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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#include <kunit/test-bug.h>
18
19#include "ubsan.h"
20
21static const char * const type_check_kinds[] = {
22 "load of",
23 "store to",
24 "reference binding to",
25 "member access within",
26 "member call on",
27 "constructor call on",
28 "downcast of",
29 "downcast of"
30};
31
32#define REPORTED_BIT 31
33
34#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
35#define COLUMN_MASK (~(1U << REPORTED_BIT))
36#define LINE_MASK (~0U)
37#else
38#define COLUMN_MASK (~0U)
39#define LINE_MASK (~(1U << REPORTED_BIT))
40#endif
41
42#define VALUE_LENGTH 40
43
44static bool was_reported(struct source_location *location)
45{
46 return test_and_set_bit(REPORTED_BIT, &location->reported);
47}
48
49static bool suppress_report(struct source_location *loc)
50{
51 return current->in_ubsan || was_reported(loc);
52}
53
54static bool type_is_int(struct type_descriptor *type)
55{
56 return type->type_kind == type_kind_int;
57}
58
59static bool type_is_signed(struct type_descriptor *type)
60{
61 WARN_ON(!type_is_int(type));
62 return type->type_info & 1;
63}
64
65static unsigned type_bit_width(struct type_descriptor *type)
66{
67 return 1 << (type->type_info >> 1);
68}
69
70static bool is_inline_int(struct type_descriptor *type)
71{
72 unsigned inline_bits = sizeof(unsigned long)*8;
73 unsigned bits = type_bit_width(type);
74
75 WARN_ON(!type_is_int(type));
76
77 return bits <= inline_bits;
78}
79
80static s_max get_signed_val(struct type_descriptor *type, void *val)
81{
82 if (is_inline_int(type)) {
83 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
84 unsigned long ulong_val = (unsigned long)val;
85
86 return ((s_max)ulong_val) << extra_bits >> extra_bits;
87 }
88
89 if (type_bit_width(type) == 64)
90 return *(s64 *)val;
91
92 return *(s_max *)val;
93}
94
95static bool val_is_negative(struct type_descriptor *type, void *val)
96{
97 return type_is_signed(type) && get_signed_val(type, val) < 0;
98}
99
100static u_max get_unsigned_val(struct type_descriptor *type, void *val)
101{
102 if (is_inline_int(type))
103 return (unsigned long)val;
104
105 if (type_bit_width(type) == 64)
106 return *(u64 *)val;
107
108 return *(u_max *)val;
109}
110
111static void val_to_string(char *str, size_t size, struct type_descriptor *type,
112 void *value)
113{
114 if (type_is_int(type)) {
115 if (type_bit_width(type) == 128) {
116#if defined(CONFIG_ARCH_SUPPORTS_INT128)
117 u_max val = get_unsigned_val(type, value);
118
119 scnprintf(str, size, "0x%08x%08x%08x%08x",
120 (u32)(val >> 96),
121 (u32)(val >> 64),
122 (u32)(val >> 32),
123 (u32)(val));
124#else
125 WARN_ON(1);
126#endif
127 } else if (type_is_signed(type)) {
128 scnprintf(str, size, "%lld",
129 (s64)get_signed_val(type, value));
130 } else {
131 scnprintf(str, size, "%llu",
132 (u64)get_unsigned_val(type, value));
133 }
134 }
135}
136
137static void ubsan_prologue(struct source_location *loc, const char *reason)
138{
139 current->in_ubsan++;
140
141 pr_err("========================================"
142 "========================================\n");
143 pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
144 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
145
146 kunit_fail_current_test("%s in %s", reason, loc->file_name);
147}
148
149static void ubsan_epilogue(void)
150{
151 dump_stack();
152 pr_err("========================================"
153 "========================================\n");
154
155 current->in_ubsan--;
156
157 check_panic_on_warn("UBSAN");
158}
159
160void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
161{
162 struct overflow_data *data = _data;
163 char rhs_val_str[VALUE_LENGTH];
164
165 if (suppress_report(&data->location))
166 return;
167
168 ubsan_prologue(&data->location, "division-overflow");
169
170 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
171
172 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
173 pr_err("division of %s by -1 cannot be represented in type %s\n",
174 rhs_val_str, data->type->type_name);
175 else
176 pr_err("division by zero\n");
177
178 ubsan_epilogue();
179}
180EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
181
182static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
183{
184 if (suppress_report(data->location))
185 return;
186
187 ubsan_prologue(data->location, "null-ptr-deref");
188
189 pr_err("%s null pointer of type %s\n",
190 type_check_kinds[data->type_check_kind],
191 data->type->type_name);
192
193 ubsan_epilogue();
194}
195
196static void handle_misaligned_access(struct type_mismatch_data_common *data,
197 unsigned long ptr)
198{
199 if (suppress_report(data->location))
200 return;
201
202 ubsan_prologue(data->location, "misaligned-access");
203
204 pr_err("%s misaligned address %p for type %s\n",
205 type_check_kinds[data->type_check_kind],
206 (void *)ptr, data->type->type_name);
207 pr_err("which requires %ld byte alignment\n", data->alignment);
208
209 ubsan_epilogue();
210}
211
212static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
213 unsigned long ptr)
214{
215 if (suppress_report(data->location))
216 return;
217
218 ubsan_prologue(data->location, "object-size-mismatch");
219 pr_err("%s address %p with insufficient space\n",
220 type_check_kinds[data->type_check_kind],
221 (void *) ptr);
222 pr_err("for an object of type %s\n", data->type->type_name);
223 ubsan_epilogue();
224}
225
226static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
227 unsigned long ptr)
228{
229 unsigned long flags = user_access_save();
230
231 if (!ptr)
232 handle_null_ptr_deref(data);
233 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
234 handle_misaligned_access(data, ptr);
235 else
236 handle_object_size_mismatch(data, ptr);
237
238 user_access_restore(flags);
239}
240
241void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
242 void *ptr)
243{
244 struct type_mismatch_data_common common_data = {
245 .location = &data->location,
246 .type = data->type,
247 .alignment = data->alignment,
248 .type_check_kind = data->type_check_kind
249 };
250
251 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
252}
253EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
254
255void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
256{
257 struct type_mismatch_data_v1 *data = _data;
258 struct type_mismatch_data_common common_data = {
259 .location = &data->location,
260 .type = data->type,
261 .alignment = 1UL << data->log_alignment,
262 .type_check_kind = data->type_check_kind
263 };
264
265 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
266}
267EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
268
269void __ubsan_handle_out_of_bounds(void *_data, void *index)
270{
271 struct out_of_bounds_data *data = _data;
272 char index_str[VALUE_LENGTH];
273
274 if (suppress_report(&data->location))
275 return;
276
277 ubsan_prologue(&data->location, "array-index-out-of-bounds");
278
279 val_to_string(index_str, sizeof(index_str), data->index_type, index);
280 pr_err("index %s is out of range for type %s\n", index_str,
281 data->array_type->type_name);
282 ubsan_epilogue();
283}
284EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
285
286void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
287{
288 struct shift_out_of_bounds_data *data = _data;
289 struct type_descriptor *rhs_type = data->rhs_type;
290 struct type_descriptor *lhs_type = data->lhs_type;
291 char rhs_str[VALUE_LENGTH];
292 char lhs_str[VALUE_LENGTH];
293 unsigned long ua_flags = user_access_save();
294
295 if (suppress_report(&data->location))
296 goto out;
297
298 ubsan_prologue(&data->location, "shift-out-of-bounds");
299
300 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
301 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
302
303 if (val_is_negative(rhs_type, rhs))
304 pr_err("shift exponent %s is negative\n", rhs_str);
305
306 else if (get_unsigned_val(rhs_type, rhs) >=
307 type_bit_width(lhs_type))
308 pr_err("shift exponent %s is too large for %u-bit type %s\n",
309 rhs_str,
310 type_bit_width(lhs_type),
311 lhs_type->type_name);
312 else if (val_is_negative(lhs_type, lhs))
313 pr_err("left shift of negative value %s\n",
314 lhs_str);
315 else
316 pr_err("left shift of %s by %s places cannot be"
317 " represented in type %s\n",
318 lhs_str, rhs_str,
319 lhs_type->type_name);
320
321 ubsan_epilogue();
322out:
323 user_access_restore(ua_flags);
324}
325EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
326
327
328void __ubsan_handle_builtin_unreachable(void *_data)
329{
330 struct unreachable_data *data = _data;
331 ubsan_prologue(&data->location, "unreachable");
332 pr_err("calling __builtin_unreachable()\n");
333 ubsan_epilogue();
334 panic("can't return from __builtin_unreachable()");
335}
336EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
337
338void __ubsan_handle_load_invalid_value(void *_data, void *val)
339{
340 struct invalid_value_data *data = _data;
341 char val_str[VALUE_LENGTH];
342
343 if (suppress_report(&data->location))
344 return;
345
346 ubsan_prologue(&data->location, "invalid-load");
347
348 val_to_string(val_str, sizeof(val_str), data->type, val);
349
350 pr_err("load of value %s is not a valid value for type %s\n",
351 val_str, data->type->type_name);
352
353 ubsan_epilogue();
354}
355EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
356
357void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
358 unsigned long align,
359 unsigned long offset);
360void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
361 unsigned long align,
362 unsigned long offset)
363{
364 struct alignment_assumption_data *data = _data;
365 unsigned long real_ptr;
366
367 if (suppress_report(&data->location))
368 return;
369
370 ubsan_prologue(&data->location, "alignment-assumption");
371
372 if (offset)
373 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
374 align, offset, data->type->type_name);
375 else
376 pr_err("assumption of %lu byte alignment for pointer of type %s failed",
377 align, data->type->type_name);
378
379 real_ptr = ptr - offset;
380 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
381 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
382 real_ptr & (align - 1));
383
384 ubsan_epilogue();
385}
386EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);