1
2
3
4
5
6
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
20static const char * const 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 bool suppress_report(struct source_location *loc)
49{
50 return current->in_ubsan || was_reported(loc);
51}
52
53static bool type_is_int(struct type_descriptor *type)
54{
55 return type->type_kind == type_kind_int;
56}
57
58static bool type_is_signed(struct type_descriptor *type)
59{
60 WARN_ON(!type_is_int(type));
61 return type->type_info & 1;
62}
63
64static unsigned type_bit_width(struct type_descriptor *type)
65{
66 return 1 << (type->type_info >> 1);
67}
68
69static 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
79static 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
94static 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
99static 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
110static 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
136static 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
146static 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
157
158
159
160
161 panic_on_warn = 0;
162 panic("panic_on_warn set ...\n");
163 }
164}
165
166void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs)
167{
168 struct overflow_data *data = _data;
169 char rhs_val_str[VALUE_LENGTH];
170
171 if (suppress_report(&data->location))
172 return;
173
174 ubsan_prologue(&data->location, "division-overflow");
175
176 val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
177
178 if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
179 pr_err("division of %s by -1 cannot be represented in type %s\n",
180 rhs_val_str, data->type->type_name);
181 else
182 pr_err("division by zero\n");
183
184 ubsan_epilogue();
185}
186EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
187
188static void handle_null_ptr_deref(struct type_mismatch_data_common *data)
189{
190 if (suppress_report(data->location))
191 return;
192
193 ubsan_prologue(data->location, "null-ptr-deref");
194
195 pr_err("%s null pointer of type %s\n",
196 type_check_kinds[data->type_check_kind],
197 data->type->type_name);
198
199 ubsan_epilogue();
200}
201
202static void handle_misaligned_access(struct type_mismatch_data_common *data,
203 unsigned long ptr)
204{
205 if (suppress_report(data->location))
206 return;
207
208 ubsan_prologue(data->location, "misaligned-access");
209
210 pr_err("%s misaligned address %p for type %s\n",
211 type_check_kinds[data->type_check_kind],
212 (void *)ptr, data->type->type_name);
213 pr_err("which requires %ld byte alignment\n", data->alignment);
214
215 ubsan_epilogue();
216}
217
218static void handle_object_size_mismatch(struct type_mismatch_data_common *data,
219 unsigned long ptr)
220{
221 if (suppress_report(data->location))
222 return;
223
224 ubsan_prologue(data->location, "object-size-mismatch");
225 pr_err("%s address %p with insufficient space\n",
226 type_check_kinds[data->type_check_kind],
227 (void *) ptr);
228 pr_err("for an object of type %s\n", data->type->type_name);
229 ubsan_epilogue();
230}
231
232static void ubsan_type_mismatch_common(struct type_mismatch_data_common *data,
233 unsigned long ptr)
234{
235 unsigned long flags = user_access_save();
236
237 if (!ptr)
238 handle_null_ptr_deref(data);
239 else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
240 handle_misaligned_access(data, ptr);
241 else
242 handle_object_size_mismatch(data, ptr);
243
244 user_access_restore(flags);
245}
246
247void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
248 void *ptr)
249{
250 struct type_mismatch_data_common common_data = {
251 .location = &data->location,
252 .type = data->type,
253 .alignment = data->alignment,
254 .type_check_kind = data->type_check_kind
255 };
256
257 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
258}
259EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
260
261void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr)
262{
263 struct type_mismatch_data_v1 *data = _data;
264 struct type_mismatch_data_common common_data = {
265 .location = &data->location,
266 .type = data->type,
267 .alignment = 1UL << data->log_alignment,
268 .type_check_kind = data->type_check_kind
269 };
270
271 ubsan_type_mismatch_common(&common_data, (unsigned long)ptr);
272}
273EXPORT_SYMBOL(__ubsan_handle_type_mismatch_v1);
274
275void __ubsan_handle_out_of_bounds(void *_data, void *index)
276{
277 struct out_of_bounds_data *data = _data;
278 char index_str[VALUE_LENGTH];
279
280 if (suppress_report(&data->location))
281 return;
282
283 ubsan_prologue(&data->location, "array-index-out-of-bounds");
284
285 val_to_string(index_str, sizeof(index_str), data->index_type, index);
286 pr_err("index %s is out of range for type %s\n", index_str,
287 data->array_type->type_name);
288 ubsan_epilogue();
289}
290EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
291
292void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs)
293{
294 struct shift_out_of_bounds_data *data = _data;
295 struct type_descriptor *rhs_type = data->rhs_type;
296 struct type_descriptor *lhs_type = data->lhs_type;
297 char rhs_str[VALUE_LENGTH];
298 char lhs_str[VALUE_LENGTH];
299 unsigned long ua_flags = user_access_save();
300
301 if (suppress_report(&data->location))
302 goto out;
303
304 ubsan_prologue(&data->location, "shift-out-of-bounds");
305
306 val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
307 val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
308
309 if (val_is_negative(rhs_type, rhs))
310 pr_err("shift exponent %s is negative\n", rhs_str);
311
312 else if (get_unsigned_val(rhs_type, rhs) >=
313 type_bit_width(lhs_type))
314 pr_err("shift exponent %s is too large for %u-bit type %s\n",
315 rhs_str,
316 type_bit_width(lhs_type),
317 lhs_type->type_name);
318 else if (val_is_negative(lhs_type, lhs))
319 pr_err("left shift of negative value %s\n",
320 lhs_str);
321 else
322 pr_err("left shift of %s by %s places cannot be"
323 " represented in type %s\n",
324 lhs_str, rhs_str,
325 lhs_type->type_name);
326
327 ubsan_epilogue();
328out:
329 user_access_restore(ua_flags);
330}
331EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
332
333
334void __ubsan_handle_builtin_unreachable(void *_data)
335{
336 struct unreachable_data *data = _data;
337 ubsan_prologue(&data->location, "unreachable");
338 pr_err("calling __builtin_unreachable()\n");
339 ubsan_epilogue();
340 panic("can't return from __builtin_unreachable()");
341}
342EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
343
344void __ubsan_handle_load_invalid_value(void *_data, void *val)
345{
346 struct invalid_value_data *data = _data;
347 char val_str[VALUE_LENGTH];
348
349 if (suppress_report(&data->location))
350 return;
351
352 ubsan_prologue(&data->location, "invalid-load");
353
354 val_to_string(val_str, sizeof(val_str), data->type, val);
355
356 pr_err("load of value %s is not a valid value for type %s\n",
357 val_str, data->type->type_name);
358
359 ubsan_epilogue();
360}
361EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);
362
363void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
364 unsigned long align,
365 unsigned long offset);
366void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
367 unsigned long align,
368 unsigned long offset)
369{
370 struct alignment_assumption_data *data = _data;
371 unsigned long real_ptr;
372
373 if (suppress_report(&data->location))
374 return;
375
376 ubsan_prologue(&data->location, "alignment-assumption");
377
378 if (offset)
379 pr_err("assumption of %lu byte alignment (with offset of %lu byte) for pointer of type %s failed",
380 align, offset, data->type->type_name);
381 else
382 pr_err("assumption of %lu byte alignment for pointer of type %s failed",
383 align, data->type->type_name);
384
385 real_ptr = ptr - offset;
386 pr_err("%saddress is %lu aligned, misalignment offset is %lu bytes",
387 offset ? "offset " : "", BIT(real_ptr ? __ffs(real_ptr) : 0),
388 real_ptr & (align - 1));
389
390 ubsan_epilogue();
391}
392EXPORT_SYMBOL(__ubsan_handle_alignment_assumption);
393
