Merge tag 'for-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power...
[platform/kernel/linux-rpi.git] / lib / ubsan.c
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  */
28 const 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
87 static 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
110 static bool was_reported(struct source_location *location)
111 {
112         return test_and_set_bit(REPORTED_BIT, &location->reported);
113 }
114
115 static bool suppress_report(struct source_location *loc)
116 {
117         return current->in_ubsan || was_reported(loc);
118 }
119
120 static bool type_is_int(struct type_descriptor *type)
121 {
122         return type->type_kind == type_kind_int;
123 }
124
125 static bool type_is_signed(struct type_descriptor *type)
126 {
127         WARN_ON(!type_is_int(type));
128         return  type->type_info & 1;
129 }
130
131 static unsigned type_bit_width(struct type_descriptor *type)
132 {
133         return 1 << (type->type_info >> 1);
134 }
135
136 static 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
146 static 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
161 static 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
166 static 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
177 static 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
203 static void ubsan_prologue(struct source_location *loc, const char *reason)
204 {
205         current->in_ubsan++;
206
207         pr_err("========================================"
208                 "========================================\n");
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
215 static void ubsan_epilogue(void)
216 {
217         dump_stack();
218         pr_err("========================================"
219                 "========================================\n");
220
221         current->in_ubsan--;
222
223         check_panic_on_warn("UBSAN");
224 }
225
226 void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
227 {
228         struct overflow_data *data = _data;
229         char rhs_val_str[VALUE_LENGTH];
230
231         if (suppress_report(&data->location))
232                 return;
233
234         ubsan_prologue(&data->location, "division-overflow");
235
236         val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
237
238         if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
239                 pr_err("division of %s by -1 cannot be represented in type %s\n",
240                         rhs_val_str, data->type->type_name);
241         else
242                 pr_err("division by zero\n");
243
244         ubsan_epilogue();
245 }
246 EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
247
248 static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
249 {
250         if (suppress_report(data->location))
251                 return;
252
253         ubsan_prologue(data->location, "null-ptr-deref");
254
255         pr_err("%s null pointer of type %s\n",
256                 type_check_kinds[data->type_check_kind],
257                 data->type->type_name);
258
259         ubsan_epilogue();
260 }
261
262 static void handle_misaligned_access(struct type_mismatch_data_common *data,
263                                 unsigned long ptr)
264 {
265         if (suppress_report(data->location))
266                 return;
267
268         ubsan_prologue(data->location, "misaligned-access");
269
270         pr_err("%s misaligned address %p for type %s\n",
271                 type_check_kinds[data->type_check_kind],
272                 (void *)ptr, data->type->type_name);
273         pr_err("which requires %ld byte alignment\n", data->alignment);
274
275         ubsan_epilogue();
276 }
277
278 static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
279                                         unsigned long ptr)
280 {
281         if (suppress_report(data->location))
282                 return;
283
284         ubsan_prologue(data->location, "object-size-mismatch");
285         pr_err("%s address %p with insufficient space\n",
286                 type_check_kinds[data->type_check_kind],
287                 (void *) ptr);
288         pr_err("for an object of type %s\n", data->type->type_name);
289         ubsan_epilogue();
290 }
291
292 static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
293                                 unsigned long ptr)
294 {
295         unsigned long flags = user_access_save();
296
297         if (!ptr)
298                 handle_null_ptr_deref(data);
299         else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
300                 handle_misaligned_access(data, ptr);
301         else
302                 handle_object_size_mismatch(data, ptr);
303
304         user_access_restore(flags);
305 }
306
307 void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
308                                 void *ptr)
309 {
310         struct type_mismatch_data_common common_data = {
311                 .location = &data->location,
312                 .type = data->type,
313                 .alignment = data->alignment,
314                 .type_check_kind = data->type_check_kind
315         };
316
317         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
318 }
319 EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
320
321 void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
322 {
323         struct type_mismatch_data_v1 *data = _data;
324         struct type_mismatch_data_common common_data = {
325                 .location = &data->location,
326                 .type = data->type,
327                 .alignment = 1UL << data->log_alignment,
328                 .type_check_kind = data->type_check_kind
329         };
330
331         ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
332 }
333 EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
334
335 void __ubsan_handle_out_of_bounds(void *_data, void *index)
336 {
337         struct out_of_bounds_data *data = _data;
338         char index_str[VALUE_LENGTH];
339
340         if (suppress_report(&data->location))
341                 return;
342
343         ubsan_prologue(&data->location, "array-index-out-of-bounds");
344
345         val_to_string(index_str, sizeof(index_str), data->index_type, index);
346         pr_err("index %s is out of range for type %s\n", index_str,
347                 data->array_type->type_name);
348         ubsan_epilogue();
349 }
350 EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
351
352 void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
353 {
354         struct shift_out_of_bounds_data *data = _data;
355         struct type_descriptor *rhs_type = data->rhs_type;
356         struct type_descriptor *lhs_type = data->lhs_type;
357         char rhs_str[VALUE_LENGTH];
358         char lhs_str[VALUE_LENGTH];
359         unsigned long ua_flags = user_access_save();
360
361         if (suppress_report(&data->location))
362                 goto out;
363
364         ubsan_prologue(&data->location, "shift-out-of-bounds");
365
366         val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
367         val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
368
369         if (val_is_negative(rhs_type, rhs))
370                 pr_err("shift exponent %s is negative\n", rhs_str);
371
372         else if (get_unsigned_val(rhs_type, rhs) >=
373                 type_bit_width(lhs_type))
374                 pr_err("shift exponent %s is too large for %u-bit type %s\n",
375                         rhs_str,
376                         type_bit_width(lhs_type),
377                         lhs_type->type_name);
378         else if (val_is_negative(lhs_type, lhs))
379                 pr_err("left shift of negative value %s\n",
380                         lhs_str);
381         else
382                 pr_err("left shift of %s by %s places cannot be"
383                         " represented in type %s\n",
384                         lhs_str, rhs_str,
385                         lhs_type->type_name);
386
387         ubsan_epilogue();
388 out:
389         user_access_restore(ua_flags);
390 }
391 EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
392
393
394 void __ubsan_handle_builtin_unreachable(void *_data)
395 {
396         struct unreachable_data *data = _data;
397         ubsan_prologue(&data->location, "unreachable");
398         pr_err("calling __builtin_unreachable()\n");
399         ubsan_epilogue();
400         panic("can't return from __builtin_unreachable()");
401 }
402 EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
403
404 void __ubsan_handle_load_invalid_value(void *_data, void *val)
405 {
406         struct invalid_value_data *data = _data;
407         char val_str[VALUE_LENGTH];
408         unsigned long ua_flags = user_access_save();
409
410         if (suppress_report(&data->location))
411                 goto out;
412
413         ubsan_prologue(&data->location, "invalid-load");
414
415         val_to_string(val_str, sizeof(val_str), data->type, val);
416
417         pr_err("load of value %s is not a valid value for type %s\n",
418                 val_str, data->type->type_name);
419
420         ubsan_epilogue();
421 out:
422         user_access_restore(ua_flags);
423 }
424 EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
425
426 void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
427                                          unsigned long align,
428                                          unsigned long offset)
429 {
430         struct alignment_assumption_data *data = _data;
431         unsigned long real_ptr;
432
433         if (suppress_report(&data->location))
434                 return;
435
436         ubsan_prologue(&data->location, "alignment-assumption");
437
438         if (offset)
439                 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
440                        align, offset, data->type->type_name);
441         else
442                 pr_err("assumption of %lu byte alignment for pointer of type %s failed",
443                        align, data->type->type_name);
444
445         real_ptr = ptr - offset;
446         pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
447                offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
448                real_ptr & (align - 1));
449
450         ubsan_epilogue();
451 }
452 EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);
453
454 #endif /* !CONFIG_UBSAN_TRAP */