1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * UBSAN error reporting functions
4 *
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 */
8
9 #include <linux/bitops.h>
10 #include <linux/bug.h>
11 #include <linux/ctype.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/types.h>
15 #include <linux/sched.h>
16 #include <linux/uaccess.h>
17
18 #include "ubsan.h"
19
20 const char *type_check_kinds[] = {
21 "load of",
22 "store to",
23 "reference binding to",
24 "member access within",
25 "member call on",
26 "constructor call on",
27 "downcast of",
28 "downcast of"
29 };
30
31 #define REPORTED_BIT 31
32
33 #if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
34 #define COLUMN_MASK (~(1U << REPORTED_BIT))
35 #define LINE_MASK (~0U)
36 #else
37 #define COLUMN_MASK (~0U)
38 #define LINE_MASK (~(1U << REPORTED_BIT))
39 #endif
40
41 #define VALUE_LENGTH 40
42
was_reported(struct source_location * location)43 static bool was_reported(struct source_location *location)
44 {
45 return test_and_set_bit(REPORTED_BIT, &location->reported);
46 }
47
print_source_location(const char * prefix,struct source_location * loc)48 static void print_source_location(const char *prefix,
49 struct source_location *loc)
50 {
51 pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
52 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
53 }
54
suppress_report(struct source_location * loc)55 static bool suppress_report(struct source_location *loc)
56 {
57 return current->in_ubsan || was_reported(loc);
58 }
59
type_is_int(struct type_descriptor * type)60 static bool type_is_int(struct type_descriptor *type)
61 {
62 return type->type_kind == type_kind_int;
63 }
64
type_is_signed(struct type_descriptor * type)65 static bool type_is_signed(struct type_descriptor *type)
66 {
67 WARN_ON(!type_is_int(type));
68 return type->type_info & 1;
69 }
70
type_bit_width(struct type_descriptor * type)71 static unsigned type_bit_width(struct type_descriptor *type)
72 {
73 return 1 << (type->type_info >> 1);
74 }
75
is_inline_int(struct type_descriptor * type)76 static bool is_inline_int(struct type_descriptor *type)
77 {
78 unsigned inline_bits = sizeof(unsigned long)*8;
79 unsigned bits = type_bit_width(type);
80
81 WARN_ON(!type_is_int(type));
82
83 return bits <= inline_bits;
84 }
85
get_signed_val(struct type_descriptor * type,void * val)86 static s_max get_signed_val(struct type_descriptor *type, void *val)
87 {
88 if (is_inline_int(type)) {
89 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
90 unsigned long ulong_val = (unsigned long)val;
91
92 return ((s_max)ulong_val) << extra_bits >> extra_bits;
93 }
94
95 if (type_bit_width(type) == 64)
96 return *(s64 *)val;
97
98 return *(s_max *)val;
99 }
100
val_is_negative(struct type_descriptor * type,void * val)101 static bool val_is_negative(struct type_descriptor *type, void *val)
102 {
103 return type_is_signed(type) && get_signed_val(type, val) < 0;
104 }
105
get_unsigned_val(struct type_descriptor * type,void * val)106 static u_max get_unsigned_val(struct type_descriptor *type, void *val)
107 {
108 if (is_inline_int(type))
109 return (unsigned long)val;
110
111 if (type_bit_width(type) == 64)
112 return *(u64 *)val;
113
114 return *(u_max *)val;
115 }
116
val_to_string(char * str,size_t size,struct type_descriptor * type,void * value)117 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
118 void *value)
119 {
120 if (type_is_int(type)) {
121 if (type_bit_width(type) == 128) {
122 #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
123 u_max val = get_unsigned_val(type, value);
124
125 scnprintf(str, size, "0x%08x%08x%08x%08x",
126 (u32)(val >> 96),
127 (u32)(val >> 64),
128 (u32)(val >> 32),
129 (u32)(val));
130 #else
131 WARN_ON(1);
132 #endif
133 } else if (type_is_signed(type)) {
134 scnprintf(str, size, "%lld",
135 (s64)get_signed_val(type, value));
136 } else {
137 scnprintf(str, size, "%llu",
138 (u64)get_unsigned_val(type, value));
139 }
140 }
141 }
142
143 static DEFINE_SPINLOCK(report_lock);
144
ubsan_prologue(struct source_location * location,unsigned long * flags)145 static void ubsan_prologue(struct source_location *location,
146 unsigned long *flags)
147 {
148 current->in_ubsan++;
149 spin_lock_irqsave(&report_lock, *flags);
150
151 pr_err("========================================"
152 "========================================\n");
153 print_source_location("UBSAN: Undefined behaviour in", location);
154 }
155
ubsan_epilogue(unsigned long * flags)156 static void ubsan_epilogue(unsigned long *flags)
157 {
158 dump_stack();
159 pr_err("========================================"
160 "========================================\n");
161 spin_unlock_irqrestore(&report_lock, *flags);
162 current->in_ubsan--;
163 }
164
handle_overflow(struct overflow_data * data,void * lhs,void * rhs,char op)165 static void handle_overflow(struct overflow_data *data, void *lhs,
166 void *rhs, char op)
167 {
168
169 struct type_descriptor *type = data->type;
170 unsigned long flags;
171 char lhs_val_str[VALUE_LENGTH];
172 char rhs_val_str[VALUE_LENGTH];
173
174 if (suppress_report(&data->location))
175 return;
176
177 ubsan_prologue(&data->location, &flags);
178
179 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
180 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
181 pr_err("%s integer overflow:\n",
182 type_is_signed(type) ? "signed" : "unsigned");
183 pr_err("%s %c %s cannot be represented in type %s\n",
184 lhs_val_str,
185 op,
186 rhs_val_str,
187 type->type_name);
188
189 ubsan_epilogue(&flags);
190 }
191
__ubsan_handle_add_overflow(struct overflow_data * data,void * lhs,void * rhs)192 void __ubsan_handle_add_overflow(struct overflow_data *data,
193 void *lhs, void *rhs)
194 {
195
196 handle_overflow(data, lhs, rhs, '+');
197 }
198 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
199
__ubsan_handle_sub_overflow(struct overflow_data * data,void * lhs,void * rhs)200 void __ubsan_handle_sub_overflow(struct overflow_data *data,
201 void *lhs, void *rhs)
202 {
203 handle_overflow(data, lhs, rhs, '-');
204 }
205 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
206
__ubsan_handle_mul_overflow(struct overflow_data * data,void * lhs,void * rhs)207 void __ubsan_handle_mul_overflow(struct overflow_data *data,
208 void *lhs, void *rhs)
209 {
210 handle_overflow(data, lhs, rhs, '*');
211 }
212 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
213
__ubsan_handle_negate_overflow(struct overflow_data * data,void * old_val)214 void __ubsan_handle_negate_overflow(struct overflow_data *data,
215 void *old_val)
216 {
217 unsigned long flags;
218 char old_val_str[VALUE_LENGTH];
219
220 if (suppress_report(&data->location))
221 return;
222
223 ubsan_prologue(&data->location, &flags);
224
225 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
226
227 pr_err("negation of %s cannot be represented in type %s:\n",
228 old_val_str, data->type->type_name);
229
230 ubsan_epilogue(&flags);
231 }
232 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
233
234
__ubsan_handle_divrem_overflow(struct overflow_data * data,void * lhs,void * rhs)235 void __ubsan_handle_divrem_overflow(struct overflow_data *data,
236 void *lhs, void *rhs)
237 {
238 unsigned long flags;
239 char rhs_val_str[VALUE_LENGTH];
240
241 if (suppress_report(&data->location))
242 return;
243
244 ubsan_prologue(&data->location, &flags);
245
246 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
247
248 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
249 pr_err("division of %s by -1 cannot be represented in type %s\n",
250 rhs_val_str, data->type->type_name);
251 else
252 pr_err("division by zero\n");
253
254 ubsan_epilogue(&flags);
255 }
256 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
257
handle_null_ptr_deref(struct type_mismatch_data_common * data)258 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
259 {
260 unsigned long flags;
261
262 if (suppress_report(data->location))
263 return;
264
265 ubsan_prologue(data->location, &flags);
266
267 pr_err("%s null pointer of type %s\n",
268 type_check_kinds[data->type_check_kind],
269 data->type->type_name);
270
271 ubsan_epilogue(&flags);
272 }
273
handle_misaligned_access(struct type_mismatch_data_common * data,unsigned long ptr)274 static void handle_misaligned_access(struct type_mismatch_data_common *data,
275 unsigned long ptr)
276 {
277 unsigned long flags;
278
279 if (suppress_report(data->location))
280 return;
281
282 ubsan_prologue(data->location, &flags);
283
284 pr_err("%s misaligned address %p for type %s\n",
285 type_check_kinds[data->type_check_kind],
286 (void *)ptr, data->type->type_name);
287 pr_err("which requires %ld byte alignment\n", data->alignment);
288
289 ubsan_epilogue(&flags);
290 }
291
handle_object_size_mismatch(struct type_mismatch_data_common * data,unsigned long ptr)292 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
293 unsigned long ptr)
294 {
295 unsigned long flags;
296
297 if (suppress_report(data->location))
298 return;
299
300 ubsan_prologue(data->location, &flags);
301 pr_err("%s address %p with insufficient space\n",
302 type_check_kinds[data->type_check_kind],
303 (void *) ptr);
304 pr_err("for an object of type %s\n", data->type->type_name);
305 ubsan_epilogue(&flags);
306 }
307
ubsan_type_mismatch_common(struct type_mismatch_data_common * data,unsigned long ptr)308 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
309 unsigned long ptr)
310 {
311 unsigned long flags = user_access_save();
312
313 if (!ptr)
314 handle_null_ptr_deref(data);
315 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
316 handle_misaligned_access(data, ptr);
317 else
318 handle_object_size_mismatch(data, ptr);
319
320 user_access_restore(flags);
321 }
322
__ubsan_handle_type_mismatch(struct type_mismatch_data * data,void * ptr)323 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
324 void *ptr)
325 {
326 struct type_mismatch_data_common common_data = {
327 .location = &data->location,
328 .type = data->type,
329 .alignment = data->alignment,
330 .type_check_kind = data->type_check_kind
331 };
332
333 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
334 }
335 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
336
__ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 * data,void * ptr)337 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
338 void *ptr)
339 {
340
341 struct type_mismatch_data_common common_data = {
342 .location = &data->location,
343 .type = data->type,
344 .alignment = 1UL << data->log_alignment,
345 .type_check_kind = data->type_check_kind
346 };
347
348 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
349 }
350 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
351
__ubsan_handle_out_of_bounds(struct out_of_bounds_data * data,void * index)352 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index)
353 {
354 unsigned long flags;
355 char index_str[VALUE_LENGTH];
356
357 if (suppress_report(&data->location))
358 return;
359
360 ubsan_prologue(&data->location, &flags);
361
362 val_to_string(index_str, sizeof(index_str), data->index_type, index);
363 pr_err("index %s is out of range for type %s\n", index_str,
364 data->array_type->type_name);
365 ubsan_epilogue(&flags);
366 }
367 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
368
__ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data * data,void * lhs,void * rhs)369 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
370 void *lhs, void *rhs)
371 {
372 unsigned long flags;
373 struct type_descriptor *rhs_type = data->rhs_type;
374 struct type_descriptor *lhs_type = data->lhs_type;
375 char rhs_str[VALUE_LENGTH];
376 char lhs_str[VALUE_LENGTH];
377
378 if (suppress_report(&data->location))
379 return;
380
381 ubsan_prologue(&data->location, &flags);
382
383 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
384 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
385
386 if (val_is_negative(rhs_type, rhs))
387 pr_err("shift exponent %s is negative\n", rhs_str);
388
389 else if (get_unsigned_val(rhs_type, rhs) >=
390 type_bit_width(lhs_type))
391 pr_err("shift exponent %s is too large for %u-bit type %s\n",
392 rhs_str,
393 type_bit_width(lhs_type),
394 lhs_type->type_name);
395 else if (val_is_negative(lhs_type, lhs))
396 pr_err("left shift of negative value %s\n",
397 lhs_str);
398 else
399 pr_err("left shift of %s by %s places cannot be"
400 " represented in type %s\n",
401 lhs_str, rhs_str,
402 lhs_type->type_name);
403
404 ubsan_epilogue(&flags);
405 }
406 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
407
408
__ubsan_handle_builtin_unreachable(struct unreachable_data * data)409 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
410 {
411 unsigned long flags;
412
413 ubsan_prologue(&data->location, &flags);
414 pr_err("calling __builtin_unreachable()\n");
415 ubsan_epilogue(&flags);
416 panic("can't return from __builtin_unreachable()");
417 }
418 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
419
__ubsan_handle_load_invalid_value(struct invalid_value_data * data,void * val)420 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
421 void *val)
422 {
423 unsigned long flags;
424 char val_str[VALUE_LENGTH];
425
426 if (suppress_report(&data->location))
427 return;
428
429 ubsan_prologue(&data->location, &flags);
430
431 val_to_string(val_str, sizeof(val_str), data->type, val);
432
433 pr_err("load of value %s is not a valid value for type %s\n",
434 val_str, data->type->type_name);
435
436 ubsan_epilogue(&flags);
437 }
438 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
439
