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13#include <linux/bitops.h>
14#include <linux/bug.h>
15#include <linux/ctype.h>
16#include <linux/init.h>
17#include <linux/kernel.h>
18#include <linux/types.h>
19#include <linux/sched.h>
20#include <linux/uaccess.h>
21
22#include "ubsan.h"
23
24const char *type_check_kinds[] = {
25 "load of",
26 "store to",
27 "reference binding to",
28 "member access within",
29 "member call on",
30 "constructor call on",
31 "downcast of",
32 "downcast of"
33};
34
35#define REPORTED_BIT 31
36
37#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
38#define COLUMN_MASK (~(1U << REPORTED_BIT))
39#define LINE_MASK (~0U)
40#else
41#define COLUMN_MASK (~0U)
42#define LINE_MASK (~(1U << REPORTED_BIT))
43#endif
44
45#define VALUE_LENGTH 40
46
47static bool was_reported(struct source_location *location)
48{
49 return test_and_set_bit(REPORTED_BIT, &location->reported);
50}
51
52static void print_source_location(const char *prefix,
53 struct source_location *loc)
54{
55 pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
56 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
57}
58
59static bool suppress_report(struct source_location *loc)
60{
61 return current->in_ubsan || was_reported(loc);
62}
63
64static bool type_is_int(struct type_descriptor *type)
65{
66 return type->type_kind == type_kind_int;
67}
68
69static bool type_is_signed(struct type_descriptor *type)
70{
71 WARN_ON(!type_is_int(type));
72 return type->type_info & 1;
73}
74
75static unsigned type_bit_width(struct type_descriptor *type)
76{
77 return 1 << (type->type_info >> 1);
78}
79
80static bool is_inline_int(struct type_descriptor *type)
81{
82 unsigned inline_bits = sizeof(unsigned long)*8;
83 unsigned bits = type_bit_width(type);
84
85 WARN_ON(!type_is_int(type));
86
87 return bits <= inline_bits;
88}
89
90static s_max get_signed_val(struct type_descriptor *type, unsigned long val)
91{
92 if (is_inline_int(type)) {
93 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
94 return ((s_max)val) << extra_bits >> extra_bits;
95 }
96
97 if (type_bit_width(type) == 64)
98 return *(s64 *)val;
99
100 return *(s_max *)val;
101}
102
103static bool val_is_negative(struct type_descriptor *type, unsigned long val)
104{
105 return type_is_signed(type) && get_signed_val(type, val) < 0;
106}
107
108static u_max get_unsigned_val(struct type_descriptor *type, unsigned long val)
109{
110 if (is_inline_int(type))
111 return val;
112
113 if (type_bit_width(type) == 64)
114 return *(u64 *)val;
115
116 return *(u_max *)val;
117}
118
119static void val_to_string(char *str, size_t size, struct type_descriptor *type,
120 unsigned long value)
121{
122 if (type_is_int(type)) {
123 if (type_bit_width(type) == 128) {
124#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
125 u_max val = get_unsigned_val(type, value);
126
127 scnprintf(str, size, "0x%08x%08x%08x%08x",
128 (u32)(val >> 96),
129 (u32)(val >> 64),
130 (u32)(val >> 32),
131 (u32)(val));
132#else
133 WARN_ON(1);
134#endif
135 } else if (type_is_signed(type)) {
136 scnprintf(str, size, "%lld",
137 (s64)get_signed_val(type, value));
138 } else {
139 scnprintf(str, size, "%llu",
140 (u64)get_unsigned_val(type, value));
141 }
142 }
143}
144
145static void ubsan_prologue(struct source_location *location)
146{
147 current->in_ubsan++;
148
149 pr_err("========================================"
150 "========================================\n");
151 print_source_location("UBSAN: Undefined behaviour in", location);
152}
153
154static void ubsan_epilogue(void)
155{
156 dump_stack();
157 pr_err("========================================"
158 "========================================\n");
159
160 current->in_ubsan--;
161}
162
163static void handle_overflow(struct overflow_data *data, unsigned long lhs,
164 unsigned long rhs, char op)
165{
166
167 struct type_descriptor *type = data->type;
168 char lhs_val_str[VALUE_LENGTH];
169 char rhs_val_str[VALUE_LENGTH];
170
171 if (suppress_report(&data->location))
172 return;
173
174 ubsan_prologue(&data->location);
175
176 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
177 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
178 pr_err("%s integer overflow:\n",
179 type_is_signed(type) ? "signed" : "unsigned");
180 pr_err("%s %c %s cannot be represented in type %s\n",
181 lhs_val_str,
182 op,
183 rhs_val_str,
184 type->type_name);
185
186 ubsan_epilogue();
187}
188
189void __ubsan_handle_add_overflow(struct overflow_data *data,
190 unsigned long lhs,
191 unsigned long rhs)
192{
193
194 handle_overflow(data, lhs, rhs, '+');
195}
196EXPORT_SYMBOL(__ubsan_handle_add_overflow);
197
198void __ubsan_handle_sub_overflow(struct overflow_data *data,
199 unsigned long lhs,
200 unsigned long rhs)
201{
202 handle_overflow(data, lhs, rhs, '-');
203}
204EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
205
206void __ubsan_handle_mul_overflow(struct overflow_data *data,
207 unsigned long lhs,
208 unsigned long rhs)
209{
210 handle_overflow(data, lhs, rhs, '*');
211}
212EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
213
214void __ubsan_handle_negate_overflow(struct overflow_data *data,
215 unsigned long old_val)
216{
217 char old_val_str[VALUE_LENGTH];
218
219 if (suppress_report(&data->location))
220 return;
221
222 ubsan_prologue(&data->location);
223
224 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
225
226 pr_err("negation of %s cannot be represented in type %s:\n",
227 old_val_str, data->type->type_name);
228
229 ubsan_epilogue();
230}
231EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
232
233
234void __ubsan_handle_divrem_overflow(struct overflow_data *data,
235 unsigned long lhs,
236 unsigned long rhs)
237{
238 char rhs_val_str[VALUE_LENGTH];
239
240 if (suppress_report(&data->location))
241 return;
242
243 ubsan_prologue(&data->location);
244
245 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
246
247 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
248 pr_err("division of %s by -1 cannot be represented in type %s\n",
249 rhs_val_str, data->type->type_name);
250 else
251 pr_err("division by zero\n");
252
253 ubsan_epilogue();
254}
255EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
256
257static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
258{
259 if (suppress_report(data->location))
260 return;
261
262 ubsan_prologue(data->location);
263
264 pr_err("%s null pointer of type %s\n",
265 type_check_kinds[data->type_check_kind],
266 data->type->type_name);
267
268 ubsan_epilogue();
269}
270
271static void handle_misaligned_access(struct type_mismatch_data_common *data,
272 unsigned long ptr)
273{
274 if (suppress_report(data->location))
275 return;
276
277 ubsan_prologue(data->location);
278
279 pr_err("%s misaligned address %p for type %s\n",
280 type_check_kinds[data->type_check_kind],
281 (void *)ptr, data->type->type_name);
282 pr_err("which requires %ld byte alignment\n", data->alignment);
283
284 ubsan_epilogue();
285}
286
287static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
288 unsigned long ptr)
289{
290 if (suppress_report(data->location))
291 return;
292
293 ubsan_prologue(data->location);
294 pr_err("%s address %p with insufficient space\n",
295 type_check_kinds[data->type_check_kind],
296 (void *) ptr);
297 pr_err("for an object of type %s\n", data->type->type_name);
298 ubsan_epilogue();
299}
300
301static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
302 unsigned long ptr)
303{
304 unsigned long flags = user_access_save();
305
306 if (!ptr)
307 handle_null_ptr_deref(data);
308 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
309 handle_misaligned_access(data, ptr);
310 else
311 handle_object_size_mismatch(data, ptr);
312
313 user_access_restore(flags);
314}
315
316void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
317 unsigned long ptr)
318{
319 struct type_mismatch_data_common common_data = {
320 .location = &data->location,
321 .type = data->type,
322 .alignment = data->alignment,
323 .type_check_kind = data->type_check_kind
324 };
325
326 ubsan_type_mismatch_common(&common_data, ptr);
327}
328EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
329
330void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
331 unsigned long ptr)
332{
333
334 struct type_mismatch_data_common common_data = {
335 .location = &data->location,
336 .type = data->type,
337 .alignment = 1UL << data->log_alignment,
338 .type_check_kind = data->type_check_kind
339 };
340
341 ubsan_type_mismatch_common(&common_data, ptr);
342}
343EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
344
345void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data,
346 unsigned long bound)
347{
348 char bound_str[VALUE_LENGTH];
349
350 if (suppress_report(&data->location))
351 return;
352
353 ubsan_prologue(&data->location);
354
355 val_to_string(bound_str, sizeof(bound_str), data->type, bound);
356 pr_err("variable length array bound value %s <= 0\n", bound_str);
357
358 ubsan_epilogue();
359}
360EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive);
361
362void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data,
363 unsigned long index)
364{
365 char index_str[VALUE_LENGTH];
366
367 if (suppress_report(&data->location))
368 return;
369
370 ubsan_prologue(&data->location);
371
372 val_to_string(index_str, sizeof(index_str), data->index_type, index);
373 pr_err("index %s is out of range for type %s\n", index_str,
374 data->array_type->type_name);
375 ubsan_epilogue();
376}
377EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
378
379void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
380 unsigned long lhs, unsigned long rhs)
381{
382 struct type_descriptor *rhs_type = data->rhs_type;
383 struct type_descriptor *lhs_type = data->lhs_type;
384 char rhs_str[VALUE_LENGTH];
385 char lhs_str[VALUE_LENGTH];
386 unsigned long ua_flags = user_access_save();
387
388 if (suppress_report(&data->location))
389 goto out;
390
391 ubsan_prologue(&data->location);
392
393 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
394 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
395
396 if (val_is_negative(rhs_type, rhs))
397 pr_err("shift exponent %s is negative\n", rhs_str);
398
399 else if (get_unsigned_val(rhs_type, rhs) >=
400 type_bit_width(lhs_type))
401 pr_err("shift exponent %s is too large for %u-bit type %s\n",
402 rhs_str,
403 type_bit_width(lhs_type),
404 lhs_type->type_name);
405 else if (val_is_negative(lhs_type, lhs))
406 pr_err("left shift of negative value %s\n",
407 lhs_str);
408 else
409 pr_err("left shift of %s by %s places cannot be"
410 " represented in type %s\n",
411 lhs_str, rhs_str,
412 lhs_type->type_name);
413
414 ubsan_epilogue();
415out:
416 user_access_restore(ua_flags);
417}
418EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
419
420
421void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
422{
423 ubsan_prologue(&data->location);
424 pr_err("calling __builtin_unreachable()\n");
425 ubsan_epilogue();
426 panic("can't return from __builtin_unreachable()");
427}
428EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
429
430void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
431 unsigned long val)
432{
433 char val_str[VALUE_LENGTH];
434
435 if (suppress_report(&data->location))
436 return;
437
438 ubsan_prologue(&data->location);
439
440 val_to_string(val_str, sizeof(val_str), data->type, val);
441
442 pr_err("load of value %s is not a valid value for type %s\n",
443 val_str, data->type->type_name);
444
445 ubsan_epilogue();
446}
447EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
448
