1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
|
// SPDX-License-Identifier: GPL-2.0
/*
* This is for all the tests related to refcount bugs (e.g. overflow,
* underflow, reaching zero untested, etc).
*/
#include "lkdtm.h"
#include <linux/refcount.h>
#ifdef CONFIG_REFCOUNT_FULL
#define REFCOUNT_MAX (UINT_MAX - 1)
#define REFCOUNT_SATURATED UINT_MAX
#else
#define REFCOUNT_MAX INT_MAX
#define REFCOUNT_SATURATED (INT_MIN / 2)
#endif
static void overflow_check(refcount_t *ref)
{
switch (refcount_read(ref)) {
case REFCOUNT_SATURATED:
pr_info("Overflow detected: saturated\n");
break;
case REFCOUNT_MAX:
pr_warn("Overflow detected: unsafely reset to max\n");
break;
default:
pr_err("Fail: refcount wrapped to %d\n", refcount_read(ref));
}
}
/*
* A refcount_inc() above the maximum value of the refcount implementation,
* should at least saturate, and at most also WARN.
*/
void lkdtm_REFCOUNT_INC_OVERFLOW(void)
{
refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX - 1);
pr_info("attempting good refcount_inc() without overflow\n");
refcount_dec(&over);
refcount_inc(&over);
pr_info("attempting bad refcount_inc() overflow\n");
refcount_inc(&over);
refcount_inc(&over);
overflow_check(&over);
}
/* refcount_add() should behave just like refcount_inc() above. */
void lkdtm_REFCOUNT_ADD_OVERFLOW(void)
{
refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX - 1);
pr_info("attempting good refcount_add() without overflow\n");
refcount_dec(&over);
refcount_dec(&over);
refcount_dec(&over);
refcount_dec(&over);
refcount_add(4, &over);
pr_info("attempting bad refcount_add() overflow\n");
refcount_add(4, &over);
overflow_check(&over);
}
/* refcount_inc_not_zero() should behave just like refcount_inc() above. */
void lkdtm_REFCOUNT_INC_NOT_ZERO_OVERFLOW(void)
{
refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX);
pr_info("attempting bad refcount_inc_not_zero() overflow\n");
if (!refcount_inc_not_zero(&over))
pr_warn("Weird: refcount_inc_not_zero() reported zero\n");
overflow_check(&over);
}
/* refcount_add_not_zero() should behave just like refcount_inc() above. */
void lkdtm_REFCOUNT_ADD_NOT_ZERO_OVERFLOW(void)
{
refcount_t over = REFCOUNT_INIT(REFCOUNT_MAX);
pr_info("attempting bad refcount_add_not_zero() overflow\n");
if (!refcount_add_not_zero(6, &over))
pr_warn("Weird: refcount_add_not_zero() reported zero\n");
overflow_check(&over);
}
static void check_zero(refcount_t *ref)
{
switch (refcount_read(ref)) {
case REFCOUNT_SATURATED:
pr_info("Zero detected: saturated\n");
break;
case REFCOUNT_MAX:
pr_warn("Zero detected: unsafely reset to max\n");
break;
case 0:
pr_warn("Still at zero: refcount_inc/add() must not inc-from-0\n");
break;
default:
pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref));
}
}
/*
* A refcount_dec(), as opposed to a refcount_dec_and_test(), when it hits
* zero it should either saturate (when inc-from-zero isn't protected)
* or stay at zero (when inc-from-zero is protected) and should WARN for both.
*/
void lkdtm_REFCOUNT_DEC_ZERO(void)
{
refcount_t zero = REFCOUNT_INIT(2);
pr_info("attempting good refcount_dec()\n");
refcount_dec(&zero);
pr_info("attempting bad refcount_dec() to zero\n");
refcount_dec(&zero);
check_zero(&zero);
}
static void check_negative(refcount_t *ref, int start)
{
/*
* CONFIG_REFCOUNT_FULL refuses to move a refcount at all on an
* over-sub, so we have to track our starting position instead of
* looking only at zero-pinning.
*/
if (refcount_read(ref) == start) {
pr_warn("Still at %d: refcount_inc/add() must not inc-from-0\n",
start);
return;
}
switch (refcount_read(ref)) {
case REFCOUNT_SATURATED:
pr_info("Negative detected: saturated\n");
break;
case REFCOUNT_MAX:
pr_warn("Negative detected: unsafely reset to max\n");
break;
default:
pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref));
}
}
/* A refcount_dec() going negative should saturate and may WARN. */
void lkdtm_REFCOUNT_DEC_NEGATIVE(void)
{
refcount_t neg = REFCOUNT_INIT(0);
pr_info("attempting bad refcount_dec() below zero\n");
refcount_dec(&neg);
check_negative(&neg, 0);
}
/*
* A refcount_dec_and_test() should act like refcount_dec() above when
* going negative.
*/
void lkdtm_REFCOUNT_DEC_AND_TEST_NEGATIVE(void)
{
refcount_t neg = REFCOUNT_INIT(0);
pr_info("attempting bad refcount_dec_and_test() below zero\n");
if (refcount_dec_and_test(&neg))
pr_warn("Weird: refcount_dec_and_test() reported zero\n");
check_negative(&neg, 0);
}
/*
* A refcount_sub_and_test() should act like refcount_dec_and_test()
* above when going negative.
*/
void lkdtm_REFCOUNT_SUB_AND_TEST_NEGATIVE(void)
{
refcount_t neg = REFCOUNT_INIT(3);
pr_info("attempting bad refcount_sub_and_test() below zero\n");
if (refcount_sub_and_test(5, &neg))
pr_warn("Weird: refcount_sub_and_test() reported zero\n");
check_negative(&neg, 3);
}
static void check_from_zero(refcount_t *ref)
{
switch (refcount_read(ref)) {
case 0:
pr_info("Zero detected: stayed at zero\n");
break;
case REFCOUNT_SATURATED:
pr_info("Zero detected: saturated\n");
break;
case REFCOUNT_MAX:
pr_warn("Zero detected: unsafely reset to max\n");
break;
default:
pr_info("Fail: zero not detected, incremented to %d\n",
refcount_read(ref));
}
}
/*
* A refcount_inc() from zero should pin to zero or saturate and may WARN.
* Only CONFIG_REFCOUNT_FULL provides this protection currently.
*/
void lkdtm_REFCOUNT_INC_ZERO(void)
{
refcount_t zero = REFCOUNT_INIT(0);
pr_info("attempting safe refcount_inc_not_zero() from zero\n");
if (!refcount_inc_not_zero(&zero)) {
pr_info("Good: zero detected\n");
if (refcount_read(&zero) == 0)
pr_info("Correctly stayed at zero\n");
else
pr_err("Fail: refcount went past zero!\n");
} else {
pr_err("Fail: Zero not detected!?\n");
}
pr_info("attempting bad refcount_inc() from zero\n");
refcount_inc(&zero);
check_from_zero(&zero);
}
/*
* A refcount_add() should act like refcount_inc() above when starting
* at zero.
*/
void lkdtm_REFCOUNT_ADD_ZERO(void)
{
refcount_t zero = REFCOUNT_INIT(0);
pr_info("attempting safe refcount_add_not_zero() from zero\n");
if (!refcount_add_not_zero(3, &zero)) {
pr_info("Good: zero detected\n");
if (refcount_read(&zero) == 0)
pr_info("Correctly stayed at zero\n");
else
pr_err("Fail: refcount went past zero\n");
} else {
pr_err("Fail: Zero not detected!?\n");
}
pr_info("attempting bad refcount_add() from zero\n");
refcount_add(3, &zero);
check_from_zero(&zero);
}
static void check_saturated(refcount_t *ref)
{
switch (refcount_read(ref)) {
case REFCOUNT_SATURATED:
pr_info("Saturation detected: still saturated\n");
break;
case REFCOUNT_MAX:
pr_warn("Saturation detected: unsafely reset to max\n");
break;
default:
pr_err("Fail: refcount went crazy: %d\n", refcount_read(ref));
}
}
/*
* A refcount_inc() from a saturated value should at most warn about
* being saturated already.
*/
void lkdtm_REFCOUNT_INC_SATURATED(void)
{
refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
pr_info("attempting bad refcount_inc() from saturated\n");
refcount_inc(&sat);
check_saturated(&sat);
}
/* Should act like refcount_inc() above from saturated. */
void lkdtm_REFCOUNT_DEC_SATURATED(void)
{
refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
pr_info("attempting bad refcount_dec() from saturated\n");
refcount_dec(&sat);
check_saturated(&sat);
}
/* Should act like refcount_inc() above from saturated. */
void lkdtm_REFCOUNT_ADD_SATURATED(void)
{
refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
pr_info("attempting bad refcount_dec() from saturated\n");
refcount_add(8, &sat);
check_saturated(&sat);
}
/* Should act like refcount_inc() above from saturated. */
void lkdtm_REFCOUNT_INC_NOT_ZERO_SATURATED(void)
{
refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
pr_info("attempting bad refcount_inc_not_zero() from saturated\n");
if (!refcount_inc_not_zero(&sat))
pr_warn("Weird: refcount_inc_not_zero() reported zero\n");
check_saturated(&sat);
}
/* Should act like refcount_inc() above from saturated. */
void lkdtm_REFCOUNT_ADD_NOT_ZERO_SATURATED(void)
{
refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
pr_info("attempting bad refcount_add_not_zero() from saturated\n");
if (!refcount_add_not_zero(7, &sat))
pr_warn("Weird: refcount_add_not_zero() reported zero\n");
check_saturated(&sat);
}
/* Should act like refcount_inc() above from saturated. */
void lkdtm_REFCOUNT_DEC_AND_TEST_SATURATED(void)
{
refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
pr_info("attempting bad refcount_dec_and_test() from saturated\n");
if (refcount_dec_and_test(&sat))
pr_warn("Weird: refcount_dec_and_test() reported zero\n");
check_saturated(&sat);
}
/* Should act like refcount_inc() above from saturated. */
void lkdtm_REFCOUNT_SUB_AND_TEST_SATURATED(void)
{
refcount_t sat = REFCOUNT_INIT(REFCOUNT_SATURATED);
pr_info("attempting bad refcount_sub_and_test() from saturated\n");
if (refco
|