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16#include <linux/ftrace.h>
17#include <linux/kernel.h>
18#include <linux/mm.h>
19#include <linux/printk.h>
20#include <linux/sched.h>
21#include <linux/slab.h>
22#include <linux/stackdepot.h>
23#include <linux/stacktrace.h>
24#include <linux/string.h>
25#include <linux/types.h>
26#include <linux/kasan.h>
27#include <linux/module.h>
28
29#include <asm/sections.h>
30
31#include "kasan.h"
32#include "../slab.h"
33
34
35#define SHADOW_BYTES_PER_BLOCK 1
36#define SHADOW_BLOCKS_PER_ROW 16
37#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
38#define SHADOW_ROWS_AROUND_ADDR 2
39
40static const void *find_first_bad_addr(const void *addr, size_t size)
41{
42 u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
43 const void *first_bad_addr = addr;
44
45 while (!shadow_val && first_bad_addr < addr + size) {
46 first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
47 shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
48 }
49 return first_bad_addr;
50}
51
52static void print_error_description(struct kasan_access_info *info)
53{
54 const char *bug_type = "unknown-crash";
55 u8 *shadow_addr;
56
57 info->first_bad_addr = find_first_bad_addr(info->access_addr,
58 info->access_size);
59
60 shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
61
62
63
64
65
66 if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
67 shadow_addr++;
68
69 switch (*shadow_addr) {
70 case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
71
72
73
74
75 bug_type = "out-of-bounds";
76 break;
77 case KASAN_PAGE_REDZONE:
78 case KASAN_KMALLOC_REDZONE:
79 bug_type = "slab-out-of-bounds";
80 break;
81 case KASAN_GLOBAL_REDZONE:
82 bug_type = "global-out-of-bounds";
83 break;
84 case KASAN_STACK_LEFT:
85 case KASAN_STACK_MID:
86 case KASAN_STACK_RIGHT:
87 case KASAN_STACK_PARTIAL:
88 bug_type = "stack-out-of-bounds";
89 break;
90 case KASAN_FREE_PAGE:
91 case KASAN_KMALLOC_FREE:
92 bug_type = "use-after-free";
93 break;
94 case KASAN_USE_AFTER_SCOPE:
95 bug_type = "use-after-scope";
96 break;
97 }
98
99 pr_err("BUG: KASAN: %s in %pS at addr %p\n",
100 bug_type, (void *)info->ip,
101 info->access_addr);
102 pr_err("%s of size %zu by task %s/%d\n",
103 info->is_write ? "Write" : "Read",
104 info->access_size, current->comm, task_pid_nr(current));
105}
106
107static inline bool kernel_or_module_addr(const void *addr)
108{
109 if (addr >= (void *)_stext && addr < (void *)_end)
110 return true;
111 if (is_module_address((unsigned long)addr))
112 return true;
113 return false;
114}
115
116static inline bool init_task_stack_addr(const void *addr)
117{
118 return addr >= (void *)&init_thread_union.stack &&
119 (addr <= (void *)&init_thread_union.stack +
120 sizeof(init_thread_union.stack));
121}
122
123static DEFINE_SPINLOCK(report_lock);
124
125static void kasan_start_report(unsigned long *flags)
126{
127
128
129
130 kasan_disable_current();
131 spin_lock_irqsave(&report_lock, *flags);
132 pr_err("==================================================================\n");
133}
134
135static void kasan_end_report(unsigned long *flags)
136{
137 pr_err("==================================================================\n");
138 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
139 spin_unlock_irqrestore(&report_lock, *flags);
140 if (panic_on_warn)
141 panic("panic_on_warn set ...\n");
142 kasan_enable_current();
143}
144
145static void print_track(struct kasan_track *track)
146{
147 pr_err("PID = %u\n", track->pid);
148 if (track->stack) {
149 struct stack_trace trace;
150
151 depot_fetch_stack(track->stack, &trace);
152 print_stack_trace(&trace, 0);
153 } else {
154 pr_err("(stack is not available)\n");
155 }
156}
157
158static void kasan_object_err(struct kmem_cache *cache, void *object)
159{
160 struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
161
162 dump_stack();
163 pr_err("Object at %p, in cache %s size: %d\n", object, cache->name,
164 cache->object_size);
165
166 if (!(cache->flags & SLAB_KASAN))
167 return;
168
169 pr_err("Allocated:\n");
170 print_track(&alloc_info->alloc_track);
171 pr_err("Freed:\n");
172 print_track(&alloc_info->free_track);
173}
174
175void kasan_report_double_free(struct kmem_cache *cache, void *object,
176 s8 shadow)
177{
178 unsigned long flags;
179
180 kasan_start_report(&flags);
181 pr_err("BUG: Double free or freeing an invalid pointer\n");
182 pr_err("Unexpected shadow byte: 0x%hhX\n", shadow);
183 kasan_object_err(cache, object);
184 kasan_end_report(&flags);
185}
186
187static void print_address_description(struct kasan_access_info *info)
188{
189 const void *addr = info->access_addr;
190
191 if ((addr >= (void *)PAGE_OFFSET) &&
192 (addr < high_memory)) {
193 struct page *page = virt_to_head_page(addr);
194
195 if (PageSlab(page)) {
196 void *object;
197 struct kmem_cache *cache = page->slab_cache;
198 object = nearest_obj(cache, page,
199 (void *)info->access_addr);
200 kasan_object_err(cache, object);
201 return;
202 }
203 dump_page(page, "kasan: bad access detected");
204 }
205
206 if (kernel_or_module_addr(addr)) {
207 if (!init_task_stack_addr(addr))
208 pr_err("Address belongs to variable %pS\n", addr);
209 }
210 dump_stack();
211}
212
213static bool row_is_guilty(const void *row, const void *guilty)
214{
215 return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
216}
217
218static int shadow_pointer_offset(const void *row, const void *shadow)
219{
220
221
222
223 return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
224 (shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
225}
226
227static void print_shadow_for_address(const void *addr)
228{
229 int i;
230 const void *shadow = kasan_mem_to_shadow(addr);
231 const void *shadow_row;
232
233 shadow_row = (void *)round_down((unsigned long)shadow,
234 SHADOW_BYTES_PER_ROW)
235 - SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
236
237 pr_err("Memory state around the buggy address:\n");
238
239 for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
240 const void *kaddr = kasan_shadow_to_mem(shadow_row);
241 char buffer[4 + (BITS_PER_LONG/8)*2];
242 char shadow_buf[SHADOW_BYTES_PER_ROW];
243
244 snprintf(buffer, sizeof(buffer),
245 (i == 0) ? ">%p: " : " %p: ", kaddr);
246
247
248
249
250
251 memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
252 print_hex_dump(KERN_ERR, buffer,
253 DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
254 shadow_buf, SHADOW_BYTES_PER_ROW, 0);
255
256 if (row_is_guilty(shadow_row, shadow))
257 pr_err("%*c\n",
258 shadow_pointer_offset(shadow_row, shadow),
259 '^');
260
261 shadow_row += SHADOW_BYTES_PER_ROW;
262 }
263}
264
265static void kasan_report_error(struct kasan_access_info *info)
266{
267 unsigned long flags;
268 const char *bug_type;
269
270 kasan_start_report(&flags);
271
272 if (info->access_addr <
273 kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
274 if ((unsigned long)info->access_addr < PAGE_SIZE)
275 bug_type = "null-ptr-deref";
276 else if ((unsigned long)info->access_addr < TASK_SIZE)
277 bug_type = "user-memory-access";
278 else
279 bug_type = "wild-memory-access";
280 pr_err("BUG: KASAN: %s on address %p\n",
281 bug_type, info->access_addr);
282 pr_err("%s of size %zu by task %s/%d\n",
283 info->is_write ? "Write" : "Read",
284 info->access_size, current->comm,
285 task_pid_nr(current));
286 dump_stack();
287 } else {
288 print_error_description(info);
289 print_address_description(info);
290 print_shadow_for_address(info->first_bad_addr);
291 }
292
293 kasan_end_report(&flags);
294}
295
296void kasan_report(unsigned long addr, size_t size,
297 bool is_write, unsigned long ip)
298{
299 struct kasan_access_info info;
300
301 if (likely(!kasan_report_enabled()))
302 return;
303
304 disable_trace_on_warning();
305
306 info.access_addr = (void *)addr;
307 info.access_size = size;
308 info.is_write = is_write;
309 info.ip = ip;
310
311 kasan_report_error(&info);
312}
313
314
315#define DEFINE_ASAN_REPORT_LOAD(size) \
316void __asan_report_load##size##_noabort(unsigned long addr) \
317{ \
318 kasan_report(addr, size, false, _RET_IP_); \
319} \
320EXPORT_SYMBOL(__asan_report_load##size##_noabort)
321
322#define DEFINE_ASAN_REPORT_STORE(size) \
323void __asan_report_store##size##_noabort(unsigned long addr) \
324{ \
325 kasan_report(addr, size, true, _RET_IP_); \
326} \
327EXPORT_SYMBOL(__asan_report_store##size##_noabort)
328
329DEFINE_ASAN_REPORT_LOAD(1);
330DEFINE_ASAN_REPORT_LOAD(2);
331DEFINE_ASAN_REPORT_LOAD(4);
332DEFINE_ASAN_REPORT_LOAD(8);
333DEFINE_ASAN_REPORT_LOAD(16);
334DEFINE_ASAN_REPORT_STORE(1);
335DEFINE_ASAN_REPORT_STORE(2);
336DEFINE_ASAN_REPORT_STORE(4);
337DEFINE_ASAN_REPORT_STORE(8);
338DEFINE_ASAN_REPORT_STORE(16);
339
340void __asan_report_load_n_noabort(unsigned long addr, size_t size)
341{
342 kasan_report(addr, size, false, _RET_IP_);
343}
344EXPORT_SYMBOL(__asan_report_load_n_noabort);
345
346void __asan_report_store_n_noabort(unsigned long addr, size_t size)
347{
348 kasan_report(addr, size, true, _RET_IP_);
349}
350EXPORT_SYMBOL(__asan_report_store_n_noabort);
351
