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16#include <linux/kernel.h>
17#include <linux/mm.h>
18#include <linux/printk.h>
19#include <linux/sched.h>
20#include <linux/slab.h>
21#include <linux/stackdepot.h>
22#include <linux/stacktrace.h>
23#include <linux/string.h>
24#include <linux/types.h>
25#include <linux/kasan.h>
26#include <linux/module.h>
27
28#include <asm/sections.h>
29
30#include "kasan.h"
31#include "../slab.h"
32
33
34#define SHADOW_BYTES_PER_BLOCK 1
35#define SHADOW_BLOCKS_PER_ROW 16
36#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
37#define SHADOW_ROWS_AROUND_ADDR 2
38
39static const void *find_first_bad_addr(const void *addr, size_t size)
40{
41 u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
42 const void *first_bad_addr = addr;
43
44 while (!shadow_val && first_bad_addr < addr + size) {
45 first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
46 shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
47 }
48 return first_bad_addr;
49}
50
51static void print_error_description(struct kasan_access_info *info)
52{
53 const char *bug_type = "unknown-crash";
54 u8 *shadow_addr;
55
56 info->first_bad_addr = find_first_bad_addr(info->access_addr,
57 info->access_size);
58
59 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
60
61
62
63
64
65 if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
66 shadow_addr++;
67
68 switch (*shadow_addr) {
69 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
70
71
72
73
74 bug_type = "out-of-bounds";
75 break;
76 case KASAN_PAGE_REDZONE:
77 case KASAN_KMALLOC_REDZONE:
78 bug_type = "slab-out-of-bounds";
79 break;
80 case KASAN_GLOBAL_REDZONE:
81 bug_type = "global-out-of-bounds";
82 break;
83 case KASAN_STACK_LEFT:
84 case KASAN_STACK_MID:
85 case KASAN_STACK_RIGHT:
86 case KASAN_STACK_PARTIAL:
87 bug_type = "stack-out-of-bounds";
88 break;
89 case KASAN_FREE_PAGE:
90 case KASAN_KMALLOC_FREE:
91 bug_type = "use-after-free";
92 break;
93 case KASAN_USE_AFTER_SCOPE:
94 bug_type = "use-after-scope";
95 break;
96 }
97
98 pr_err("BUG: KASAN: %s in %pS at addr %p\n",
99 bug_type, (void *)info->ip,
100 info->access_addr);
101 pr_err("%s of size %zu by task %s/%d\n",
102 info->is_write ? "Write" : "Read",
103 info->access_size, current->comm, task_pid_nr(current));
104}
105
106static inline bool kernel_or_module_addr(const void *addr)
107{
108 if (addr >= (void *)_stext && addr < (void *)_end)
109 return true;
110 if (is_module_address((unsigned long)addr))
111 return true;
112 return false;
113}
114
115static inline bool init_task_stack_addr(const void *addr)
116{
117 return addr >= (void *)&init_thread_union.stack &&
118 (addr <= (void *)&init_thread_union.stack +
119 sizeof(init_thread_union.stack));
120}
121
122static DEFINE_SPINLOCK(report_lock);
123
124static void kasan_start_report(unsigned long *flags)
125{
126
127
128
129 kasan_disable_current();
130 spin_lock_irqsave(&report_lock, *flags);
131 pr_err("==================================================================\n");
132}
133
134static void kasan_end_report(unsigned long *flags)
135{
136 pr_err("==================================================================\n");
137 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
138 spin_unlock_irqrestore(&report_lock, *flags);
139 kasan_enable_current();
140}
141
142static void print_track(struct kasan_track *track)
143{
144 pr_err("PID = %u\n", track->pid);
145 if (track->stack) {
146 struct stack_trace trace;
147
148 depot_fetch_stack(track->stack, &trace);
149 print_stack_trace(&trace, 0);
150 } else {
151 pr_err("(stack is not available)\n");
152 }
153}
154
155static void kasan_object_err(struct kmem_cache *cache, void *object)
156{
157 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
158
159 dump_stack();
160 pr_err("Object at %p, in cache %s size: %d\n", object, cache->name,
161 cache->object_size);
162
163 if (!(cache->flags & SLAB_KASAN))
164 return;
165
166 pr_err("Allocated:\n");
167 print_track(&alloc_info->alloc_track);
168 pr_err("Freed:\n");
169 print_track(&alloc_info->free_track);
170}
171
172void kasan_report_double_free(struct kmem_cache *cache, void *object,
173 s8 shadow)
174{
175 unsigned long flags;
176
177 kasan_start_report(&flags);
178 pr_err("BUG: Double free or freeing an invalid pointer\n");
179 pr_err("Unexpected shadow byte: 0x%hhX\n", shadow);
180 kasan_object_err(cache, object);
181 kasan_end_report(&flags);
182}
183
184static void print_address_description(struct kasan_access_info *info)
185{
186 const void *addr = info->access_addr;
187
188 if ((addr >= (void *)PAGE_OFFSET) &&
189 (addr < high_memory)) {
190 struct page *page = virt_to_head_page(addr);
191
192 if (PageSlab(page)) {
193 void *object;
194 struct kmem_cache *cache = page->slab_cache;
195 object = nearest_obj(cache, page,
196 (void *)info->access_addr);
197 kasan_object_err(cache, object);
198 return;
199 }
200 dump_page(page, "kasan: bad access detected");
201 }
202
203 if (kernel_or_module_addr(addr)) {
204 if (!init_task_stack_addr(addr))
205 pr_err("Address belongs to variable %pS\n", addr);
206 }
207 dump_stack();
208}
209
210static bool row_is_guilty(const void *row, const void *guilty)
211{
212 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
213}
214
215static int shadow_pointer_offset(const void *row, const void *shadow)
216{
217
218
219
220 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
221 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
222}
223
224static void print_shadow_for_address(const void *addr)
225{
226 int i;
227 const void *shadow = kasan_mem_to_shadow(addr);
228 const void *shadow_row;
229
230 shadow_row = (void *)round_down((unsigned long)shadow,
231 SHADOW_BYTES_PER_ROW)
232 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
233
234 pr_err("Memory state around the buggy address:\n");
235
236 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
237 const void *kaddr = kasan_shadow_to_mem(shadow_row);
238 char buffer[4 + (BITS_PER_LONG/8)*2];
239 char shadow_buf[SHADOW_BYTES_PER_ROW];
240
241 snprintf(buffer, sizeof(buffer),
242 (i == 0) ? ">%p: " : " %p: ", kaddr);
243
244
245
246
247
248 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
249 print_hex_dump(KERN_ERR, buffer,
250 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
251 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
252
253 if (row_is_guilty(shadow_row, shadow))
254 pr_err("%*c\n",
255 shadow_pointer_offset(shadow_row, shadow),
256 '^');
257
258 shadow_row += SHADOW_BYTES_PER_ROW;
259 }
260}
261
262static void kasan_report_error(struct kasan_access_info *info)
263{
264 unsigned long flags;
265 const char *bug_type;
266
267 kasan_start_report(&flags);
268
269 if (info->access_addr <
270 kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
271 if ((unsigned long)info->access_addr < PAGE_SIZE)
272 bug_type = "null-ptr-deref";
273 else if ((unsigned long)info->access_addr < TASK_SIZE)
274 bug_type = "user-memory-access";
275 else
276 bug_type = "wild-memory-access";
277 pr_err("BUG: KASAN: %s on address %p\n",
278 bug_type, info->access_addr);
279 pr_err("%s of size %zu by task %s/%d\n",
280 info->is_write ? "Write" : "Read",
281 info->access_size, current->comm,
282 task_pid_nr(current));
283 dump_stack();
284 } else {
285 print_error_description(info);
286 print_address_description(info);
287 print_shadow_for_address(info->first_bad_addr);
288 }
289
290 kasan_end_report(&flags);
291}
292
293void kasan_report(unsigned long addr, size_t size,
294 bool is_write, unsigned long ip)
295{
296 struct kasan_access_info info;
297
298 if (likely(!kasan_report_enabled()))
299 return;
300
301 info.access_addr = (void *)addr;
302 info.access_size = size;
303 info.is_write = is_write;
304 info.ip = ip;
305
306 kasan_report_error(&info);
307}
308
309
310#define DEFINE_ASAN_REPORT_LOAD(size) \
311void __asan_report_load##size##_noabort(unsigned long addr) \
312{ \
313 kasan_report(addr, size, false, _RET_IP_); \
314} \
315EXPORT_SYMBOL(__asan_report_load##size##_noabort)
316
317#define DEFINE_ASAN_REPORT_STORE(size) \
318void __asan_report_store##size##_noabort(unsigned long addr) \
319{ \
320 kasan_report(addr, size, true, _RET_IP_); \
321} \
322EXPORT_SYMBOL(__asan_report_store##size##_noabort)
323
324DEFINE_ASAN_REPORT_LOAD(1);
325DEFINE_ASAN_REPORT_LOAD(2);
326DEFINE_ASAN_REPORT_LOAD(4);
327DEFINE_ASAN_REPORT_LOAD(8);
328DEFINE_ASAN_REPORT_LOAD(16);
329DEFINE_ASAN_REPORT_STORE(1);
330DEFINE_ASAN_REPORT_STORE(2);
331DEFINE_ASAN_REPORT_STORE(4);
332DEFINE_ASAN_REPORT_STORE(8);
333DEFINE_ASAN_REPORT_STORE(16);
334
335void __asan_report_load_n_noabort(unsigned long addr, size_t size)
336{
337 kasan_report(addr, size, false, _RET_IP_);
338}
339EXPORT_SYMBOL(__asan_report_load_n_noabort);
340
341void __asan_report_store_n_noabort(unsigned long addr, size_t size)
342{
343 kasan_report(addr, size, true, _RET_IP_);
344}
345EXPORT_SYMBOL(__asan_report_store_n_noabort);
346
