2 * This file contains shadow memory manipulation code.
4 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
5 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 * Some code borrowed from https://github.com/xairy/kasan-prototype by
8 * Andrey Konovalov <adech.fo@gmail.com>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17 #define DISABLE_BRANCH_PROFILING
19 #include <linux/export.h>
20 #include <linux/init.h>
21 #include <linux/kernel.h>
22 #include <linux/memblock.h>
23 #include <linux/memory.h>
25 #include <linux/module.h>
26 #include <linux/printk.h>
27 #include <linux/sched.h>
28 #include <linux/slab.h>
29 #include <linux/stacktrace.h>
30 #include <linux/string.h>
31 #include <linux/types.h>
32 #include <linux/vmalloc.h>
33 #include <linux/kasan.h>
39 * Poisons the shadow memory for 'size' bytes starting from 'addr'.
40 * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
42 static void kasan_poison_shadow(const void *address
, size_t size
, u8 value
)
44 void *shadow_start
, *shadow_end
;
46 shadow_start
= kasan_mem_to_shadow(address
);
47 shadow_end
= kasan_mem_to_shadow(address
+ size
);
49 memset(shadow_start
, value
, shadow_end
- shadow_start
);
52 void kasan_unpoison_shadow(const void *address
, size_t size
)
54 kasan_poison_shadow(address
, size
, 0);
56 if (size
& KASAN_SHADOW_MASK
) {
57 u8
*shadow
= (u8
*)kasan_mem_to_shadow(address
+ size
);
58 *shadow
= size
& KASAN_SHADOW_MASK
;
64 * All functions below always inlined so compiler could
65 * perform better optimizations in each of __asan_loadX/__assn_storeX
66 * depending on memory access size X.
69 static __always_inline
bool memory_is_poisoned_1(unsigned long addr
)
71 s8 shadow_value
= *(s8
*)kasan_mem_to_shadow((void *)addr
);
73 if (unlikely(shadow_value
)) {
74 s8 last_accessible_byte
= addr
& KASAN_SHADOW_MASK
;
75 return unlikely(last_accessible_byte
>= shadow_value
);
81 static __always_inline
bool memory_is_poisoned_2(unsigned long addr
)
83 u16
*shadow_addr
= (u16
*)kasan_mem_to_shadow((void *)addr
);
85 if (unlikely(*shadow_addr
)) {
86 if (memory_is_poisoned_1(addr
+ 1))
90 * If single shadow byte covers 2-byte access, we don't
91 * need to do anything more. Otherwise, test the first
94 if (likely(((addr
+ 1) & KASAN_SHADOW_MASK
) != 0))
97 return unlikely(*(u8
*)shadow_addr
);
103 static __always_inline
bool memory_is_poisoned_4(unsigned long addr
)
105 u16
*shadow_addr
= (u16
*)kasan_mem_to_shadow((void *)addr
);
107 if (unlikely(*shadow_addr
)) {
108 if (memory_is_poisoned_1(addr
+ 3))
112 * If single shadow byte covers 4-byte access, we don't
113 * need to do anything more. Otherwise, test the first
116 if (likely(((addr
+ 3) & KASAN_SHADOW_MASK
) >= 3))
119 return unlikely(*(u8
*)shadow_addr
);
125 static __always_inline
bool memory_is_poisoned_8(unsigned long addr
)
127 u16
*shadow_addr
= (u16
*)kasan_mem_to_shadow((void *)addr
);
129 if (unlikely(*shadow_addr
)) {
130 if (memory_is_poisoned_1(addr
+ 7))
134 * If single shadow byte covers 8-byte access, we don't
135 * need to do anything more. Otherwise, test the first
138 if (likely(IS_ALIGNED(addr
, KASAN_SHADOW_SCALE_SIZE
)))
141 return unlikely(*(u8
*)shadow_addr
);
147 static __always_inline
bool memory_is_poisoned_16(unsigned long addr
)
149 u32
*shadow_addr
= (u32
*)kasan_mem_to_shadow((void *)addr
);
151 if (unlikely(*shadow_addr
)) {
152 u16 shadow_first_bytes
= *(u16
*)shadow_addr
;
154 if (unlikely(shadow_first_bytes
))
158 * If two shadow bytes covers 16-byte access, we don't
159 * need to do anything more. Otherwise, test the last
162 if (likely(IS_ALIGNED(addr
, KASAN_SHADOW_SCALE_SIZE
)))
165 return memory_is_poisoned_1(addr
+ 15);
171 static __always_inline
unsigned long bytes_is_zero(const u8
*start
,
175 if (unlikely(*start
))
176 return (unsigned long)start
;
184 static __always_inline
unsigned long memory_is_zero(const void *start
,
189 unsigned int prefix
= (unsigned long)start
% 8;
191 if (end
- start
<= 16)
192 return bytes_is_zero(start
, end
- start
);
196 ret
= bytes_is_zero(start
, prefix
);
202 words
= (end
- start
) / 8;
204 if (unlikely(*(u64
*)start
))
205 return bytes_is_zero(start
, 8);
210 return bytes_is_zero(start
, (end
- start
) % 8);
213 static __always_inline
bool memory_is_poisoned_n(unsigned long addr
,
218 ret
= memory_is_zero(kasan_mem_to_shadow((void *)addr
),
219 kasan_mem_to_shadow((void *)addr
+ size
- 1) + 1);
222 unsigned long last_byte
= addr
+ size
- 1;
223 s8
*last_shadow
= (s8
*)kasan_mem_to_shadow((void *)last_byte
);
225 if (unlikely(ret
!= (unsigned long)last_shadow
||
226 ((long)(last_byte
& KASAN_SHADOW_MASK
) >= *last_shadow
)))
232 static __always_inline
bool memory_is_poisoned(unsigned long addr
, size_t size
)
234 if (__builtin_constant_p(size
)) {
237 return memory_is_poisoned_1(addr
);
239 return memory_is_poisoned_2(addr
);
241 return memory_is_poisoned_4(addr
);
243 return memory_is_poisoned_8(addr
);
245 return memory_is_poisoned_16(addr
);
251 return memory_is_poisoned_n(addr
, size
);
255 static __always_inline
void check_memory_region(unsigned long addr
,
256 size_t size
, bool write
)
258 if (unlikely(size
== 0))
261 if (unlikely((void *)addr
<
262 kasan_shadow_to_mem((void *)KASAN_SHADOW_START
))) {
263 kasan_report(addr
, size
, write
, _RET_IP_
);
267 if (likely(!memory_is_poisoned(addr
, size
)))
270 kasan_report(addr
, size
, write
, _RET_IP_
);
273 void __asan_loadN(unsigned long addr
, size_t size
);
274 void __asan_storeN(unsigned long addr
, size_t size
);
277 void *memset(void *addr
, int c
, size_t len
)
279 __asan_storeN((unsigned long)addr
, len
);
281 return __memset(addr
, c
, len
);
285 void *memmove(void *dest
, const void *src
, size_t len
)
287 __asan_loadN((unsigned long)src
, len
);
288 __asan_storeN((unsigned long)dest
, len
);
290 return __memmove(dest
, src
, len
);
294 void *memcpy(void *dest
, const void *src
, size_t len
)
296 __asan_loadN((unsigned long)src
, len
);
297 __asan_storeN((unsigned long)dest
, len
);
299 return __memcpy(dest
, src
, len
);
302 void kasan_alloc_pages(struct page
*page
, unsigned int order
)
304 if (likely(!PageHighMem(page
)))
305 kasan_unpoison_shadow(page_address(page
), PAGE_SIZE
<< order
);
308 void kasan_free_pages(struct page
*page
, unsigned int order
)
310 if (likely(!PageHighMem(page
)))
311 kasan_poison_shadow(page_address(page
),
316 void kasan_poison_slab(struct page
*page
)
318 kasan_poison_shadow(page_address(page
),
319 PAGE_SIZE
<< compound_order(page
),
320 KASAN_KMALLOC_REDZONE
);
323 void kasan_unpoison_object_data(struct kmem_cache
*cache
, void *object
)
325 kasan_unpoison_shadow(object
, cache
->object_size
);
328 void kasan_poison_object_data(struct kmem_cache
*cache
, void *object
)
330 kasan_poison_shadow(object
,
331 round_up(cache
->object_size
, KASAN_SHADOW_SCALE_SIZE
),
332 KASAN_KMALLOC_REDZONE
);
335 void kasan_slab_alloc(struct kmem_cache
*cache
, void *object
)
337 kasan_kmalloc(cache
, object
, cache
->object_size
);
340 void kasan_slab_free(struct kmem_cache
*cache
, void *object
)
342 unsigned long size
= cache
->object_size
;
343 unsigned long rounded_up_size
= round_up(size
, KASAN_SHADOW_SCALE_SIZE
);
345 /* RCU slabs could be legally used after free within the RCU period */
346 if (unlikely(cache
->flags
& SLAB_DESTROY_BY_RCU
))
349 kasan_poison_shadow(object
, rounded_up_size
, KASAN_KMALLOC_FREE
);
352 void kasan_kmalloc(struct kmem_cache
*cache
, const void *object
, size_t size
)
354 unsigned long redzone_start
;
355 unsigned long redzone_end
;
357 if (unlikely(object
== NULL
))
360 redzone_start
= round_up((unsigned long)(object
+ size
),
361 KASAN_SHADOW_SCALE_SIZE
);
362 redzone_end
= round_up((unsigned long)object
+ cache
->object_size
,
363 KASAN_SHADOW_SCALE_SIZE
);
365 kasan_unpoison_shadow(object
, size
);
366 kasan_poison_shadow((void *)redzone_start
, redzone_end
- redzone_start
,
367 KASAN_KMALLOC_REDZONE
);
369 EXPORT_SYMBOL(kasan_kmalloc
);
371 void kasan_kmalloc_large(const void *ptr
, size_t size
)
374 unsigned long redzone_start
;
375 unsigned long redzone_end
;
377 if (unlikely(ptr
== NULL
))
380 page
= virt_to_page(ptr
);
381 redzone_start
= round_up((unsigned long)(ptr
+ size
),
382 KASAN_SHADOW_SCALE_SIZE
);
383 redzone_end
= (unsigned long)ptr
+ (PAGE_SIZE
<< compound_order(page
));
385 kasan_unpoison_shadow(ptr
, size
);
386 kasan_poison_shadow((void *)redzone_start
, redzone_end
- redzone_start
,
390 void kasan_krealloc(const void *object
, size_t size
)
394 if (unlikely(object
== ZERO_SIZE_PTR
))
397 page
= virt_to_head_page(object
);
399 if (unlikely(!PageSlab(page
)))
400 kasan_kmalloc_large(object
, size
);
402 kasan_kmalloc(page
->slab_cache
, object
, size
);
405 void kasan_kfree(void *ptr
)
409 page
= virt_to_head_page(ptr
);
411 if (unlikely(!PageSlab(page
)))
412 kasan_poison_shadow(ptr
, PAGE_SIZE
<< compound_order(page
),
415 kasan_slab_free(page
->slab_cache
, ptr
);
418 void kasan_kfree_large(const void *ptr
)
420 struct page
*page
= virt_to_page(ptr
);
422 kasan_poison_shadow(ptr
, PAGE_SIZE
<< compound_order(page
),
426 int kasan_module_alloc(void *addr
, size_t size
)
430 unsigned long shadow_start
;
432 shadow_start
= (unsigned long)kasan_mem_to_shadow(addr
);
433 shadow_size
= round_up(size
>> KASAN_SHADOW_SCALE_SHIFT
,
436 if (WARN_ON(!PAGE_ALIGNED(shadow_start
)))
439 ret
= __vmalloc_node_range(shadow_size
, 1, shadow_start
,
440 shadow_start
+ shadow_size
,
441 GFP_KERNEL
| __GFP_HIGHMEM
| __GFP_ZERO
,
442 PAGE_KERNEL
, VM_NO_GUARD
, NUMA_NO_NODE
,
443 __builtin_return_address(0));
446 find_vm_area(addr
)->flags
|= VM_KASAN
;
453 void kasan_free_shadow(const struct vm_struct
*vm
)
455 if (vm
->flags
& VM_KASAN
)
456 vfree(kasan_mem_to_shadow(vm
->addr
));
459 static void register_global(struct kasan_global
*global
)
461 size_t aligned_size
= round_up(global
->size
, KASAN_SHADOW_SCALE_SIZE
);
463 kasan_unpoison_shadow(global
->beg
, global
->size
);
465 kasan_poison_shadow(global
->beg
+ aligned_size
,
466 global
->size_with_redzone
- aligned_size
,
467 KASAN_GLOBAL_REDZONE
);
470 void __asan_register_globals(struct kasan_global
*globals
, size_t size
)
474 for (i
= 0; i
< size
; i
++)
475 register_global(&globals
[i
]);
477 EXPORT_SYMBOL(__asan_register_globals
);
479 void __asan_unregister_globals(struct kasan_global
*globals
, size_t size
)
482 EXPORT_SYMBOL(__asan_unregister_globals
);
484 #define DEFINE_ASAN_LOAD_STORE(size) \
485 void __asan_load##size(unsigned long addr) \
487 check_memory_region(addr, size, false); \
489 EXPORT_SYMBOL(__asan_load##size); \
490 __alias(__asan_load##size) \
491 void __asan_load##size##_noabort(unsigned long); \
492 EXPORT_SYMBOL(__asan_load##size##_noabort); \
493 void __asan_store##size(unsigned long addr) \
495 check_memory_region(addr, size, true); \
497 EXPORT_SYMBOL(__asan_store##size); \
498 __alias(__asan_store##size) \
499 void __asan_store##size##_noabort(unsigned long); \
500 EXPORT_SYMBOL(__asan_store##size##_noabort)
502 DEFINE_ASAN_LOAD_STORE(1);
503 DEFINE_ASAN_LOAD_STORE(2);
504 DEFINE_ASAN_LOAD_STORE(4);
505 DEFINE_ASAN_LOAD_STORE(8);
506 DEFINE_ASAN_LOAD_STORE(16);
508 void __asan_loadN(unsigned long addr
, size_t size
)
510 check_memory_region(addr
, size
, false);
512 EXPORT_SYMBOL(__asan_loadN
);
514 __alias(__asan_loadN
)
515 void __asan_loadN_noabort(unsigned long, size_t);
516 EXPORT_SYMBOL(__asan_loadN_noabort
);
518 void __asan_storeN(unsigned long addr
, size_t size
)
520 check_memory_region(addr
, size
, true);
522 EXPORT_SYMBOL(__asan_storeN
);
524 __alias(__asan_storeN
)
525 void __asan_storeN_noabort(unsigned long, size_t);
526 EXPORT_SYMBOL(__asan_storeN_noabort
);
528 /* to shut up compiler complaints */
529 void __asan_handle_no_return(void) {}
530 EXPORT_SYMBOL(__asan_handle_no_return
);
532 #ifdef CONFIG_MEMORY_HOTPLUG
533 static int kasan_mem_notifier(struct notifier_block
*nb
,
534 unsigned long action
, void *data
)
536 return (action
== MEM_GOING_ONLINE
) ? NOTIFY_BAD
: NOTIFY_OK
;
539 static int __init
kasan_memhotplug_init(void)
541 pr_err("WARNING: KASAN doesn't support memory hot-add\n");
542 pr_err("Memory hot-add will be disabled\n");
544 hotplug_memory_notifier(kasan_mem_notifier
, 0);
549 module_init(kasan_memhotplug_init
);