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d2912cb1 1// SPDX-License-Identifier: GPL-2.0-only
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2/*
3 * UBSAN error reporting functions
4 *
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
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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>
d08965a2 16#include <linux/uaccess.h>
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17
18#include "ubsan.h"
19
20const 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
43static bool was_reported(struct source_location *location)
44{
45 return test_and_set_bit(REPORTED_BIT, &location->reported);
46}
47
48static 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
55static bool suppress_report(struct source_location *loc)
56{
57 return current->in_ubsan || was_reported(loc);
58}
59
60static bool type_is_int(struct type_descriptor *type)
61{
62 return type->type_kind == type_kind_int;
63}
64
65static bool type_is_signed(struct type_descriptor *type)
66{
67 WARN_ON(!type_is_int(type));
68 return type->type_info & 1;
69}
70
71static unsigned type_bit_width(struct type_descriptor *type)
72{
73 return 1 << (type->type_info >> 1);
74}
75
76static 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
f0996bc2 86static s_max get_signed_val(struct type_descriptor *type, void *val)
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87{
88 if (is_inline_int(type)) {
89 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
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90 unsigned long ulong_val = (unsigned long)val;
91
92 return ((s_max)ulong_val) << extra_bits >> extra_bits;
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93 }
94
95 if (type_bit_width(type) == 64)
96 return *(s64 *)val;
97
98 return *(s_max *)val;
99}
100
f0996bc2 101static bool val_is_negative(struct type_descriptor *type, void *val)
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102{
103 return type_is_signed(type) && get_signed_val(type, val) < 0;
104}
105
f0996bc2 106static u_max get_unsigned_val(struct type_descriptor *type, void *val)
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107{
108 if (is_inline_int(type))
f0996bc2 109 return (unsigned long)val;
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110
111 if (type_bit_width(type) == 64)
112 return *(u64 *)val;
113
114 return *(u_max *)val;
115}
116
117static void val_to_string(char *str, size_t size, struct type_descriptor *type,
f0996bc2 118 void *value)
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119{
120 if (type_is_int(type)) {
121 if (type_bit_width(type) == 128) {
c12d3362 122#if defined(CONFIG_ARCH_SUPPORTS_INT128)
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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
ce5c31db 143static void ubsan_prologue(struct source_location *location)
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144{
145 current->in_ubsan++;
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146
147 pr_err("========================================"
148 "========================================\n");
149 print_source_location("UBSAN: Undefined behaviour in", location);
150}
151
ce5c31db 152static void ubsan_epilogue(void)
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153{
154 dump_stack();
155 pr_err("========================================"
156 "========================================\n");
ce5c31db 157
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158 current->in_ubsan--;
159}
160
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161static void handle_overflow(struct overflow_data *data, void *lhs,
162 void *rhs, char op)
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163{
164
165 struct type_descriptor *type = data->type;
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166 char lhs_val_str[VALUE_LENGTH];
167 char rhs_val_str[VALUE_LENGTH];
168
169 if (suppress_report(&data->location))
170 return;
171
ce5c31db 172 ubsan_prologue(&data->location);
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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
ce5c31db 184 ubsan_epilogue();
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185}
186
187void __ubsan_handle_add_overflow(struct overflow_data *data,
f0996bc2 188 void *lhs, void *rhs)
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189{
190
191 handle_overflow(data, lhs, rhs, '+');
192}
193EXPORT_SYMBOL(__ubsan_handle_add_overflow);
194
195void __ubsan_handle_sub_overflow(struct overflow_data *data,
f0996bc2 196 void *lhs, void *rhs)
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197{
198 handle_overflow(data, lhs, rhs, '-');
199}
200EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
201
202void __ubsan_handle_mul_overflow(struct overflow_data *data,
f0996bc2 203 void *lhs, void *rhs)
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204{
205 handle_overflow(data, lhs, rhs, '*');
206}
207EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
208
209void __ubsan_handle_negate_overflow(struct overflow_data *data,
f0996bc2 210 void *old_val)
c6d30853 211{
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212 char old_val_str[VALUE_LENGTH];
213
214 if (suppress_report(&data->location))
215 return;
216
ce5c31db 217 ubsan_prologue(&data->location);
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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
ce5c31db 224 ubsan_epilogue();
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225}
226EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
227
228
229void __ubsan_handle_divrem_overflow(struct overflow_data *data,
f0996bc2 230 void *lhs, void *rhs)
c6d30853 231{
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232 char rhs_val_str[VALUE_LENGTH];
233
234 if (suppress_report(&data->location))
235 return;
236
ce5c31db 237 ubsan_prologue(&data->location);
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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
ce5c31db 247 ubsan_epilogue();
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248}
249EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
250
42440c1f 251static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
c6d30853 252{
42440c1f 253 if (suppress_report(data->location))
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254 return;
255
ce5c31db 256 ubsan_prologue(data->location);
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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
ce5c31db 262 ubsan_epilogue();
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263}
264
42440c1f 265static void handle_misaligned_access(struct type_mismatch_data_common *data,
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266 unsigned long ptr)
267{
42440c1f 268 if (suppress_report(data->location))
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269 return;
270
ce5c31db 271 ubsan_prologue(data->location);
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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
ce5c31db 278 ubsan_epilogue();
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279}
280
42440c1f 281static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
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282 unsigned long ptr)
283{
42440c1f 284 if (suppress_report(data->location))
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285 return;
286
ce5c31db 287 ubsan_prologue(data->location);
901d805c 288 pr_err("%s address %p with insufficient space\n",
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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);
ce5c31db 292 ubsan_epilogue();
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293}
294
42440c1f 295static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
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296 unsigned long ptr)
297{
d08965a2 298 unsigned long flags = user_access_save();
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299
300 if (!ptr)
301 handle_null_ptr_deref(data);
302 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
b8fe1120 303 handle_misaligned_access(data, ptr);
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304 else
305 handle_object_size_mismatch(data, ptr);
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306
307 user_access_restore(flags);
c6d30853 308}
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309
310void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
f0996bc2 311 void *ptr)
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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
f0996bc2 320 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
42440c1f 321}
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322EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
323
42440c1f 324void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
f0996bc2 325 void *ptr)
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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
f0996bc2 335 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
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336}
337EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
338
f0996bc2 339void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index)
c6d30853 340{
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341 char index_str[VALUE_LENGTH];
342
343 if (suppress_report(&data->location))
344 return;
345
ce5c31db 346 ubsan_prologue(&data->location);
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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);
ce5c31db 351 ubsan_epilogue();
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352}
353EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
354
355void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
f0996bc2 356 void *lhs, void *rhs)
c6d30853 357{
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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];
9a50dcaf 362 unsigned long ua_flags = user_access_save();
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363
364 if (suppress_report(&data->location))
9a50dcaf 365 goto out;
c6d30853 366
ce5c31db 367 ubsan_prologue(&data->location);
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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
ce5c31db 390 ubsan_epilogue();
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391out:
392 user_access_restore(ua_flags);
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393}
394EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
395
396
1c23b410 397void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
c6d30853 398{
ce5c31db 399 ubsan_prologue(&data->location);
c6d30853 400 pr_err("calling __builtin_unreachable()\n");
ce5c31db 401 ubsan_epilogue();
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402 panic("can't return from __builtin_unreachable()");
403}
404EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
405
406void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
f0996bc2 407 void *val)
c6d30853 408{
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409 char val_str[VALUE_LENGTH];
410
411 if (suppress_report(&data->location))
412 return;
413
ce5c31db 414 ubsan_prologue(&data->location);
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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
ce5c31db 421 ubsan_epilogue();
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422}
423EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);