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
suppress_report(struct source_location * loc)48 static bool suppress_report(struct source_location *loc)
49 {
50 return current->in_ubsan || was_reported(loc);
51 }
52
type_is_int(struct type_descriptor * type)53 static bool type_is_int(struct type_descriptor *type)
54 {
55 return type->type_kind == type_kind_int;
56 }
57
type_is_signed(struct type_descriptor * type)58 static bool type_is_signed(struct type_descriptor *type)
59 {
60 WARN_ON(!type_is_int(type));
61 return type->type_info & 1;
62 }
63
type_bit_width(struct type_descriptor * type)64 static unsigned type_bit_width(struct type_descriptor *type)
65 {
66 return 1 << (type->type_info >> 1);
67 }
68
is_inline_int(struct type_descriptor * type)69 static bool is_inline_int(struct type_descriptor *type)
70 {
71 unsigned inline_bits = sizeof(unsigned long)*8;
72 unsigned bits = type_bit_width(type);
73
74 WARN_ON(!type_is_int(type));
75
76 return bits <= inline_bits;
77 }
78
get_signed_val(struct type_descriptor * type,void * val)79 static s_max get_signed_val(struct type_descriptor *type, void *val)
80 {
81 if (is_inline_int(type)) {
82 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
83 unsigned long ulong_val = (unsigned long)val;
84
85 return ((s_max)ulong_val) << extra_bits >> extra_bits;
86 }
87
88 if (type_bit_width(type) == 64)
89 return *(s64 *)val;
90
91 return *(s_max *)val;
92 }
93
val_is_negative(struct type_descriptor * type,void * val)94 static bool val_is_negative(struct type_descriptor *type, void *val)
95 {
96 return type_is_signed(type) && get_signed_val(type, val) < 0;
97 }
98
get_unsigned_val(struct type_descriptor * type,void * val)99 static u_max get_unsigned_val(struct type_descriptor *type, void *val)
100 {
101 if (is_inline_int(type))
102 return (unsigned long)val;
103
104 if (type_bit_width(type) == 64)
105 return *(u64 *)val;
106
107 return *(u_max *)val;
108 }
109
val_to_string(char * str,size_t size,struct type_descriptor * type,void * value)110 static void val_to_string(char *str, size_t size, struct type_descriptor *type,
111 void *value)
112 {
113 if (type_is_int(type)) {
114 if (type_bit_width(type) == 128) {
115 #if defined(CONFIG_ARCH_SUPPORTS_INT128)
116 u_max val = get_unsigned_val(type, value);
117
118 scnprintf(str, size, "0x%08x%08x%08x%08x",
119 (u32)(val >> 96),
120 (u32)(val >> 64),
121 (u32)(val >> 32),
122 (u32)(val));
123 #else
124 WARN_ON(1);
125 #endif
126 } else if (type_is_signed(type)) {
127 scnprintf(str, size, "%lld",
128 (s64)get_signed_val(type, value));
129 } else {
130 scnprintf(str, size, "%llu",
131 (u64)get_unsigned_val(type, value));
132 }
133 }
134 }
135
ubsan_prologue(struct source_location * loc,const char * reason)136 static void ubsan_prologue(struct source_location *loc, const char *reason)
137 {
138 current->in_ubsan++;
139
140 pr_err("========================================"
141 "========================================\n");
142 pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
143 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
144 }
145
ubsan_epilogue(void)146 static void ubsan_epilogue(void)
147 {
148 dump_stack();
149 pr_err("========================================"
150 "========================================\n");
151
152 current->in_ubsan--;
153
154 if (panic_on_warn) {
155 /*
156 * This thread may hit another WARN() in the panic path.
157 * Resetting this prevents additional WARN() from panicking the
158 * system on this thread. Other threads are blocked by the
159 * panic_mutex in panic().
160 */
161 panic_on_warn = 0;
162 panic("panic_on_warn set ...\n");
163 }
164 }
165
handle_overflow(struct overflow_data * data,void * lhs,void * rhs,char op)166 static void handle_overflow(struct overflow_data *data, void *lhs,
167 void *rhs, char op)
168 {
169
170 struct type_descriptor *type = data->type;
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, type_is_signed(type) ?
178 "signed-integer-overflow" :
179 "unsigned-integer-overflow");
180
181 val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
182 val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
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();
190 }
191
__ubsan_handle_add_overflow(void * data,void * lhs,void * rhs)192 void __ubsan_handle_add_overflow(void *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(void * data,void * lhs,void * rhs)200 void __ubsan_handle_sub_overflow(void *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(void * data,void * lhs,void * rhs)207 void __ubsan_handle_mul_overflow(void *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(void * _data,void * old_val)214 void __ubsan_handle_negate_overflow(void *_data, void *old_val)
215 {
216 struct overflow_data *data = _data;
217 char old_val_str[VALUE_LENGTH];
218
219 if (suppress_report(&data->location))
220 return;
221
222 ubsan_prologue(&data->location, "negation-overflow");
223
224 val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
225
226 pr_err("negation of %s cannot be represented in type %s:\n",
227 old_val_str, data->type->type_name);
228
229 ubsan_epilogue();
230 }
231 EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
232
233
__ubsan_handle_divrem_overflow(void * _data,void * lhs,void * rhs)234 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
235 {
236 struct overflow_data *data = _data;
237 char rhs_val_str[VALUE_LENGTH];
238
239 if (suppress_report(&data->location))
240 return;
241
242 ubsan_prologue(&data->location, "division-overflow");
243
244 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
245
246 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
247 pr_err("division of %s by -1 cannot be represented in type %s\n",
248 rhs_val_str, data->type->type_name);
249 else
250 pr_err("division by zero\n");
251
252 ubsan_epilogue();
253 }
254 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
255
handle_null_ptr_deref(struct type_mismatch_data_common * data)256 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
257 {
258 if (suppress_report(data->location))
259 return;
260
261 ubsan_prologue(data->location, "null-ptr-deref");
262
263 pr_err("%s null pointer of type %s\n",
264 type_check_kinds[data->type_check_kind],
265 data->type->type_name);
266
267 ubsan_epilogue();
268 }
269
handle_misaligned_access(struct type_mismatch_data_common * data,unsigned long ptr)270 static void handle_misaligned_access(struct type_mismatch_data_common *data,
271 unsigned long ptr)
272 {
273 if (suppress_report(data->location))
274 return;
275
276 ubsan_prologue(data->location, "misaligned-access");
277
278 pr_err("%s misaligned address %p for type %s\n",
279 type_check_kinds[data->type_check_kind],
280 (void *)ptr, data->type->type_name);
281 pr_err("which requires %ld byte alignment\n", data->alignment);
282
283 ubsan_epilogue();
284 }
285
handle_object_size_mismatch(struct type_mismatch_data_common * data,unsigned long ptr)286 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
287 unsigned long ptr)
288 {
289 if (suppress_report(data->location))
290 return;
291
292 ubsan_prologue(data->location, "object-size-mismatch");
293 pr_err("%s address %p with insufficient space\n",
294 type_check_kinds[data->type_check_kind],
295 (void *) ptr);
296 pr_err("for an object of type %s\n", data->type->type_name);
297 ubsan_epilogue();
298 }
299
ubsan_type_mismatch_common(struct type_mismatch_data_common * data,unsigned long ptr)300 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
301 unsigned long ptr)
302 {
303 unsigned long flags = user_access_save();
304
305 if (!ptr)
306 handle_null_ptr_deref(data);
307 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
308 handle_misaligned_access(data, ptr);
309 else
310 handle_object_size_mismatch(data, ptr);
311
312 user_access_restore(flags);
313 }
314
__ubsan_handle_type_mismatch(struct type_mismatch_data * data,void * ptr)315 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
316 void *ptr)
317 {
318 struct type_mismatch_data_common common_data = {
319 .location = &data->location,
320 .type = data->type,
321 .alignment = data->alignment,
322 .type_check_kind = data->type_check_kind
323 };
324
325 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
326 }
327 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
328
__ubsan_handle_type_mismatch_v1(void * _data,void * ptr)329 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
330 {
331 struct type_mismatch_data_v1 *data = _data;
332 struct type_mismatch_data_common common_data = {
333 .location = &data->location,
334 .type = data->type,
335 .alignment = 1UL << data->log_alignment,
336 .type_check_kind = data->type_check_kind
337 };
338
339 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
340 }
341 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
342
__ubsan_handle_out_of_bounds(void * _data,void * index)343 void __ubsan_handle_out_of_bounds(void *_data, void *index)
344 {
345 struct out_of_bounds_data *data = _data;
346 char index_str[VALUE_LENGTH];
347
348 if (suppress_report(&data->location))
349 return;
350
351 ubsan_prologue(&data->location, "array-index-out-of-bounds");
352
353 val_to_string(index_str, sizeof(index_str), data->index_type, index);
354 pr_err("index %s is out of range for type %s\n", index_str,
355 data->array_type->type_name);
356 ubsan_epilogue();
357 }
358 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
359
__ubsan_handle_shift_out_of_bounds(void * _data,void * lhs,void * rhs)360 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
361 {
362 struct shift_out_of_bounds_data *data = _data;
363 struct type_descriptor *rhs_type = data->rhs_type;
364 struct type_descriptor *lhs_type = data->lhs_type;
365 char rhs_str[VALUE_LENGTH];
366 char lhs_str[VALUE_LENGTH];
367 unsigned long ua_flags = user_access_save();
368
369 if (suppress_report(&data->location))
370 goto out;
371
372 ubsan_prologue(&data->location, "shift-out-of-bounds");
373
374 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
375 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
376
377 if (val_is_negative(rhs_type, rhs))
378 pr_err("shift exponent %s is negative\n", rhs_str);
379
380 else if (get_unsigned_val(rhs_type, rhs) >=
381 type_bit_width(lhs_type))
382 pr_err("shift exponent %s is too large for %u-bit type %s\n",
383 rhs_str,
384 type_bit_width(lhs_type),
385 lhs_type->type_name);
386 else if (val_is_negative(lhs_type, lhs))
387 pr_err("left shift of negative value %s\n",
388 lhs_str);
389 else
390 pr_err("left shift of %s by %s places cannot be"
391 " represented in type %s\n",
392 lhs_str, rhs_str,
393 lhs_type->type_name);
394
395 ubsan_epilogue();
396 out:
397 user_access_restore(ua_flags);
398 }
399 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
400
401
__ubsan_handle_builtin_unreachable(void * _data)402 void __ubsan_handle_builtin_unreachable(void *_data)
403 {
404 struct unreachable_data *data = _data;
405 ubsan_prologue(&data->location, "unreachable");
406 pr_err("calling __builtin_unreachable()\n");
407 ubsan_epilogue();
408 panic("can't return from __builtin_unreachable()");
409 }
410 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
411
__ubsan_handle_load_invalid_value(void * _data,void * val)412 void __ubsan_handle_load_invalid_value(void *_data, void *val)
413 {
414 struct invalid_value_data *data = _data;
415 char val_str[VALUE_LENGTH];
416
417 if (suppress_report(&data->location))
418 return;
419
420 ubsan_prologue(&data->location, "invalid-load");
421
422 val_to_string(val_str, sizeof(val_str), data->type, val);
423
424 pr_err("load of value %s is not a valid value for type %s\n",
425 val_str, data->type->type_name);
426
427 ubsan_epilogue();
428 }
429 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
430
