Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
new file mode 100644
index 0000000..6814d6d
--- /dev/null
+++ b/mm/kasan/common.c
@@ -0,0 +1,746 @@
+// 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/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>
+#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 "kasan.h"
+#include "../slab.h"
+
+static inline int in_irqentry_text(unsigned long ptr)
+{
+ 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);
+}
+
+static inline unsigned int filter_irq_stacks(unsigned long *entries,
+ unsigned int nr_entries)
+{
+ unsigned int i;
+
+ for (i = 0; i < nr_entries; i++) {
+ if (in_irqentry_text(entries[i])) {
+ /* Include the irqentry function into the stack. */
+ return i + 1;
+ }
+ }
+ return nr_entries;
+}
+
+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)
+{
+ check_memory_region((unsigned long)addr, len, true, _RET_IP_);
+
+ return __memset(addr, c, len);
+}
+
+#undef memmove
+void *memmove(void *dest, const void *src, size_t 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);
+}
+
+#undef memcpy
+void *memcpy(void *dest, const void *src, size_t 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);
+}
+
+/*
+ * 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. */
+}
+
+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));
+}
+
+extern void __kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip);
+
+void kasan_report(unsigned long addr, size_t size, bool is_write, unsigned long ip)
+{
+ unsigned long flags = user_access_save();
+ __kasan_report(addr, size, is_write, ip);
+ user_access_restore(flags);
+}
+
+#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