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