kasan: unset panic_on_warn before calling panic()
[linux-block.git] / lib / ubsan.c
CommitLineData
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
c6d30853 158 current->in_ubsan--;
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159
160 if (panic_on_warn) {
161 /*
162 * This thread may hit another WARN() in the panic path.
163 * Resetting this prevents additional WARN() from panicking the
164 * system on this thread. Other threads are blocked by the
165 * panic_mutex in panic().
166 */
167 panic_on_warn = 0;
168 panic("panic_on_warn set ...\n");
169 }
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170}
171
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172static void handle_overflow(struct overflow_data *data, void *lhs,
173 void *rhs, char op)
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174{
175
176 struct type_descriptor *type = data->type;
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177 char lhs_val_str[VALUE_LENGTH];
178 char rhs_val_str[VALUE_LENGTH];
179
180 if (suppress_report(&data->location))
181 return;
182
ce5c31db 183 ubsan_prologue(&data->location);
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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
ce5c31db 195 ubsan_epilogue();
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196}
197
198void __ubsan_handle_add_overflow(struct overflow_data *data,
f0996bc2 199 void *lhs, void *rhs)
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200{
201
202 handle_overflow(data, lhs, rhs, '+');
203}
204EXPORT_SYMBOL(__ubsan_handle_add_overflow);
205
206void __ubsan_handle_sub_overflow(struct overflow_data *data,
f0996bc2 207 void *lhs, void *rhs)
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208{
209 handle_overflow(data, lhs, rhs, '-');
210}
211EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
212
213void __ubsan_handle_mul_overflow(struct overflow_data *data,
f0996bc2 214 void *lhs, void *rhs)
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215{
216 handle_overflow(data, lhs, rhs, '*');
217}
218EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
219
220void __ubsan_handle_negate_overflow(struct overflow_data *data,
f0996bc2 221 void *old_val)
c6d30853 222{
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223 char old_val_str[VALUE_LENGTH];
224
225 if (suppress_report(&data->location))
226 return;
227
ce5c31db 228 ubsan_prologue(&data->location);
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229
230 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
231
232 pr_err("negation of %s cannot be represented in type %s:\n",
233 old_val_str, data->type->type_name);
234
ce5c31db 235 ubsan_epilogue();
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236}
237EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
238
239
240void __ubsan_handle_divrem_overflow(struct overflow_data *data,
f0996bc2 241 void *lhs, void *rhs)
c6d30853 242{
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243 char rhs_val_str[VALUE_LENGTH];
244
245 if (suppress_report(&data->location))
246 return;
247
ce5c31db 248 ubsan_prologue(&data->location);
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249
250 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
251
252 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
253 pr_err("division of %s by -1 cannot be represented in type %s\n",
254 rhs_val_str, data->type->type_name);
255 else
256 pr_err("division by zero\n");
257
ce5c31db 258 ubsan_epilogue();
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259}
260EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
261
42440c1f 262static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
c6d30853 263{
42440c1f 264 if (suppress_report(data->location))
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265 return;
266
ce5c31db 267 ubsan_prologue(data->location);
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268
269 pr_err("%s null pointer of type %s\n",
270 type_check_kinds[data->type_check_kind],
271 data->type->type_name);
272
ce5c31db 273 ubsan_epilogue();
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274}
275
42440c1f 276static void handle_misaligned_access(struct type_mismatch_data_common *data,
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277 unsigned long ptr)
278{
42440c1f 279 if (suppress_report(data->location))
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280 return;
281
ce5c31db 282 ubsan_prologue(data->location);
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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
ce5c31db 289 ubsan_epilogue();
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290}
291
42440c1f 292static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
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293 unsigned long ptr)
294{
42440c1f 295 if (suppress_report(data->location))
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296 return;
297
ce5c31db 298 ubsan_prologue(data->location);
901d805c 299 pr_err("%s address %p with insufficient space\n",
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300 type_check_kinds[data->type_check_kind],
301 (void *) ptr);
302 pr_err("for an object of type %s\n", data->type->type_name);
ce5c31db 303 ubsan_epilogue();
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304}
305
42440c1f 306static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
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307 unsigned long ptr)
308{
d08965a2 309 unsigned long flags = user_access_save();
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310
311 if (!ptr)
312 handle_null_ptr_deref(data);
313 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
b8fe1120 314 handle_misaligned_access(data, ptr);
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315 else
316 handle_object_size_mismatch(data, ptr);
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317
318 user_access_restore(flags);
c6d30853 319}
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320
321void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
f0996bc2 322 void *ptr)
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323{
324 struct type_mismatch_data_common common_data = {
325 .location = &data->location,
326 .type = data->type,
327 .alignment = data->alignment,
328 .type_check_kind = data->type_check_kind
329 };
330
f0996bc2 331 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
42440c1f 332}
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333EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
334
42440c1f 335void __ubsan_handle_type_mismatch_v1(struct type_mismatch_data_v1 *data,
f0996bc2 336 void *ptr)
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337{
338
339 struct type_mismatch_data_common common_data = {
340 .location = &data->location,
341 .type = data->type,
342 .alignment = 1UL << data->log_alignment,
343 .type_check_kind = data->type_check_kind
344 };
345
f0996bc2 346 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
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347}
348EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
349
f0996bc2 350void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data, void *index)
c6d30853 351{
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352 char index_str[VALUE_LENGTH];
353
354 if (suppress_report(&data->location))
355 return;
356
ce5c31db 357 ubsan_prologue(&data->location);
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358
359 val_to_string(index_str, sizeof(index_str), data->index_type, index);
360 pr_err("index %s is out of range for type %s\n", index_str,
361 data->array_type->type_name);
ce5c31db 362 ubsan_epilogue();
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363}
364EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
365
366void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
f0996bc2 367 void *lhs, void *rhs)
c6d30853 368{
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369 struct type_descriptor *rhs_type = data->rhs_type;
370 struct type_descriptor *lhs_type = data->lhs_type;
371 char rhs_str[VALUE_LENGTH];
372 char lhs_str[VALUE_LENGTH];
9a50dcaf 373 unsigned long ua_flags = user_access_save();
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374
375 if (suppress_report(&data->location))
9a50dcaf 376 goto out;
c6d30853 377
ce5c31db 378 ubsan_prologue(&data->location);
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379
380 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
381 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
382
383 if (val_is_negative(rhs_type, rhs))
384 pr_err("shift exponent %s is negative\n", rhs_str);
385
386 else if (get_unsigned_val(rhs_type, rhs) >=
387 type_bit_width(lhs_type))
388 pr_err("shift exponent %s is too large for %u-bit type %s\n",
389 rhs_str,
390 type_bit_width(lhs_type),
391 lhs_type->type_name);
392 else if (val_is_negative(lhs_type, lhs))
393 pr_err("left shift of negative value %s\n",
394 lhs_str);
395 else
396 pr_err("left shift of %s by %s places cannot be"
397 " represented in type %s\n",
398 lhs_str, rhs_str,
399 lhs_type->type_name);
400
ce5c31db 401 ubsan_epilogue();
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402out:
403 user_access_restore(ua_flags);
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404}
405EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
406
407
1c23b410 408void __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
c6d30853 409{
ce5c31db 410 ubsan_prologue(&data->location);
c6d30853 411 pr_err("calling __builtin_unreachable()\n");
ce5c31db 412 ubsan_epilogue();
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413 panic("can't return from __builtin_unreachable()");
414}
415EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
416
417void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
f0996bc2 418 void *val)
c6d30853 419{
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420 char val_str[VALUE_LENGTH];
421
422 if (suppress_report(&data->location))
423 return;
424
ce5c31db 425 ubsan_prologue(&data->location);
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426
427 val_to_string(val_str, sizeof(val_str), data->type, val);
428
429 pr_err("load of value %s is not a valid value for type %s\n",
430 val_str, data->type->type_name);
431
ce5c31db 432 ubsan_epilogue();
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433}
434EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);