kasan: fix null pointer dereference in kasan_record_aux_stack
[linux-2.6-microblaze.git] / mm / kasan / generic.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * This file contains core generic KASAN code.
4  *
5  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
6  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7  *
8  * Some code borrowed from https://github.com/xairy/kasan-prototype by
9  *        Andrey Konovalov <andreyknvl@gmail.com>
10  */
11
12 #include <linux/export.h>
13 #include <linux/interrupt.h>
14 #include <linux/init.h>
15 #include <linux/kasan.h>
16 #include <linux/kernel.h>
17 #include <linux/kmemleak.h>
18 #include <linux/linkage.h>
19 #include <linux/memblock.h>
20 #include <linux/memory.h>
21 #include <linux/mm.h>
22 #include <linux/module.h>
23 #include <linux/printk.h>
24 #include <linux/sched.h>
25 #include <linux/sched/task_stack.h>
26 #include <linux/slab.h>
27 #include <linux/stacktrace.h>
28 #include <linux/string.h>
29 #include <linux/types.h>
30 #include <linux/vmalloc.h>
31 #include <linux/bug.h>
32
33 #include "kasan.h"
34 #include "../slab.h"
35
36 /*
37  * All functions below always inlined so compiler could
38  * perform better optimizations in each of __asan_loadX/__assn_storeX
39  * depending on memory access size X.
40  */
41
42 static __always_inline bool memory_is_poisoned_1(unsigned long addr)
43 {
44         s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
45
46         if (unlikely(shadow_value)) {
47                 s8 last_accessible_byte = addr & KASAN_GRANULE_MASK;
48                 return unlikely(last_accessible_byte >= shadow_value);
49         }
50
51         return false;
52 }
53
54 static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
55                                                 unsigned long size)
56 {
57         u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
58
59         /*
60          * Access crosses 8(shadow size)-byte boundary. Such access maps
61          * into 2 shadow bytes, so we need to check them both.
62          */
63         if (unlikely(((addr + size - 1) & KASAN_GRANULE_MASK) < size - 1))
64                 return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
65
66         return memory_is_poisoned_1(addr + size - 1);
67 }
68
69 static __always_inline bool memory_is_poisoned_16(unsigned long addr)
70 {
71         u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
72
73         /* Unaligned 16-bytes access maps into 3 shadow bytes. */
74         if (unlikely(!IS_ALIGNED(addr, KASAN_GRANULE_SIZE)))
75                 return *shadow_addr || memory_is_poisoned_1(addr + 15);
76
77         return *shadow_addr;
78 }
79
80 static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
81                                         size_t size)
82 {
83         while (size) {
84                 if (unlikely(*start))
85                         return (unsigned long)start;
86                 start++;
87                 size--;
88         }
89
90         return 0;
91 }
92
93 static __always_inline unsigned long memory_is_nonzero(const void *start,
94                                                 const void *end)
95 {
96         unsigned int words;
97         unsigned long ret;
98         unsigned int prefix = (unsigned long)start % 8;
99
100         if (end - start <= 16)
101                 return bytes_is_nonzero(start, end - start);
102
103         if (prefix) {
104                 prefix = 8 - prefix;
105                 ret = bytes_is_nonzero(start, prefix);
106                 if (unlikely(ret))
107                         return ret;
108                 start += prefix;
109         }
110
111         words = (end - start) / 8;
112         while (words) {
113                 if (unlikely(*(u64 *)start))
114                         return bytes_is_nonzero(start, 8);
115                 start += 8;
116                 words--;
117         }
118
119         return bytes_is_nonzero(start, (end - start) % 8);
120 }
121
122 static __always_inline bool memory_is_poisoned_n(unsigned long addr,
123                                                 size_t size)
124 {
125         unsigned long ret;
126
127         ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
128                         kasan_mem_to_shadow((void *)addr + size - 1) + 1);
129
130         if (unlikely(ret)) {
131                 unsigned long last_byte = addr + size - 1;
132                 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
133
134                 if (unlikely(ret != (unsigned long)last_shadow ||
135                         ((long)(last_byte & KASAN_GRANULE_MASK) >= *last_shadow)))
136                         return true;
137         }
138         return false;
139 }
140
141 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
142 {
143         if (__builtin_constant_p(size)) {
144                 switch (size) {
145                 case 1:
146                         return memory_is_poisoned_1(addr);
147                 case 2:
148                 case 4:
149                 case 8:
150                         return memory_is_poisoned_2_4_8(addr, size);
151                 case 16:
152                         return memory_is_poisoned_16(addr);
153                 default:
154                         BUILD_BUG();
155                 }
156         }
157
158         return memory_is_poisoned_n(addr, size);
159 }
160
161 static __always_inline bool check_memory_region_inline(unsigned long addr,
162                                                 size_t size, bool write,
163                                                 unsigned long ret_ip)
164 {
165         if (unlikely(size == 0))
166                 return true;
167
168         if (unlikely(addr + size < addr))
169                 return !kasan_report(addr, size, write, ret_ip);
170
171         if (unlikely((void *)addr <
172                 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
173                 return !kasan_report(addr, size, write, ret_ip);
174         }
175
176         if (likely(!memory_is_poisoned(addr, size)))
177                 return true;
178
179         return !kasan_report(addr, size, write, ret_ip);
180 }
181
182 bool check_memory_region(unsigned long addr, size_t size, bool write,
183                                 unsigned long ret_ip)
184 {
185         return check_memory_region_inline(addr, size, write, ret_ip);
186 }
187
188 bool check_invalid_free(void *addr)
189 {
190         s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
191
192         return shadow_byte < 0 || shadow_byte >= KASAN_GRANULE_SIZE;
193 }
194
195 void kasan_cache_shrink(struct kmem_cache *cache)
196 {
197         quarantine_remove_cache(cache);
198 }
199
200 void kasan_cache_shutdown(struct kmem_cache *cache)
201 {
202         if (!__kmem_cache_empty(cache))
203                 quarantine_remove_cache(cache);
204 }
205
206 static void register_global(struct kasan_global *global)
207 {
208         size_t aligned_size = round_up(global->size, KASAN_GRANULE_SIZE);
209
210         unpoison_range(global->beg, global->size);
211
212         poison_range(global->beg + aligned_size,
213                      global->size_with_redzone - aligned_size,
214                      KASAN_GLOBAL_REDZONE);
215 }
216
217 void __asan_register_globals(struct kasan_global *globals, size_t size)
218 {
219         int i;
220
221         for (i = 0; i < size; i++)
222                 register_global(&globals[i]);
223 }
224 EXPORT_SYMBOL(__asan_register_globals);
225
226 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
227 {
228 }
229 EXPORT_SYMBOL(__asan_unregister_globals);
230
231 #define DEFINE_ASAN_LOAD_STORE(size)                                    \
232         void __asan_load##size(unsigned long addr)                      \
233         {                                                               \
234                 check_memory_region_inline(addr, size, false, _RET_IP_);\
235         }                                                               \
236         EXPORT_SYMBOL(__asan_load##size);                               \
237         __alias(__asan_load##size)                                      \
238         void __asan_load##size##_noabort(unsigned long);                \
239         EXPORT_SYMBOL(__asan_load##size##_noabort);                     \
240         void __asan_store##size(unsigned long addr)                     \
241         {                                                               \
242                 check_memory_region_inline(addr, size, true, _RET_IP_); \
243         }                                                               \
244         EXPORT_SYMBOL(__asan_store##size);                              \
245         __alias(__asan_store##size)                                     \
246         void __asan_store##size##_noabort(unsigned long);               \
247         EXPORT_SYMBOL(__asan_store##size##_noabort)
248
249 DEFINE_ASAN_LOAD_STORE(1);
250 DEFINE_ASAN_LOAD_STORE(2);
251 DEFINE_ASAN_LOAD_STORE(4);
252 DEFINE_ASAN_LOAD_STORE(8);
253 DEFINE_ASAN_LOAD_STORE(16);
254
255 void __asan_loadN(unsigned long addr, size_t size)
256 {
257         check_memory_region(addr, size, false, _RET_IP_);
258 }
259 EXPORT_SYMBOL(__asan_loadN);
260
261 __alias(__asan_loadN)
262 void __asan_loadN_noabort(unsigned long, size_t);
263 EXPORT_SYMBOL(__asan_loadN_noabort);
264
265 void __asan_storeN(unsigned long addr, size_t size)
266 {
267         check_memory_region(addr, size, true, _RET_IP_);
268 }
269 EXPORT_SYMBOL(__asan_storeN);
270
271 __alias(__asan_storeN)
272 void __asan_storeN_noabort(unsigned long, size_t);
273 EXPORT_SYMBOL(__asan_storeN_noabort);
274
275 /* to shut up compiler complaints */
276 void __asan_handle_no_return(void) {}
277 EXPORT_SYMBOL(__asan_handle_no_return);
278
279 /* Emitted by compiler to poison alloca()ed objects. */
280 void __asan_alloca_poison(unsigned long addr, size_t size)
281 {
282         size_t rounded_up_size = round_up(size, KASAN_GRANULE_SIZE);
283         size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
284                         rounded_up_size;
285         size_t rounded_down_size = round_down(size, KASAN_GRANULE_SIZE);
286
287         const void *left_redzone = (const void *)(addr -
288                         KASAN_ALLOCA_REDZONE_SIZE);
289         const void *right_redzone = (const void *)(addr + rounded_up_size);
290
291         WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
292
293         unpoison_range((const void *)(addr + rounded_down_size),
294                        size - rounded_down_size);
295         poison_range(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
296                      KASAN_ALLOCA_LEFT);
297         poison_range(right_redzone, padding_size + KASAN_ALLOCA_REDZONE_SIZE,
298                      KASAN_ALLOCA_RIGHT);
299 }
300 EXPORT_SYMBOL(__asan_alloca_poison);
301
302 /* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
303 void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
304 {
305         if (unlikely(!stack_top || stack_top > stack_bottom))
306                 return;
307
308         unpoison_range(stack_top, stack_bottom - stack_top);
309 }
310 EXPORT_SYMBOL(__asan_allocas_unpoison);
311
312 /* Emitted by the compiler to [un]poison local variables. */
313 #define DEFINE_ASAN_SET_SHADOW(byte) \
314         void __asan_set_shadow_##byte(const void *addr, size_t size)    \
315         {                                                               \
316                 __memset((void *)addr, 0x##byte, size);                 \
317         }                                                               \
318         EXPORT_SYMBOL(__asan_set_shadow_##byte)
319
320 DEFINE_ASAN_SET_SHADOW(00);
321 DEFINE_ASAN_SET_SHADOW(f1);
322 DEFINE_ASAN_SET_SHADOW(f2);
323 DEFINE_ASAN_SET_SHADOW(f3);
324 DEFINE_ASAN_SET_SHADOW(f5);
325 DEFINE_ASAN_SET_SHADOW(f8);
326
327 void kasan_record_aux_stack(void *addr)
328 {
329         struct page *page = kasan_addr_to_page(addr);
330         struct kmem_cache *cache;
331         struct kasan_alloc_meta *alloc_meta;
332         void *object;
333
334         if (!(page && PageSlab(page)))
335                 return;
336
337         cache = page->slab_cache;
338         object = nearest_obj(cache, page, addr);
339         alloc_meta = kasan_get_alloc_meta(cache, object);
340         if (!alloc_meta)
341                 return;
342
343         alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
344         alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
345 }
346
347 void kasan_set_free_info(struct kmem_cache *cache,
348                                 void *object, u8 tag)
349 {
350         struct kasan_free_meta *free_meta;
351
352         free_meta = kasan_get_free_meta(cache, object);
353         if (!free_meta)
354                 return;
355
356         kasan_set_track(&free_meta->free_track, GFP_NOWAIT);
357         /* The object was freed and has free track set. */
358         *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREETRACK;
359 }
360
361 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
362                                 void *object, u8 tag)
363 {
364         if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_KMALLOC_FREETRACK)
365                 return NULL;
366         /* Free meta must be present with KASAN_KMALLOC_FREETRACK. */
367         return &kasan_get_free_meta(cache, object)->free_track;
368 }