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16#include <linux/bitops.h>
17#include <linux/ftrace.h>
18#include <linux/init.h>
19#include <linux/kernel.h>
20#include <linux/mm.h>
21#include <linux/printk.h>
22#include <linux/sched.h>
23#include <linux/slab.h>
24#include <linux/stackdepot.h>
25#include <linux/stacktrace.h>
26#include <linux/string.h>
27#include <linux/types.h>
28#include <linux/kasan.h>
29#include <linux/module.h>
30
31#include <asm/sections.h>
32
33#include "kasan.h"
34#include "../slab.h"
35
36
37#define SHADOW_BYTES_PER_BLOCK 1
38#define SHADOW_BLOCKS_PER_ROW 16
39#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
40#define SHADOW_ROWS_AROUND_ADDR 2
41
42static const void *find_first_bad_addr(const void *addr, size_t size)
43{
44 u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
45 const void *first_bad_addr = addr;
46
47 while (!shadow_val && first_bad_addr < addr + size) {
48 first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
49 shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
50 }
51 return first_bad_addr;
52}
53
54static bool addr_has_shadow(struct kasan_access_info *info)
55{
56 return (info->access_addr >=
57 kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
58}
59
60static const char *get_shadow_bug_type(struct kasan_access_info *info)
61{
62 const char *bug_type = "unknown-crash";
63 u8 *shadow_addr;
64
65 info->first_bad_addr = find_first_bad_addr(info->access_addr,
66 info->access_size);
67
68 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
69
70
71
72
73
74 if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
75 shadow_addr++;
76
77 switch (*shadow_addr) {
78 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
79
80
81
82
83 bug_type = "out-of-bounds";
84 break;
85 case KASAN_PAGE_REDZONE:
86 case KASAN_KMALLOC_REDZONE:
87 bug_type = "slab-out-of-bounds";
88 break;
89 case KASAN_GLOBAL_REDZONE:
90 bug_type = "global-out-of-bounds";
91 break;
92 case KASAN_STACK_LEFT:
93 case KASAN_STACK_MID:
94 case KASAN_STACK_RIGHT:
95 case KASAN_STACK_PARTIAL:
96 bug_type = "stack-out-of-bounds";
97 break;
98 case KASAN_FREE_PAGE:
99 case KASAN_KMALLOC_FREE:
100 bug_type = "use-after-free";
101 break;
102 case KASAN_USE_AFTER_SCOPE:
103 bug_type = "use-after-scope";
104 break;
105 case KASAN_ALLOCA_LEFT:
106 case KASAN_ALLOCA_RIGHT:
107 bug_type = "alloca-out-of-bounds";
108 break;
109 }
110
111 return bug_type;
112}
113
114static const char *get_wild_bug_type(struct kasan_access_info *info)
115{
116 const char *bug_type = "unknown-crash";
117
118 if ((unsigned long)info->access_addr < PAGE_SIZE)
119 bug_type = "null-ptr-deref";
120 else if ((unsigned long)info->access_addr < TASK_SIZE)
121 bug_type = "user-memory-access";
122 else
123 bug_type = "wild-memory-access";
124
125 return bug_type;
126}
127
128static const char *get_bug_type(struct kasan_access_info *info)
129{
130 if (addr_has_shadow(info))
131 return get_shadow_bug_type(info);
132 return get_wild_bug_type(info);
133}
134
135static void print_error_description(struct kasan_access_info *info)
136{
137 const char *bug_type = get_bug_type(info);
138
139 pr_err("BUG: KASAN: %s in %pS\n",
140 bug_type, (void *)info->ip);
141 pr_err("%s of size %zu at addr %px by task %s/%d\n",
142 info->is_write ? "Write" : "Read", info->access_size,
143 info->access_addr, current->comm, task_pid_nr(current));
144}
145
146static inline bool kernel_or_module_addr(const void *addr)
147{
148 if (addr >= (void *)_stext && addr < (void *)_end)
149 return true;
150 if (is_module_address((unsigned long)addr))
151 return true;
152 return false;
153}
154
155static inline bool init_task_stack_addr(const void *addr)
156{
157 return addr >= (void *)&init_thread_union.stack &&
158 (addr <= (void *)&init_thread_union.stack +
159 sizeof(init_thread_union.stack));
160}
161
162static DEFINE_SPINLOCK(report_lock);
163
164static void kasan_start_report(unsigned long *flags)
165{
166
167
168
169 kasan_disable_current();
170 spin_lock_irqsave(&report_lock, *flags);
171 pr_err("==================================================================\n");
172}
173
174static void kasan_end_report(unsigned long *flags)
175{
176 pr_err("==================================================================\n");
177 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
178 spin_unlock_irqrestore(&report_lock, *flags);
179 if (panic_on_warn)
180 panic("panic_on_warn set ...\n");
181 kasan_enable_current();
182}
183
184static void print_track(struct kasan_track *track, const char *prefix)
185{
186 pr_err("%s by task %u:\n", prefix, track->pid);
187 if (track->stack) {
188 struct stack_trace trace;
189
190 depot_fetch_stack(track->stack, &trace);
191 print_stack_trace(&trace, 0);
192 } else {
193 pr_err("(stack is not available)\n");
194 }
195}
196
197static struct page *addr_to_page(const void *addr)
198{
199 if ((addr >= (void *)PAGE_OFFSET) &&
200 (addr < high_memory))
201 return virt_to_head_page(addr);
202 return NULL;
203}
204
205static void describe_object_addr(struct kmem_cache *cache, void *object,
206 const void *addr)
207{
208 unsigned long access_addr = (unsigned long)addr;
209 unsigned long object_addr = (unsigned long)object;
210 const char *rel_type;
211 int rel_bytes;
212
213 pr_err("The buggy address belongs to the object at %px\n"
214 " which belongs to the cache %s of size %d\n",
215 object, cache->name, cache->object_size);
216
217 if (!addr)
218 return;
219
220 if (access_addr < object_addr) {
221 rel_type = "to the left";
222 rel_bytes = object_addr - access_addr;
223 } else if (access_addr >= object_addr + cache->object_size) {
224 rel_type = "to the right";
225 rel_bytes = access_addr - (object_addr + cache->object_size);
226 } else {
227 rel_type = "inside";
228 rel_bytes = access_addr - object_addr;
229 }
230
231 pr_err("The buggy address is located %d bytes %s of\n"
232 " %d-byte region [%px, %px)\n",
233 rel_bytes, rel_type, cache->object_size, (void *)object_addr,
234 (void *)(object_addr + cache->object_size));
235}
236
237static void describe_object(struct kmem_cache *cache, void *object,
238 const void *addr)
239{
240 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
241
242 if (cache->flags & SLAB_KASAN) {
243 print_track(&alloc_info->alloc_track, "Allocated");
244 pr_err("\n");
245 print_track(&alloc_info->free_track, "Freed");
246 pr_err("\n");
247 }
248
249 describe_object_addr(cache, object, addr);
250}
251
252static void print_address_description(void *addr)
253{
254 struct page *page = addr_to_page(addr);
255
256 dump_stack();
257 pr_err("\n");
258
259 if (page && PageSlab(page)) {
260 struct kmem_cache *cache = page->slab_cache;
261 void *object = nearest_obj(cache, page, addr);
262
263 describe_object(cache, object, addr);
264 }
265
266 if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
267 pr_err("The buggy address belongs to the variable:\n");
268 pr_err(" %pS\n", addr);
269 }
270
271 if (page) {
272 pr_err("The buggy address belongs to the page:\n");
273 dump_page(page, "kasan: bad access detected");
274 }
275}
276
277static bool row_is_guilty(const void *row, const void *guilty)
278{
279 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
280}
281
282static int shadow_pointer_offset(const void *row, const void *shadow)
283{
284
285
286
287 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
288 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
289}
290
291static void print_shadow_for_address(const void *addr)
292{
293 int i;
294 const void *shadow = kasan_mem_to_shadow(addr);
295 const void *shadow_row;
296
297 shadow_row = (void *)round_down((unsigned long)shadow,
298 SHADOW_BYTES_PER_ROW)
299 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
300
301 pr_err("Memory state around the buggy address:\n");
302
303 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
304 const void *kaddr = kasan_shadow_to_mem(shadow_row);
305 char buffer[4 + (BITS_PER_LONG/8)*2];
306 char shadow_buf[SHADOW_BYTES_PER_ROW];
307
308 snprintf(buffer, sizeof(buffer),
309 (i == 0) ? ">%px: " : " %px: ", kaddr);
310
311
312
313
314
315 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
316 print_hex_dump(KERN_ERR, buffer,
317 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
318 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
319
320 if (row_is_guilty(shadow_row, shadow))
321 pr_err("%*c\n",
322 shadow_pointer_offset(shadow_row, shadow),
323 '^');
324
325 shadow_row += SHADOW_BYTES_PER_ROW;
326 }
327}
328
329void kasan_report_invalid_free(void *object, unsigned long ip)
330{
331 unsigned long flags;
332
333 kasan_start_report(&flags);
334 pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
335 pr_err("\n");
336 print_address_description(object);
337 pr_err("\n");
338 print_shadow_for_address(object);
339 kasan_end_report(&flags);
340}
341
342static void kasan_report_error(struct kasan_access_info *info)
343{
344 unsigned long flags;
345
346 kasan_start_report(&flags);
347
348 print_error_description(info);
349 pr_err("\n");
350
351 if (!addr_has_shadow(info)) {
352 dump_stack();
353 } else {
354 print_address_description((void *)info->access_addr);
355 pr_err("\n");
356 print_shadow_for_address(info->first_bad_addr);
357 }
358
359 kasan_end_report(&flags);
360}
361
362static unsigned long kasan_flags;
363
364#define KASAN_BIT_REPORTED 0
365#define KASAN_BIT_MULTI_SHOT 1
366
367bool kasan_save_enable_multi_shot(void)
368{
369 return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
370}
371EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
372
373void kasan_restore_multi_shot(bool enabled)
374{
375 if (!enabled)
376 clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
377}
378EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
379
380static int __init kasan_set_multi_shot(char *str)
381{
382 set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
383 return 1;
384}
385__setup("kasan_multi_shot", kasan_set_multi_shot);
386
387static inline bool kasan_report_enabled(void)
388{
389 if (current->kasan_depth)
390 return false;
391 if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
392 return true;
393 return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
394}
395
396void kasan_report(unsigned long addr, size_t size,
397 bool is_write, unsigned long ip)
398{
399 struct kasan_access_info info;
400
401 if (likely(!kasan_report_enabled()))
402 return;
403
404 disable_trace_on_warning();
405
406 info.access_addr = (void *)addr;
407 info.first_bad_addr = (void *)addr;
408 info.access_size = size;
409 info.is_write = is_write;
410 info.ip = ip;
411
412 kasan_report_error(&info);
413}
414
415
416#define DEFINE_ASAN_REPORT_LOAD(size) \
417void __asan_report_load##size##_noabort(unsigned long addr) \
418{ \
419 kasan_report(addr, size, false, _RET_IP_); \
420} \
421EXPORT_SYMBOL(__asan_report_load##size##_noabort)
422
423#define DEFINE_ASAN_REPORT_STORE(size) \
424void __asan_report_store##size##_noabort(unsigned long addr) \
425{ \
426 kasan_report(addr, size, true, _RET_IP_); \
427} \
428EXPORT_SYMBOL(__asan_report_store##size##_noabort)
429
430DEFINE_ASAN_REPORT_LOAD(1);
431DEFINE_ASAN_REPORT_LOAD(2);
432DEFINE_ASAN_REPORT_LOAD(4);
433DEFINE_ASAN_REPORT_LOAD(8);
434DEFINE_ASAN_REPORT_LOAD(16);
435DEFINE_ASAN_REPORT_STORE(1);
436DEFINE_ASAN_REPORT_STORE(2);
437DEFINE_ASAN_REPORT_STORE(4);
438DEFINE_ASAN_REPORT_STORE(8);
439DEFINE_ASAN_REPORT_STORE(16);
440
441void __asan_report_load_n_noabort(unsigned long addr, size_t size)
442{
443 kasan_report(addr, size, false, _RET_IP_);
444}
445EXPORT_SYMBOL(__asan_report_load_n_noabort);
446
447void __asan_report_store_n_noabort(unsigned long addr, size_t size)
448{
449 kasan_report(addr, size, true, _RET_IP_);
450}
451EXPORT_SYMBOL(__asan_report_store_n_noabort);
452
