likely(!PageHighMem(page))) |
| kasan_poison_shadow(page_address(page), |
| PAGE_SIZE << order, |
| KASAN_FREE_PAGE); |
| } |
| |
| /* |
| * Adaptive redzone policy taken from the userspace AddressSanitizer runtime. |
| * For larger allocations larger redzones are used. |
| */ |
| static inline unsigned int optimal_redzone(unsigned int object_size) |
| { |
| if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) |
| return 0; |
| |
| return |
| 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; |
| } |
| |
| void kasan_cache_create(struct kmem_cache *cache, unsigned int *size, |
| slab_flags_t *flags) |
| { |
| unsigned int orig_size = *size; |
| unsigned int redzone_size; |
| int redzone_adjust; |
| |
| /* Add alloc meta. */ |
| cache->kasan_info.alloc_meta_offset = *size; |
| *size += sizeof(struct kasan_alloc_meta); |
| |
| /* Add free meta. */ |
| if (IS_ENABLED(CONFIG_KASAN_GENERIC) && |
| (cache->flags & SLAB_TYPESAFE_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_size = optimal_redzone(cache->object_size); |
| redzone_adjust = redzone_size - (*size - cache->object_size); |
| if (redzone_adjust > 0) |
| *size += redzone_adjust; |
| |
| *size = min_t(unsigned int, KMALLOC_MAX_SIZE, |
| max(*size, cache->object_size + redzone_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; |
| } |
| |
| 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); |
| } |
| |
| struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache, |
| const void *object) |
| { |
| 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; |
| } |
| |
| |
| static void kasan_set_free_info(struct kmem_cache *cache, |
| void *object, u8 tag) |
| { |
| struct kasan_alloc_meta *alloc_meta; |
| u8 idx = 0; |
| |
| alloc_meta = get_alloc_info(cache, object); |
| |
| #ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY |
| idx = alloc_meta->free_track_idx; |
| alloc_meta->free_pointer_tag[idx] = tag; |
| alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS; |
| #endif |
| |
| set_track(&alloc_meta->free_track[idx], GFP_NOWAIT); |
| } |
| |
| void kasan_poison_slab(struct page *page) |
| { |
| unsigned long i; |
| |
| for (i = 0; i < compound_nr(page); i++) |
| page_kasan_tag_reset(page + i); |
| kasan_poison_shadow(page_address(page), page_size(page), |
| KASAN_KMALLOC_REDZONE); |
| } |
| |
| void kasan_unpoison_object_data(struct kmem_cache *cache, void *object) |
| { |
| kasan_unpoison_shadow(object, cache->object_size); |
| } |
| |
| void kasan_poison_object_data(struct kmem_cache *cache, void *object) |
| { |
| kasan_poison_shadow(object, |
| round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE), |
| KASAN_KMALLOC_REDZONE); |
| } |
| |
| /* |
| * This function assigns a tag to an object considering the following: |
| * 1. A cache might have a constructor, which might save a pointer to a slab |
| * object somewhere (e.g. in the object itself). We preassign a tag for |
| * each object in caches with constructors during slab creation and reuse |
| * the same tag each time a particular object is allocated. |
| * 2. A cache might be SLAB_TYPESAFE_BY_RCU, which means objects can be |
| * accessed after being freed. We preassign tags for objects in these |
| * caches as well. |
| * 3. For SLAB allocator we can't preassign tags randomly since the freelist |
| * is stored as an array of indexes instead of a linked list. Assign tags |
| * based on objects indexes, so that objects that are next to each other |
| * get different tags. |
| */ |
| static u8 assign_tag(struct kmem_cache *cache, const void *object, |
| bool init, bool keep_tag) |
| { |
| /* |
| * 1. When an object is kmalloc()'ed, two hooks are called: |
| * kasan_slab_alloc() and kasan_kmalloc(). We assign the |
| * tag only in the first one. |
| * 2. We reuse the same tag for krealloc'ed objects. |
| */ |
| if (keep_tag) |
| return get_tag(object); |
| |
| /* |
| * If the cache neither has a constructor nor has SLAB_TYPESAFE_BY_RCU |
| * set, assign a tag when the object is being allocated (init == false). |
| */ |
| if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU)) |
| return init ? KASAN_TAG_KERNEL : random_tag(); |
| |
| /* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU: */ |
| #ifdef CONFIG_SLAB |
| /* For SLAB assign tags based on the object index in the freelist. */ |
| return (u8)obj_to_index(cache, virt_to_page(object), (void *)object); |
| #else |
| /* |
| * For SLUB assign a random tag during slab creation, otherwise reuse |
| * the already assigned tag. |
| */ |
| return init ? random_tag() : get_tag(object); |
| #endif |
| } |
| |
| void * __must_check kasan_init_slab_obj(struct kmem_cache *cache, |
| const void *object) |
| { |
| struct kasan_alloc_meta *alloc_info; |
| |
| if (!(cache->flags & SLAB_KASAN)) |
| return (void *)object; |
| |
| alloc_info = get_alloc_info(cache, object); |
| __memset(alloc_info, 0, sizeof(*alloc_info)); |
| |
| if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) |
| object = set_tag(object, |
| assign_tag(cache, object, true, false)); |
| |
| return (void *)object; |
| } |
| |
| static inline bool shadow_invalid(u8 tag, s8 shadow_byte) |
| { |
| if (IS_ENABLED(CONFIG_KASAN_GENERIC)) |
| return shadow_byte < 0 || |
| shadow_byte >= KASAN_SHADOW_SCALE_SIZE; |
| |
| /* else CONFIG_KASAN_SW_TAGS: */ |
| if ((u8)shadow_byte == KASAN_TAG_INVALID) |
| return true; |
| if ((tag != KASAN_TAG_KERNEL) && (tag != (u8)shadow_byte)) |
| return true; |
| |
| return false; |
| } |
| |
| static bool __kasan_slab_free(struct kmem_cache *cache, void *object, |
| unsigned long ip, bool quarantine) |
| { |
| s8 shadow_byte; |
| u8 tag; |
| void *tagged_object; |
| unsigned long rounded_up_size; |
| |
| tag = get_tag(object); |
| tagged_object = object; |
| object = reset_tag(object); |
| |
| if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) != |
| object)) { |
| kasan_report_invalid_free(tagged_object, ip); |
| return true; |
| } |
| |
| /* RCU slabs could be legally used after free within the RCU period */ |
| if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU)) |
| return false; |
| |
| shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object)); |
| if (shadow_invalid(tag, shadow_byte)) { |
| kasan_report_invalid_free(tagged_object, ip); |
| return true; |
| } |
| |
| rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE); |
| kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE); |
| |
| if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) || |
| unlikely(!(cache->flags & SLAB_KASAN))) |
| return false; |
| |
| kasan_set_free_info(cache, object, tag); |
| |
| quarantine_put(get_free_info(cache, object), cache); |
| |
| return IS_ENABLED(CONFIG_KASAN_GENERIC); |
| } |
| |
| bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip) |
| { |
| return __kasan_slab_free(cache, object, ip, true); |
| } |
| |
| static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, |
| size_t size, gfp_t flags, bool keep_tag) |
| { |
| unsigned long redzone_start; |
| unsigned long redzone_end; |
| u8 tag = 0xff; |
| |
| if (gfpflags_allow_blocking(flags)) |
| quarantine_reduce(); |
| |
| if (unlikely(object == NULL)) |
| return NULL; |
| |
| redzone_start = round_up((unsigned long)(object + size), |
| KASAN_SHADOW_SCALE_SIZE); |
| redzone_end = round_up((unsigned long)object + cache->object_size, |
| KASAN_SHADOW_SCALE_SIZE); |
| |
| if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) |
| tag = assign_tag(cache, object, false, keep_tag); |
| |
| /* Tag is ignored in set_tag without CONFIG_KASAN_SW_TAGS */ |
| kasan_unpoison_shadow(set_tag(object, tag), 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); |
| |
| return set_tag(object, tag); |
| } |
| |
| void * __must_check kasan_slab_alloc(struct kmem_cache *cache, void *object, |
| gfp_t flags) |
| { |
| return __kasan_kmalloc(cache, object, cache->object_size, flags, false); |
| } |
| |
| void * __must_check kasan_kmalloc(struct kmem_cache *cache, const void *object, |
| size_t size, gfp_t flags) |
| { |
| return __kasan_kmalloc(cache, object, size, flags, true); |
| } |
| EXPORT_SYMBOL(kasan_kmalloc); |
| |
| void * __must_check 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 NULL; |
| |
| page = virt_to_page(ptr); |
| redzone_start = round_up((unsigned long)(ptr + size), |
| KASAN_SHADOW_SCALE_SIZE); |
| redzone_end = (unsigned long)ptr + page_size(page); |
| |
| kasan_unpoison_shadow(ptr, size); |
| kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, |
| KASAN_PAGE_REDZONE); |
| |
| return (void *)ptr; |
| } |
| |
| void * __must_check kasan_krealloc(const void *object, size_t size, gfp_t flags) |
| { |
| struct page *page; |
| |
| if (unlikely(object == ZERO_SIZE_PTR)) |
| return (void *)object; |
| |
| page = virt_to_head_page(object); |
| |
| if (unlikely(!PageSlab(page))) |
| return kasan_kmalloc_large(object, size, flags); |
| else |
| return __kasan_kmalloc(page->slab_cache, object, size, |
| flags, true); |
| } |
| |
| void kasan_poison_kfree(void *ptr, unsigned long ip) |
| { |
| struct page *page; |
| |
| page = virt_to_head_page(ptr); |
| |
| if (unlikely(!PageSlab(page))) { |
| if (ptr != page_address(page)) { |
| kasan_report_invalid_free(ptr, ip); |
| return; |
| } |
| kasan_poison_shadow(ptr, page_size(page), KASAN_FREE_PAGE); |
| } else { |
| __kasan_slab_free(page->slab_cache, ptr, ip, false); |
| } |
| } |
| |
| void kasan_kfree_large(void *ptr, unsigned long ip) |
| { |
| if (ptr != page_address(virt_to_head_page(ptr))) |
| kasan_report_invalid_free(ptr, ip); |
| /* The object will be poisoned by page_alloc. */ |
| } |
| |
| #ifndef CONFIG_KASAN_VMALLOC |
| int kasan_module_alloc(void *addr, size_t size) |
| { |
| void *ret; |
| size_t scaled_size; |
| size_t shadow_size; |
| unsigned long shadow_start; |
| |
| shadow_start = (unsigned long)kasan_mem_to_shadow(addr); |
| scaled_size = (size + KASAN_SHADOW_MASK) >> KASAN_SHADOW_SCALE_SHIFT; |
| shadow_size = round_up(scaled_size, PAGE_SIZE); |
| |
| if (WARN_ON(!PAGE_ALIGNED(shadow_start))) |
| return -EINVAL; |
| |
| ret = __vmalloc_node_range(shadow_size, 1, shadow_start, |
| shadow_start + shadow_size, |
| GFP_KERNEL, |
| PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE, |
| __builtin_return_address(0)); |
| |
| if (ret) { |
| __memset(ret, KASAN_SHADOW_INIT, shadow_size); |
| find_vm_area(addr)->flags |= VM_KASAN; |
| kmemleak_ignore(ret); |
| return 0; |
| } |
| |
| return -ENOMEM; |
| } |
| |
| void kasan_free_shadow(const struct vm_struct *vm) |
| { |
| if (vm->flags & VM_KASAN) |
| vfree(kasan_mem_to_shadow(vm->addr)); |
| } |
| #endif |
| |
| extern void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip); |
| extern bool report_enabled(void); |
| |
| bool kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip) |
| { |
| unsigned long flags = user_access_save(); |
| bool ret = false; |
| |
| if (likely(report_enabled())) { |
| __kasan_report(addr, size, is_write, ip); |
| ret = true; |
| } |
| |
| user_access_restore(flags); |
| |
| return ret; |
| } |
| |
| #ifdef CONFIG_MEMORY_HOTPLUG |
| static bool shadow_mapped(unsigned long addr) |
| { |
| pgd_t *pgd = pgd_offset_k(addr); |
| p4d_t *p4d; |
| pud_t *pud; |
| pmd_t *pmd; |
| pte_t *pte; |
| |
| if (pgd_none(*pgd)) |
| return false; |
| p4d = p4d_offset(pgd, addr); |
| if (p4d_none(*p4d)) |
| return false; |
| pud = pud_offset(p4d, addr); |
| if (pud_none(*pud)) |
| return false; |
| |
| /* |
| * We can't use pud_large() or pud_huge(), the first one is |
| * arch-specific, the last one depends on HUGETLB_PAGE. So let's abuse |
| * pud_bad(), if pud is bad then it's bad because it's huge. |
| */ |
| if (pud_bad(*pud)) |
| return true; |
| pmd = pmd_offset(pud, addr); |
| if (pmd_none(*pmd)) |
| return false; |
| |
| if (pmd_bad(*pmd)) |
| return true; |
| pte = pte_offset_kernel(pmd, addr); |
| return !pte_none(*pte); |
| } |
| |
| static int __meminit kasan_mem_notifier(struct notifier_block *nb, |
| unsigned long action, void *data) |
| { |
| struct memory_notify *mem_data = data; |
| unsigned long nr_shadow_pages, start_kaddr, shadow_start; |
| unsigned long shadow_end, shadow_size; |
| |
| nr_shadow_pages = mem_data->nr_pages >> KASAN_SHADOW_SCALE_SHIFT; |
| start_kaddr = (unsigned long)pfn_to_kaddr(mem_data->start_pfn); |
| shadow_start = (unsigned long)kasan_mem_to_shadow((void *)start_kaddr); |
| shadow_size = nr_shadow_pages << PAGE_SHIFT; |
| shadow_end = shadow_start + shadow_size; |
| |
| if (WARN_ON(mem_data->nr_pages % KASAN_SHADOW_SCALE_SIZE) || |
| WARN_ON(start_kaddr % (KASAN_SHADOW_SCALE_SIZE << PAGE_SHIFT))) |
| return NOTIFY_BAD; |
| |
| switch (action) { |
| case MEM_GOING_ONLINE: { |
| void *ret; |
| |
| /* |
| * If shadow is mapped already than it must have been mapped |
| * during the boot. This could happen if we onlining previously |
| * offlined memory. |
| */ |
| if (shadow_mapped(shadow_start)) |
| return NOTIFY_OK; |
| |
| ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start, |
| shadow_end, GFP_KERNEL, |
| PAGE_KERNEL, VM_NO_GUARD, |
| pfn_to_nid(mem_data->start_pfn), |
| __builtin_return_address(0)); |
| if (!ret) |
| return NOTIFY_BAD; |
| |
| kmemleak_ignore(ret); |
| return NOTIFY_OK; |
| } |
| case MEM_CANCEL_ONLINE: |
| case MEM_OFFLINE: { |
| struct vm_struct *vm; |
| |
| /* |
| * shadow_start was either mapped during boot by kasan_init() |
| * or during memory online by __vmalloc_node_range(). |
| * In the latter case we can use vfree() to free shadow. |
| * Non-NULL result of the find_vm_area() will tell us if |
| * that was the second case. |
| * |
| * Currently it's not possible to free shadow mapped |
| * during boot by kasan_init(). It's because the code |
| * to do that hasn't been written yet. So we'll just |
| * leak the memory. |
| */ |
| vm = find_vm_area((void *)shadow_start); |
| if (vm) |
| vfree((void *)shadow_start); |
| } |
| } |
| |
| return NOTIFY_OK; |
| } |
| |
| static int __init kasan_memhotplug_init(void) |
| { |
| hotplug_memory_notifier(kasan_mem_notifier, 0); |
| |
| return 0; |
| } |
| |
| core_initcall(kasan_memhotplug_init); |
| #endif |
| |
| #ifdef CONFIG_KASAN_VMALLOC |
| static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, |
| void *unused) |
| { |
| unsigned long page; |
| pte_t pte; |
| |
| if (likely(!pte_none(*ptep))) |
| return 0; |
| |
| page = __get_free_page(GFP_KERNEL); |
| if (!page) |
| return -ENOMEM; |
| |
| memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE); |
| pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL); |
| |
| spin_lock(&init_mm.page_table_lock); |
| if (likely(pte_none(*ptep))) { |
| set_pte_at(&init_mm, addr, ptep, pte); |
| page = 0; |
| } |
| spin_unlock(&init_mm.page_table_lock); |
| if (page) |
| free_page(page); |
| return 0; |
| } |
| |
| int kasan_populate_vmalloc(unsigned long addr, unsigned long size) |
| { |
| unsigned long shadow_start, shadow_end; |
| int ret; |
| |
| if (!is_vmalloc_or_module_addr((void *)addr)) |
| return 0; |
| |
| shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr); |
| shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE); |
| shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size); |
| shadow_end = ALIGN(shadow_end, PAGE_SIZE); |
| |
| ret = apply_to_page_range(&init_mm, shadow_start, |
| shadow_end - shadow_start, |
| kasan_populate_vmalloc_pte, NULL); |
| if (ret) |
| return ret; |
| |
| flush_cache_vmap(shadow_start, shadow_end); |
| |
| /* |
| * We need to be careful about inter-cpu effects here. Consider: |
| * |
| * CPU#0 CPU#1 |
| * WRITE_ONCE(p, vmalloc(100)); while (x = READ_ONCE(p)) ; |
| * p[99] = 1; |
| * |
| * With compiler instrumentation, that ends up looking like this: |
| * |
| * CPU#0 CPU#1 |
| * // vmalloc() allocates memory |
| * // let a = area->addr |
| * // we reach kasan_populate_vmalloc |
| * // and call kasan_unpoison_shadow: |
| * STORE shadow(a), unpoison_val |
| * ... |
| * STORE shadow(a+99), unpoison_val x = LOAD p |
| * // rest of vmalloc process <data dependency> |
| * STORE p, a LOAD shadow(x+99) |
| * |
| * If there is no barrier between the end of unpoisioning the shadow |
| * and the store of the result to p, the stores could be committed |
| * in a different order by CPU#0, and CPU#1 could erroneously observe |
| * poison in the shadow. |
| * |
| * We need some sort of barrier between the stores. |
| * |
| * In the vmalloc() case, this is provided by a smp_wmb() in |
| * clear_vm_uninitialized_flag(). In the per-cpu allocator and in |
| * get_vm_area() and friends, the caller gets shadow allocated but |
| * doesn't have any pages mapped into the virtual address space that |
| * has been reserved. Mapping those pages in will involve taking and |
| * releasing a page-table lock, which will provide the barrier. |
| */ |
| |
| return 0; |
| } |
| |
| /* |
| * Poison the shadow for a vmalloc region. Called as part of the |
| * freeing process at the time the region is freed. |
| */ |
| void kasan_poison_vmalloc(const void *start, unsigned long size) |
| { |
| if (!is_vmalloc_or_module_addr(start)) |
| return; |
| |
| size = round_up(size, KASAN_SHADOW_SCALE_SIZE); |
| kasan_poison_shadow(start, size, KASAN_VMALLOC_INVALID); |
| } |
| |
| void kasan_unpoison_vmalloc(const void *start, unsigned long size) |
| { |
| if (!is_vmalloc_or_module_addr(start)) |
| return; |
| |
| kasan_unpoison_shadow(start, size); |
| } |
| |
| static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr, |
| void *unused) |
| { |
| unsigned long page; |
| |
| page = (unsigned long)__va(pte_pfn(*ptep) << PAGE_SHIFT); |
| |
| spin_lock(&init_mm.page_table_lock); |
| |
| if (likely(!pte_none(*ptep))) { |
| pte_clear(&init_mm, addr, ptep); |
| free_page(page); |
| } |
| spin_unlock(&init_mm.page_table_lock); |
| |
| return 0; |
| } |
| |
| /* |
| * Release the backing for the vmalloc region [start, end), which |
| * lies within the free region [free_region_start, free_region_end). |
| * |
| * This can be run lazily, long after the region was freed. It runs |
| * under vmap_area_lock, so it's not safe to interact with the vmalloc/vmap |
| * infrastructure. |
| * |
| * How does this work? |
| * ------------------- |
| * |
| * We have a region that is page aligned, labelled as A. |
| * That might not map onto the shadow in a way that is page-aligned: |
| * |
| * start end |
| * v v |
| * |????????|????????|AAAAAAAA|AA....AA|AAAAAAAA|????????| < vmalloc |
| * -------- -------- -------- -------- -------- |
| * | | | | | |
| * | | | /-------/ | |
| * \-------\|/------/ |/---------------/ |
| * ||| || |
| * |??AAAAAA|AAAAAAAA|AA??????| < shadow |
| * (1) (2) (3) |
| * |
| * First we align the start upwards and the end downwards, so that the |
| * shadow of the region aligns with shadow page boundaries. In the |
| * example, this gives us the shadow page (2). This is the shadow entirely |
| * covered by this allocation. |
| * |
| * Then we have the tricky bits. We want to know if we can free the |
| * partially covered shadow pages - (1) and (3) in the example. For this, |
| * we are given the start and end of the free region that contains this |
| * allocation. Extending our previous example, we could have: |
| * |
| * free_region_start free_region_end |
| * | start end | |
| * v v v v |
| * |FFFFFFFF|FFFFFFFF|AAAAAAAA|AA....AA|AAAAAAAA|FFFFFFFF| < vmalloc |
| * -------- -------- -------- -------- -------- |
| * | | | | | |
| * | | | /-------/ | |
| * \-------\|/------/ |/---------------/ |
| * ||| || |
| * |FFAAAAAA|AAAAAAAA|AAF?????| < shadow |
| * (1) (2) (3) |
| * |
| * Once again, we align the start of the free region up, and the end of |
| * the free region down so that the shadow is page aligned. So we can free |
| * page (1) - we know no allocation currently uses anything in that page, |
| * because all of it is in the vmalloc free region. But we cannot free |
| * page (3), because we can't be sure that the rest of it is unused. |
| * |
| * We only consider pages that contain part of the original region for |
| * freeing: we don't try to free other pages from the free region or we'd |
| * end up trying to free huge chunks of virtual address space. |
| * |
| * Concurrency |
| * ----------- |
| * |
| * How do we know that we're not freeing a page that is simultaneously |
| * being used for a fresh allocation in kasan_populate_vmalloc(_pte)? |
| * |
| * We _can_ have kasan_release_vmalloc and kasan_populate_vmalloc running |
| * at the same time. While we run under free_vmap_area_lock, the population |
| * code does not. |
| * |
| * free_vmap_area_lock instead operates to ensure that the larger range |
| * [free_region_start, free_region_end) is safe: because __alloc_vmap_area and |
| * the per-cpu region-finding algorithm both run under free_vmap_area_lock, |
| * no space identified as free will become used while we are running. This |
| * means that so long as we are careful with alignment and only free shadow |
| * pages entirely covered by the free region, we will not run in to any |
| * trouble - any simultaneous allocations will be for disjoint regions. |
| */ |
| void kasan_release_vmalloc(unsigned long start, unsigned long end, |
| unsigned long free_region_start, |
| unsigned long free_region_end) |
| { |
| void *shadow_start, *shadow_end; |
| unsigned long region_start, region_end; |
| unsigned long size; |
| |
| region_start = ALIGN(start, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE); |
| region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE); |
| |
| free_region_start = ALIGN(free_region_start, |
| PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE); |
| |
| if (start != region_start && |
| free_region_start < region_start) |
| region_start -= PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE; |
| |
| free_region_end = ALIGN_DOWN(free_region_end, |
| PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE); |
| |
| if (end != region_end && |
| free_region_end > region_end) |
| region_end += PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE; |
| |
| shadow_start = kasan_mem_to_shadow((void *)region_start); |
| shadow_end = kasan_mem_to_shadow((void *)region_end); |
| |
| if (shadow_end > shadow_start) { |
| size = shadow_end - shadow_start; |
| apply_to_existing_page_range(&init_mm, |
| (unsigned long)shadow_start, |
| size, kasan_depopulate_vmalloc_pte, |
| NULL); |
| flush_tlb_kernel_range((unsigned long)shadow_start, |
| (unsigned long)shadow_end); |
| } |
| } |
| #endif |