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
ubsan_prologue(struct source_location * location)143 static void ubsan_prologue(struct source_location *location)
144 {
145 current->in_ubsan++;
146
147 pr_err("========================================"
148 "========================================\n");
149 print_source_location("UBSAN: Undefined behaviour in", location);
150 }
151
ubsan_epilogue(void)152 static void ubsan_epilogue(void)
153 {
154 dump_stack();
155 pr_err("========================================"
156 "========================================\n");
157
158 current->in_ubsan--;
159 }
160
handle_overflow(struct overflow_data * data,void * lhs,void * rhs,char op)161 static void handle_overflow(struct overflow_data *data, void *lhs,
162 void *rhs, char op)
163 {
164
165 struct type_descriptor *type = data->type;
166 char lhs_val_str[VALUE_LENGTH];
167 char rhs_val_str[VALUE_LENGTH];
168
169 if (suppress_report(&data->location))
170 return;
171
172 ubsan_prologue(&data->location);
173
174 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
175 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
176 pr_err("%s integer overflow:\n",
177 type_is_signed(type) ? "signed" : "unsigned");
178 pr_err("%s %c %s cannot be represented in type %s\n",
179 lhs_val_str,
180 op,
181 rhs_val_str,
182 type->type_name);
183
184 ubsan_epilogue();
185 }
186
__ubsan_handle_add_overflow(struct overflow_data * data,void * lhs,void * rhs)187 void __ubsan_handle_add_overflow(struct overflow_data *data,
188 void *lhs, void *rhs)
189 {
190
191 handle_overflow(data, lhs, rhs, '+');
192 }
193 EXPORT_SYMBOL(__ubsan_handle_add_overflow);
194
__ubsan_handle_sub_overflow(struct overflow_data * data,void * lhs,void * rhs)195 void __ubsan_handle_sub_overflow(struct overflow_data *data,
196 void *lhs, void *rhs)
197 {
198 handle_overflow(data, lhs, rhs, '-');
199 }
200 EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
201
__ubsan_handle_mul_overflow(struct overflow_data * data,void * lhs,void * rhs)202 void __ubsan_handle_mul_overflow(struct overflow_data *data,
203 void *lhs, void *rhs)
204 {
205 handle_overflow(data, lhs, rhs, '*');
206 }
207 EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
208
__ubsan_handle_negate_overflow(struct overflow_data * data,void * old_val)209 void __ubsan_handle_negate_overflow(struct overflow_data *data,
210 void *old_val)
211 {
212 char old_val_str[VALUE_LENGTH];
213
214 if (suppress_report(&data->location))
215 return;
216
217 ubsan_prologue(&data->location);
218
219 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
220
221 pr_err("negation of %s cannot be represented in type %s:\n",
222 old_val_str, data->type->type_name);
223
224 ubsan_epilogue();
225 }
226 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
227
228
__ubsan_handle_divrem_overflow(struct overflow_data * data,void * lhs,void * rhs)229 void __ubsan_handle_divrem_overflow(struct overflow_data *data,
230 void *lhs, void *rhs)
231 {
232 char rhs_val_str[VALUE_LENGTH];
233
234 if (suppress_report(&data->location))
235 return;
236
237 ubsan_prologue(&data->location);
238
239 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
240
241 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
242 pr_err("division of %s by -1 cannot be represented in type %s\n",
243 rhs_val_str, data->type->type_name);
244 else
245 pr_err("division by zero\n");
246
247 ubsan_epilogue();
248 }
249 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
250
handle_null_ptr_deref(struct type_mismatch_data_common * data)251 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
252 {
253 if (suppress_report(data->location))
254 return;
255
256 ubsan_prologue(data->location);
257
258 pr_err("%s null pointer of type %s\n",
259 type_check_kinds[data->type_check_kind],
260 data->type->type_name);
261
262 ubsan_epilogue();
263 }
264
handle_misaligned_access(struct type_mismatch_data_common * data,unsigned long ptr)265 static void handle_misaligned_access(struct type_mismatch_data_common *data,
266 unsigned long ptr)
267 {
268 if (suppress_report(data->location))
269 return;
270
271 ubsan_prologue(data->location);
272
273 pr_err("%s misaligned address %p for type %s\n",
274 type_check_kinds[data->type_check_kind],
275 (void *)ptr, data->type->type_name);
276 pr_err("which requires %ld byte alignment\n", data->alignment);
277
278 ubsan_epilogue();
279 }
280
handle_object_size_mismatch(struct type_mismatch_data_common * data,unsigned long ptr)281 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
282 unsigned long ptr)
283 {
284 if (suppress_report(data->location))
285 return;
286
287 ubsan_prologue(data->location);
288 pr_err("%s address %p with insufficient space\n",
289 type_check_kinds[data->type_check_kind],
290 (void *) ptr);
291 pr_err("for an object of type %s\n", data->type->type_name);
292 ubsan_epilogue();
293 }
294
ubsan_type_mismatch_common(struct type_mismatch_data_common * data,unsigned long ptr)295 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
296 unsigned long ptr)
297 {
298 unsigned long flags = user_access_save();
299
300 if (!ptr)
301 handle_null_ptr_deref(data);
302 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
303 handle_misaligned_access(data, ptr);
304 else
305 handle_object_size_mismatch(data, ptr);
306
307 user_access_restore(flags);
308 }
309
__ubsan_handle_type_mismatch(struct type_mismatch_data * data,void * ptr)310 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
311 void *ptr)
312 {
313 struct type_mismatch_data_common common_data = {
314 .location = &data->location,
315 .type = data->type,
316 .alignment = data->alignment,
317 .type_check_kind = data->type_check_kind
318 };
319
320 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
321 }
322 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
323
__ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 * data,void * ptr)324 void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
325 void *ptr)
326 {
327
328 struct type_mismatch_data_common common_data = {
329 .location = &data->location,
330 .type = data->type,
331 .alignment = 1UL << data->log_alignment,
332 .type_check_kind = data->type_check_kind
333 };
334
335 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
336 }
337 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
338
__ubsan_handle_out_of_bounds(struct out_of_bounds_data * data,void * index)339 void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index)
340 {
341 char index_str[VALUE_LENGTH];
342
343 if (suppress_report(&data->location))
344 return;
345
346 ubsan_prologue(&data->location);
347
348 val_to_string(index_str, sizeof(index_str), data->index_type, index);
349 pr_err("index %s is out of range for type %s\n", index_str,
350 data->array_type->type_name);
351 ubsan_epilogue();
352 }
353 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
354
__ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data * data,void * lhs,void * rhs)355 void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
356 void *lhs, void *rhs)
357 {
358 struct type_descriptor *rhs_type = data->rhs_type;
359 struct type_descriptor *lhs_type = data->lhs_type;
360 char rhs_str[VALUE_LENGTH];
361 char lhs_str[VALUE_LENGTH];
362 unsigned long ua_flags = user_access_save();
363
364 if (suppress_report(&data->location))
365 goto out;
366
367 ubsan_prologue(&data->location);
368
369 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
370 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
371
372 if (val_is_negative(rhs_type, rhs))
373 pr_err("shift exponent %s is negative\n", rhs_str);
374
375 else if (get_unsigned_val(rhs_type, rhs) >=
376 type_bit_width(lhs_type))
377 pr_err("shift exponent %s is too large for %u-bit type %s\n",
378 rhs_str,
379 type_bit_width(lhs_type),
380 lhs_type->type_name);
381 else if (val_is_negative(lhs_type, lhs))
382 pr_err("left shift of negative value %s\n",
383 lhs_str);
384 else
385 pr_err("left shift of %s by %s places cannot be"
386 " represented in type %s\n",
387 lhs_str, rhs_str,
388 lhs_type->type_name);
389
390 ubsan_epilogue();
391 out:
392 user_access_restore(ua_flags);
393 }
394 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
395
396
__ubsan_handle_builtin_unreachable(struct unreachable_data * data)397 void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
398 {
399 ubsan_prologue(&data->location);
400 pr_err("calling __builtin_unreachable()\n");
401 ubsan_epilogue();
402 panic("can't return from __builtin_unreachable()");
403 }
404 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
405
__ubsan_handle_load_invalid_value(struct invalid_value_data * data,void * val)406 void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
407 void *val)
408 {
409 char val_str[VALUE_LENGTH];
410
411 if (suppress_report(&data->location))
412 return;
413
414 ubsan_prologue(&data->location);
415
416 val_to_string(val_str, sizeof(val_str), data->type, val);
417
418 pr_err("load of value %s is not a valid value for type %s\n",
419 val_str, data->type->type_name);
420
421 ubsan_epilogue();
422 }
423 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
424