1/*
2 * UBSAN error reporting functions
3 *
4 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
5 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 */
12
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 DEFINE_SPINLOCK(report_lock);
145
146static void ubsan_prologue(struct source_location *location,
147 unsigned long *flags)
148{
149 current->in_ubsan++;
150 spin_lock_irqsave(&report_lock, *flags);
151
152 pr_err("========================================"
153 "========================================\n");
154 print_source_location("UBSAN: Undefined behaviour in", location);
155}
156
157static void ubsan_epilogue(unsigned long *flags)
158{
159 dump_stack();
160 pr_err("========================================"
161 "========================================\n");
162 spin_unlock_irqrestore(&report_lock, *flags);
163 current->in_ubsan--;
164}
165
166static void handle_overflow(struct overflow_data *data, unsigned long lhs,
167 unsigned long rhs, char op)
168{
169
170 struct type_descriptor *type = data->type;
171 unsigned long flags;
172 char lhs_val_str[VALUE_LENGTH];
173 char rhs_val_str[VALUE_LENGTH];
174
175 if (suppress_report(&data->location))
176 return;
177
178 ubsan_prologue(&data->location, &flags);
179
180 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
181 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
182 pr_err("%s integer overflow:\n",
183 type_is_signed(type) ? "signed" : "unsigned");
184 pr_err("%s %c %s cannot be represented in type %s\n",
185 lhs_val_str,
186 op,
187 rhs_val_str,
188 type->type_name);
189
190 ubsan_epilogue(&flags);
191}
192
193void __ubsan_handle_add_overflow(struct overflow_data *data,
194 unsigned long lhs,
195 unsigned long rhs)
196{
197
198 handle_overflow(data, lhs, rhs, '+');
199}
200EXPORT_SYMBOL(__ubsan_handle_add_overflow);
201
202void __ubsan_handle_sub_overflow(struct overflow_data *data,
203 unsigned long lhs,
204 unsigned long rhs)
205{
206 handle_overflow(data, lhs, rhs, '-');
207}
208EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
209
210void __ubsan_handle_mul_overflow(struct overflow_data *data,
211 unsigned long lhs,
212 unsigned long rhs)
213{
214 handle_overflow(data, lhs, rhs, '*');
215}
216EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
217
218void __ubsan_handle_negate_overflow(struct overflow_data *data,
219 unsigned long old_val)
220{
221 unsigned long flags;
222 char old_val_str[VALUE_LENGTH];
223
224 if (suppress_report(&data->location))
225 return;
226
227 ubsan_prologue(&data->location, &flags);
228
229 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
230
231 pr_err("negation of %s cannot be represented in type %s:\n",
232 old_val_str, data->type->type_name);
233
234 ubsan_epilogue(&flags);
235}
236EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
237
238
239void __ubsan_handle_divrem_overflow(struct overflow_data *data,
240 unsigned long lhs,
241 unsigned long rhs)
242{
243 unsigned long flags;
244 char rhs_val_str[VALUE_LENGTH];
245
246 if (suppress_report(&data->location))
247 return;
248
249 ubsan_prologue(&data->location, &flags);
250
251 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
252
253 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
254 pr_err("division of %s by -1 cannot be represented in type %s\n",
255 rhs_val_str, data->type->type_name);
256 else
257 pr_err("division by zero\n");
258
259 ubsan_epilogue(&flags);
260}
261EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
262
263static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
264{
265 unsigned long flags;
266
267 if (suppress_report(data->location))
268 return;
269
270 ubsan_prologue(data->location, &flags);
271
272 pr_err("%s null pointer of type %s\n",
273 type_check_kinds[data->type_check_kind],
274 data->type->type_name);
275
276 ubsan_epilogue(&flags);
277}
278
279static void handle_misaligned_access(struct type_mismatch_data_common *data,
280 unsigned long ptr)
281{
282 unsigned long flags;
283
284 if (suppress_report(data->location))
285 return;
286
287 ubsan_prologue(data->location, &flags);
288
289 pr_err("%s misaligned address %p for type %s\n",
290 type_check_kinds[data->type_check_kind],
291 (void *)ptr, data->type->type_name);
292 pr_err("which requires %ld byte alignment\n", data->alignment);
293
294 ubsan_epilogue(&flags);
295}
296
297static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
298 unsigned long ptr)
299{
300 unsigned long flags;
301
302 if (suppress_report(data->location))
303 return;
304
305 ubsan_prologue(data->location, &flags);
306 pr_err("%s address %p with insufficient space\n",
307 type_check_kinds[data->type_check_kind],
308 (void *) ptr);
309 pr_err("for an object of type %s\n", data->type->type_name);
310 ubsan_epilogue(&flags);
311}
312
313static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
314 unsigned long ptr)
315{
316
317 if (!ptr)
318 handle_null_ptr_deref(data);
319 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
320 handle_misaligned_access(data, ptr);
321 else
322 handle_object_size_mismatch(data, ptr);
323}
324
325void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
326 unsigned long ptr)
327{
328 struct type_mismatch_data_common common_data = {
329 .location = &data->location,
330 .type = data->type,
331 .alignment = data->alignment,
332 .type_check_kind = data->type_check_kind
333 };
334
335 ubsan_type_mismatch_common(&common_data, ptr);
336}
337EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
338
339void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
340 unsigned long ptr)
341{
342
343 struct type_mismatch_data_common common_data = {
344 .location = &data->location,
345 .type = data->type,
346 .alignment = 1UL << data->log_alignment,
347 .type_check_kind = data->type_check_kind
348 };
349
350 ubsan_type_mismatch_common(&common_data, ptr);
351}
352EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
353
354void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data,
355 unsigned long bound)
356{
357 unsigned long flags;
358 char bound_str[VALUE_LENGTH];
359
360 if (suppress_report(&data->location))
361 return;
362
363 ubsan_prologue(&data->location, &flags);
364
365 val_to_string(bound_str, sizeof(bound_str), data->type, bound);
366 pr_err("variable length array bound value %s <= 0\n", bound_str);
367
368 ubsan_epilogue(&flags);
369}
370EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive);
371
372void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data,
373 unsigned long index)
374{
375 unsigned long flags;
376 char index_str[VALUE_LENGTH];
377
378 if (suppress_report(&data->location))
379 return;
380
381 ubsan_prologue(&data->location, &flags);
382
383 val_to_string(index_str, sizeof(index_str), data->index_type, index);
384 pr_err("index %s is out of range for type %s\n", index_str,
385 data->array_type->type_name);
386 ubsan_epilogue(&flags);
387}
388EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
389
390void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
391 unsigned long lhs, unsigned long rhs)
392{
393 unsigned long flags;
394 struct type_descriptor *rhs_type = data->rhs_type;
395 struct type_descriptor *lhs_type = data->lhs_type;
396 char rhs_str[VALUE_LENGTH];
397 char lhs_str[VALUE_LENGTH];
398
399 if (suppress_report(&data->location))
400 return;
401
402 ubsan_prologue(&data->location, &flags);
403
404 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
405 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
406
407 if (val_is_negative(rhs_type, rhs))
408 pr_err("shift exponent %s is negative\n", rhs_str);
409
410 else if (get_unsigned_val(rhs_type, rhs) >=
411 type_bit_width(lhs_type))
412 pr_err("shift exponent %s is too large for %u-bit type %s\n",
413 rhs_str,
414 type_bit_width(lhs_type),
415 lhs_type->type_name);
416 else if (val_is_negative(lhs_type, lhs))
417 pr_err("left shift of negative value %s\n",
418 lhs_str);
419 else
420 pr_err("left shift of %s by %s places cannot be"
421 " represented in type %s\n",
422 lhs_str, rhs_str,
423 lhs_type->type_name);
424
425 ubsan_epilogue(&flags);
426}
427EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
428
429
430void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
431{
432 unsigned long flags;
433
434 ubsan_prologue(&data->location, &flags);
435 pr_err("calling __builtin_unreachable()\n");
436 ubsan_epilogue(&flags);
437 panic("can't return from __builtin_unreachable()");
438}
439EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
440
441void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
442 unsigned long val)
443{
444 unsigned long flags;
445 char val_str[VALUE_LENGTH];
446
447 if (suppress_report(&data->location))
448 return;
449
450 ubsan_prologue(&data->location, &flags);
451
452 val_to_string(val_str, sizeof(val_str), data->type, val);
453
454 pr_err("load of value %s is not a valid value for type %s\n",
455 val_str, data->type->type_name);
456
457 ubsan_epilogue(&flags);
458}
459EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
460