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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
21#include "ubsan.h"
22
23const char *type_check_kinds[] = {
24 "load of",
25 "store to",
26 "reference binding to",
27 "member access within",
28 "member call on",
29 "constructor call on",
30 "downcast of",
31 "downcast of"
32};
33
34#define REPORTED_BIT 31
35
36#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
37#define COLUMN_MASK (~(1U << REPORTED_BIT))
38#define LINE_MASK (~0U)
39#else
40#define COLUMN_MASK (~0U)
41#define LINE_MASK (~(1U << REPORTED_BIT))
42#endif
43
44#define VALUE_LENGTH 40
45
46static bool was_reported(struct source_location *location)
47{
48 return test_and_set_bit(REPORTED_BIT, &location->reported);
49}
50
51static void print_source_location(const char *prefix,
52 struct source_location *loc)
53{
54 pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
55 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
56}
57
58static bool suppress_report(struct source_location *loc)
59{
60 return current->in_ubsan || was_reported(loc);
61}
62
63static bool type_is_int(struct type_descriptor *type)
64{
65 return type->type_kind == type_kind_int;
66}
67
68static bool type_is_signed(struct type_descriptor *type)
69{
70 WARN_ON(!type_is_int(type));
71 return type->type_info & 1;
72}
73
74static unsigned type_bit_width(struct type_descriptor *type)
75{
76 return 1 << (type->type_info >> 1);
77}
78
79static bool is_inline_int(struct type_descriptor *type)
80{
81 unsigned inline_bits = sizeof(unsigned long)*8;
82 unsigned bits = type_bit_width(type);
83
84 WARN_ON(!type_is_int(type));
85
86 return bits <= inline_bits;
87}
88
89static s_max get_signed_val(struct type_descriptor *type, unsigned long val)
90{
91 if (is_inline_int(type)) {
92 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
93 return ((s_max)val) << extra_bits >> extra_bits;
94 }
95
96 if (type_bit_width(type) == 64)
97 return *(s64 *)val;
98
99 return *(s_max *)val;
100}
101
102static bool val_is_negative(struct type_descriptor *type, unsigned long val)
103{
104 return type_is_signed(type) && get_signed_val(type, val) < 0;
105}
106
107static u_max get_unsigned_val(struct type_descriptor *type, unsigned long val)
108{
109 if (is_inline_int(type))
110 return val;
111
112 if (type_bit_width(type) == 64)
113 return *(u64 *)val;
114
115 return *(u_max *)val;
116}
117
118static void val_to_string(char *str, size_t size, struct type_descriptor *type,
119 unsigned long value)
120{
121 if (type_is_int(type)) {
122 if (type_bit_width(type) == 128) {
123#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
124 u_max val = get_unsigned_val(type, value);
125
126 scnprintf(str, size, "0x%08x%08x%08x%08x",
127 (u32)(val >> 96),
128 (u32)(val >> 64),
129 (u32)(val >> 32),
130 (u32)(val));
131#else
132 WARN_ON(1);
133#endif
134 } else if (type_is_signed(type)) {
135 scnprintf(str, size, "%lld",
136 (s64)get_signed_val(type, value));
137 } else {
138 scnprintf(str, size, "%llu",
139 (u64)get_unsigned_val(type, value));
140 }
141 }
142}
143
144static bool location_is_valid(struct source_location *loc)
145{
146 return loc->file_name != NULL;
147}
148
149static DEFINE_SPINLOCK(report_lock);
150
151static void ubsan_prologue(struct source_location *location,
152 unsigned long *flags)
153{
154 current->in_ubsan++;
155 spin_lock_irqsave(&report_lock, *flags);
156
157 pr_err("========================================"
158 "========================================\n");
159 print_source_location("UBSAN: Undefined behaviour in", location);
160}
161
162static void ubsan_epilogue(unsigned long *flags)
163{
164 dump_stack();
165 pr_err("========================================"
166 "========================================\n");
167 spin_unlock_irqrestore(&report_lock, *flags);
168 current->in_ubsan--;
169}
170
171static void handle_overflow(struct overflow_data *data, unsigned long lhs,
172 unsigned long rhs, char op)
173{
174
175 struct type_descriptor *type = data->type;
176 unsigned long flags;
177 char lhs_val_str[VALUE_LENGTH];
178 char rhs_val_str[VALUE_LENGTH];
179
180 if (suppress_report(&data->location))
181 return;
182
183 ubsan_prologue(&data->location, &flags);
184
185 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
186 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
187 pr_err("%s integer overflow:\n",
188 type_is_signed(type) ? "signed" : "unsigned");
189 pr_err("%s %c %s cannot be represented in type %s\n",
190 lhs_val_str,
191 op,
192 rhs_val_str,
193 type->type_name);
194
195 ubsan_epilogue(&flags);
196}
197
198void __ubsan_handle_add_overflow(struct overflow_data *data,
199 unsigned long lhs,
200 unsigned long rhs)
201{
202
203 handle_overflow(data, lhs, rhs, '+');
204}
205EXPORT_SYMBOL(__ubsan_handle_add_overflow);
206
207void __ubsan_handle_sub_overflow(struct overflow_data *data,
208 unsigned long lhs,
209 unsigned long rhs)
210{
211 handle_overflow(data, lhs, rhs, '-');
212}
213EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
214
215void __ubsan_handle_mul_overflow(struct overflow_data *data,
216 unsigned long lhs,
217 unsigned long rhs)
218{
219 handle_overflow(data, lhs, rhs, '*');
220}
221EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
222
223void __ubsan_handle_negate_overflow(struct overflow_data *data,
224 unsigned long old_val)
225{
226 unsigned long flags;
227 char old_val_str[VALUE_LENGTH];
228
229 if (suppress_report(&data->location))
230 return;
231
232 ubsan_prologue(&data->location, &flags);
233
234 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
235
236 pr_err("negation of %s cannot be represented in type %s:\n",
237 old_val_str, data->type->type_name);
238
239 ubsan_epilogue(&flags);
240}
241EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
242
243
244void __ubsan_handle_divrem_overflow(struct overflow_data *data,
245 unsigned long lhs,
246 unsigned long rhs)
247{
248 unsigned long flags;
249 char rhs_val_str[VALUE_LENGTH];
250
251 if (suppress_report(&data->location))
252 return;
253
254 ubsan_prologue(&data->location, &flags);
255
256 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
257
258 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
259 pr_err("division of %s by -1 cannot be represented in type %s\n",
260 rhs_val_str, data->type->type_name);
261 else
262 pr_err("division by zero\n");
263
264 ubsan_epilogue(&flags);
265}
266EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
267
268static void handle_null_ptr_deref(struct type_mismatch_data *data)
269{
270 unsigned long flags;
271
272 if (suppress_report(&data->location))
273 return;
274
275 ubsan_prologue(&data->location, &flags);
276
277 pr_err("%s null pointer of type %s\n",
278 type_check_kinds[data->type_check_kind],
279 data->type->type_name);
280
281 ubsan_epilogue(&flags);
282}
283
284static void handle_missaligned_access(struct type_mismatch_data *data,
285 unsigned long ptr)
286{
287 unsigned long flags;
288
289 if (suppress_report(&data->location))
290 return;
291
292 ubsan_prologue(&data->location, &flags);
293
294 pr_err("%s misaligned address %p for type %s\n",
295 type_check_kinds[data->type_check_kind],
296 (void *)ptr, data->type->type_name);
297 pr_err("which requires %ld byte alignment\n", data->alignment);
298
299 ubsan_epilogue(&flags);
300}
301
302static void handle_object_size_mismatch(struct type_mismatch_data *data,
303 unsigned long ptr)
304{
305 unsigned long flags;
306
307 if (suppress_report(&data->location))
308 return;
309
310 ubsan_prologue(&data->location, &flags);
311 pr_err("%s address %pk with insufficient space\n",
312 type_check_kinds[data->type_check_kind],
313 (void *) ptr);
314 pr_err("for an object of type %s\n", data->type->type_name);
315 ubsan_epilogue(&flags);
316}
317
318void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
319 unsigned long ptr)
320{
321
322 if (!ptr)
323 handle_null_ptr_deref(data);
324 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
325 handle_missaligned_access(data, ptr);
326 else
327 handle_object_size_mismatch(data, ptr);
328}
329EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
330
331void __ubsan_handle_nonnull_return(struct nonnull_return_data *data)
332{
333 unsigned long flags;
334
335 if (suppress_report(&data->location))
336 return;
337
338 ubsan_prologue(&data->location, &flags);
339
340 pr_err("null pointer returned from function declared to never return null\n");
341
342 if (location_is_valid(&data->attr_location))
343 print_source_location("returns_nonnull attribute specified in",
344 &data->attr_location);
345
346 ubsan_epilogue(&flags);
347}
348EXPORT_SYMBOL(__ubsan_handle_nonnull_return);
349
350void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data,
351 unsigned long bound)
352{
353 unsigned long flags;
354 char bound_str[VALUE_LENGTH];
355
356 if (suppress_report(&data->location))
357 return;
358
359 ubsan_prologue(&data->location, &flags);
360
361 val_to_string(bound_str, sizeof(bound_str), data->type, bound);
362 pr_err("variable length array bound value %s <= 0\n", bound_str);
363
364 ubsan_epilogue(&flags);
365}
366EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive);
367
368void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data,
369 unsigned long index)
370{
371 unsigned long flags;
372 char index_str[VALUE_LENGTH];
373
374 if (suppress_report(&data->location))
375 return;
376
377 ubsan_prologue(&data->location, &flags);
378
379 val_to_string(index_str, sizeof(index_str), data->index_type, index);
380 pr_err("index %s is out of range for type %s\n", index_str,
381 data->array_type->type_name);
382 ubsan_epilogue(&flags);
383}
384EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
385
386void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
387 unsigned long lhs, unsigned long rhs)
388{
389 unsigned long flags;
390 struct type_descriptor *rhs_type = data->rhs_type;
391 struct type_descriptor *lhs_type = data->lhs_type;
392 char rhs_str[VALUE_LENGTH];
393 char lhs_str[VALUE_LENGTH];
394
395 if (suppress_report(&data->location))
396 return;
397
398 ubsan_prologue(&data->location, &flags);
399
400 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
401 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
402
403 if (val_is_negative(rhs_type, rhs))
404 pr_err("shift exponent %s is negative\n", rhs_str);
405
406 else if (get_unsigned_val(rhs_type, rhs) >=
407 type_bit_width(lhs_type))
408 pr_err("shift exponent %s is too large for %u-bit type %s\n",
409 rhs_str,
410 type_bit_width(lhs_type),
411 lhs_type->type_name);
412 else if (val_is_negative(lhs_type, lhs))
413 pr_err("left shift of negative value %s\n",
414 lhs_str);
415 else
416 pr_err("left shift of %s by %s places cannot be"
417 " represented in type %s\n",
418 lhs_str, rhs_str,
419 lhs_type->type_name);
420
421 ubsan_epilogue(&flags);
422}
423EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
424
425
426void __noreturn
427__ubsan_handle_builtin_unreachable(struct unreachable_data *data)
428{
429 unsigned long flags;
430
431 ubsan_prologue(&data->location, &flags);
432 pr_err("calling __builtin_unreachable()\n");
433 ubsan_epilogue(&flags);
434 panic("can't return from __builtin_unreachable()");
435}
436EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
437
438void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
439 unsigned long val)
440{
441 unsigned long flags;
442 char val_str[VALUE_LENGTH];
443
444 if (suppress_report(&data->location))
445 return;
446
447 ubsan_prologue(&data->location, &flags);
448
449 val_to_string(val_str, sizeof(val_str), data->type, val);
450
451 pr_err("load of value %s is not a valid value for type %s\n",
452 val_str, data->type->type_name);
453
454 ubsan_epilogue(&flags);
455}
456EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
457
