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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 <linux/ubsan.h>
18#include <kunit/test-bug.h>
19
20#include "ubsan.h"
21
22#ifdef CONFIG_UBSAN_TRAP
23/*
24 * Only include matches for UBSAN checks that are actually compiled in.
25 * The mappings of struct SanitizerKind (the -fsanitize=xxx args) to
26 * enum SanitizerHandler (the traps) in Clang is in clang/lib/CodeGen/.
27 */
28const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type)
29{
30 switch (check_type) {
31#ifdef CONFIG_UBSAN_BOUNDS
32 /*
33 * SanitizerKind::ArrayBounds and SanitizerKind::LocalBounds
34 * emit SanitizerHandler::OutOfBounds.
35 */
36 case ubsan_out_of_bounds:
37 return "UBSAN: array index out of bounds";
38#endif
39#ifdef CONFIG_UBSAN_SHIFT
40 /*
41 * SanitizerKind::ShiftBase and SanitizerKind::ShiftExponent
42 * emit SanitizerHandler::ShiftOutOfBounds.
43 */
44 case ubsan_shift_out_of_bounds:
45 return "UBSAN: shift out of bounds";
46#endif
47#ifdef CONFIG_UBSAN_DIV_ZERO
48 /*
49 * SanitizerKind::IntegerDivideByZero emits
50 * SanitizerHandler::DivremOverflow.
51 */
52 case ubsan_divrem_overflow:
53 return "UBSAN: divide/remainder overflow";
54#endif
55#ifdef CONFIG_UBSAN_UNREACHABLE
56 /*
57 * SanitizerKind::Unreachable emits
58 * SanitizerHandler::BuiltinUnreachable.
59 */
60 case ubsan_builtin_unreachable:
61 return "UBSAN: unreachable code";
62#endif
63#if defined(CONFIG_UBSAN_BOOL) || defined(CONFIG_UBSAN_ENUM)
64 /*
65 * SanitizerKind::Bool and SanitizerKind::Enum emit
66 * SanitizerHandler::LoadInvalidValue.
67 */
68 case ubsan_load_invalid_value:
69 return "UBSAN: loading invalid value";
70#endif
71#ifdef CONFIG_UBSAN_ALIGNMENT
72 /*
73 * SanitizerKind::Alignment emits SanitizerHandler::TypeMismatch
74 * or SanitizerHandler::AlignmentAssumption.
75 */
76 case ubsan_alignment_assumption:
77 return "UBSAN: alignment assumption";
78 case ubsan_type_mismatch:
79 return "UBSAN: type mismatch";
80#endif
81 default:
82 return "UBSAN: unrecognized failure code";
83 }
84}
85
86#else
87static const char * const type_check_kinds[] = {
88 "load of",
89 "store to",
90 "reference binding to",
91 "member access within",
92 "member call on",
93 "constructor call on",
94 "downcast of",
95 "downcast of"
96};
97
98#define REPORTED_BIT 31
99
100#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
101#define COLUMN_MASK (~(1U << REPORTED_BIT))
102#define LINE_MASK (~0U)
103#else
104#define COLUMN_MASK (~0U)
105#define LINE_MASK (~(1U << REPORTED_BIT))
106#endif
107
108#define VALUE_LENGTH 40
109
110static bool was_reported(struct source_location *location)
111{
112 return test_and_set_bit(REPORTED_BIT, &location->reported);
113}
114
115static bool suppress_report(struct source_location *loc)
116{
117 return current->in_ubsan || was_reported(loc);
118}
119
120static bool type_is_int(struct type_descriptor *type)
121{
122 return type->type_kind == type_kind_int;
123}
124
125static bool type_is_signed(struct type_descriptor *type)
126{
127 WARN_ON(!type_is_int(type));
128 return type->type_info & 1;
129}
130
131static unsigned type_bit_width(struct type_descriptor *type)
132{
133 return 1 << (type->type_info >> 1);
134}
135
136static bool is_inline_int(struct type_descriptor *type)
137{
138 unsigned inline_bits = sizeof(unsigned long)*8;
139 unsigned bits = type_bit_width(type);
140
141 WARN_ON(!type_is_int(type));
142
143 return bits <= inline_bits;
144}
145
146static s_max get_signed_val(struct type_descriptor *type, void *val)
147{
148 if (is_inline_int(type)) {
149 unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
150 unsigned long ulong_val = (unsigned long)val;
151
152 return ((s_max)ulong_val) << extra_bits >> extra_bits;
153 }
154
155 if (type_bit_width(type) == 64)
156 return *(s64 *)val;
157
158 return *(s_max *)val;
159}
160
161static bool val_is_negative(struct type_descriptor *type, void *val)
162{
163 return type_is_signed(type) && get_signed_val(type, val) < 0;
164}
165
166static u_max get_unsigned_val(struct type_descriptor *type, void *val)
167{
168 if (is_inline_int(type))
169 return (unsigned long)val;
170
171 if (type_bit_width(type) == 64)
172 return *(u64 *)val;
173
174 return *(u_max *)val;
175}
176
177static void val_to_string(char *str, size_t size, struct type_descriptor *type,
178 void *value)
179{
180 if (type_is_int(type)) {
181 if (type_bit_width(type) == 128) {
182#if defined(CONFIG_ARCH_SUPPORTS_INT128)
183 u_max val = get_unsigned_val(type, value);
184
185 scnprintf(str, size, "0x%08x%08x%08x%08x",
186 (u32)(val >> 96),
187 (u32)(val >> 64),
188 (u32)(val >> 32),
189 (u32)(val));
190#else
191 WARN_ON(1);
192#endif
193 } else if (type_is_signed(type)) {
194 scnprintf(str, size, "%lld",
195 (s64)get_signed_val(type, value));
196 } else {
197 scnprintf(str, size, "%llu",
198 (u64)get_unsigned_val(type, value));
199 }
200 }
201}
202
203static void ubsan_prologue(struct source_location *loc, const char *reason)
204{
205 current->in_ubsan++;
206
207 pr_warn(CUT_HERE);
208
209 pr_err("UBSAN: %s in %s:%d:%d\n", reason, loc->file_name,
210 loc->line & LINE_MASK, loc->column & COLUMN_MASK);
211
212 kunit_fail_current_test("%s in %s", reason, loc->file_name);
213}
214
215static void ubsan_epilogue(void)
216{
217 dump_stack();
218 pr_warn("---[ end trace ]---\n");
219
220 current->in_ubsan--;
221
222 check_panic_on_warn("UBSAN");
223}
224
225void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
226{
227 struct overflow_data *data = _data;
228 char rhs_val_str[VALUE_LENGTH];
229
230 if (suppress_report(&data->location))
231 return;
232
233 ubsan_prologue(&data->location, "division-overflow");
234
235 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
236
237 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
238 pr_err("division of %s by -1 cannot be represented in type %s\n",
239 rhs_val_str, data->type->type_name);
240 else
241 pr_err("division by zero\n");
242
243 ubsan_epilogue();
244}
245EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
246
247static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
248{
249 if (suppress_report(data->location))
250 return;
251
252 ubsan_prologue(data->location, "null-ptr-deref");
253
254 pr_err("%s null pointer of type %s\n",
255 type_check_kinds[data->type_check_kind],
256 data->type->type_name);
257
258 ubsan_epilogue();
259}
260
261static void handle_misaligned_access(struct type_mismatch_data_common *data,
262 unsigned long ptr)
263{
264 if (suppress_report(data->location))
265 return;
266
267 ubsan_prologue(data->location, "misaligned-access");
268
269 pr_err("%s misaligned address %p for type %s\n",
270 type_check_kinds[data->type_check_kind],
271 (void *)ptr, data->type->type_name);
272 pr_err("which requires %ld byte alignment\n", data->alignment);
273
274 ubsan_epilogue();
275}
276
277static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
278 unsigned long ptr)
279{
280 if (suppress_report(data->location))
281 return;
282
283 ubsan_prologue(data->location, "object-size-mismatch");
284 pr_err("%s address %p with insufficient space\n",
285 type_check_kinds[data->type_check_kind],
286 (void *) ptr);
287 pr_err("for an object of type %s\n", data->type->type_name);
288 ubsan_epilogue();
289}
290
291static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
292 unsigned long ptr)
293{
294 unsigned long flags = user_access_save();
295
296 if (!ptr)
297 handle_null_ptr_deref(data);
298 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
299 handle_misaligned_access(data, ptr);
300 else
301 handle_object_size_mismatch(data, ptr);
302
303 user_access_restore(flags);
304}
305
306void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
307 void *ptr)
308{
309 struct type_mismatch_data_common common_data = {
310 .location = &data->location,
311 .type = data->type,
312 .alignment = data->alignment,
313 .type_check_kind = data->type_check_kind
314 };
315
316 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
317}
318EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
319
320void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
321{
322 struct type_mismatch_data_v1 *data = _data;
323 struct type_mismatch_data_common common_data = {
324 .location = &data->location,
325 .type = data->type,
326 .alignment = 1UL << data->log_alignment,
327 .type_check_kind = data->type_check_kind
328 };
329
330 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
331}
332EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
333
334void __ubsan_handle_out_of_bounds(void *_data, void *index)
335{
336 struct out_of_bounds_data *data = _data;
337 char index_str[VALUE_LENGTH];
338
339 if (suppress_report(&data->location))
340 return;
341
342 ubsan_prologue(&data->location, "array-index-out-of-bounds");
343
344 val_to_string(index_str, sizeof(index_str), data->index_type, index);
345 pr_err("index %s is out of range for type %s\n", index_str,
346 data->array_type->type_name);
347 ubsan_epilogue();
348}
349EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
350
351void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
352{
353 struct shift_out_of_bounds_data *data = _data;
354 struct type_descriptor *rhs_type = data->rhs_type;
355 struct type_descriptor *lhs_type = data->lhs_type;
356 char rhs_str[VALUE_LENGTH];
357 char lhs_str[VALUE_LENGTH];
358 unsigned long ua_flags = user_access_save();
359
360 if (suppress_report(&data->location))
361 goto out;
362
363 ubsan_prologue(&data->location, "shift-out-of-bounds");
364
365 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
366 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
367
368 if (val_is_negative(rhs_type, rhs))
369 pr_err("shift exponent %s is negative\n", rhs_str);
370
371 else if (get_unsigned_val(rhs_type, rhs) >=
372 type_bit_width(lhs_type))
373 pr_err("shift exponent %s is too large for %u-bit type %s\n",
374 rhs_str,
375 type_bit_width(lhs_type),
376 lhs_type->type_name);
377 else if (val_is_negative(lhs_type, lhs))
378 pr_err("left shift of negative value %s\n",
379 lhs_str);
380 else
381 pr_err("left shift of %s by %s places cannot be"
382 " represented in type %s\n",
383 lhs_str, rhs_str,
384 lhs_type->type_name);
385
386 ubsan_epilogue();
387out:
388 user_access_restore(ua_flags);
389}
390EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
391
392
393void __ubsan_handle_builtin_unreachable(void *_data)
394{
395 struct unreachable_data *data = _data;
396 ubsan_prologue(&data->location, "unreachable");
397 pr_err("calling __builtin_unreachable()\n");
398 ubsan_epilogue();
399 panic("can't return from __builtin_unreachable()");
400}
401EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
402
403void __ubsan_handle_load_invalid_value(void *_data, void *val)
404{
405 struct invalid_value_data *data = _data;
406 char val_str[VALUE_LENGTH];
407 unsigned long ua_flags = user_access_save();
408
409 if (suppress_report(&data->location))
410 goto out;
411
412 ubsan_prologue(&data->location, "invalid-load");
413
414 val_to_string(val_str, sizeof(val_str), data->type, val);
415
416 pr_err("load of value %s is not a valid value for type %s\n",
417 val_str, data->type->type_name);
418
419 ubsan_epilogue();
420out:
421 user_access_restore(ua_flags);
422}
423EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
424
425void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
426 unsigned long align,
427 unsigned long offset)
428{
429 struct alignment_assumption_data *data = _data;
430 unsigned long real_ptr;
431
432 if (suppress_report(&data->location))
433 return;
434
435 ubsan_prologue(&data->location, "alignment-assumption");
436
437 if (offset)
438 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
439 align, offset, data->type->type_name);
440 else
441 pr_err("assumption of %lu byte alignment for pointer of type %s failed",
442 align, data->type->type_name);
443
444 real_ptr = ptr - offset;
445 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
446 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
447 real_ptr & (align - 1));
448
449 ubsan_epilogue();
450}
451EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);
452
453#endif /* !CONFIG_UBSAN_TRAP */