summaryrefslogtreecommitdiffstats
path: root/lib/fortify_kunit.c
blob: fdba0eaf19a59d6bb2fc97b29cb71eba5938bf29 (plain)
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
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
// SPDX-License-Identifier: GPL-2.0
/*
 * Runtime test cases for CONFIG_FORTIFY_SOURCE. For testing memcpy(),
 * see FORTIFY_MEM_* tests in LKDTM (drivers/misc/lkdtm/fortify.c).
 *
 * For corner cases with UBSAN, try testing with:
 *
 * ./tools/testing/kunit/kunit.py run --arch=x86_64 \
 *	--kconfig_add CONFIG_FORTIFY_SOURCE=y \
 *	--kconfig_add CONFIG_UBSAN=y \
 *	--kconfig_add CONFIG_UBSAN_TRAP=y \
 *	--kconfig_add CONFIG_UBSAN_BOUNDS=y \
 *	--kconfig_add CONFIG_UBSAN_LOCAL_BOUNDS=y \
 *	--make_options LLVM=1 fortify
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

/* Redefine fortify_panic() to track failures. */
void fortify_add_kunit_error(int write);
#define fortify_panic(func, write, avail, size, retfail) do {		\
	__fortify_report(FORTIFY_REASON(func, write), avail, size);	\
	fortify_add_kunit_error(write);					\
	return (retfail);						\
} while (0)

#include <kunit/device.h>
#include <kunit/test.h>
#include <kunit/test-bug.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/vmalloc.h>

/* Handle being built without CONFIG_FORTIFY_SOURCE */
#ifndef __compiletime_strlen
# define __compiletime_strlen __builtin_strlen
#endif

static struct kunit_resource read_resource;
static struct kunit_resource write_resource;
static int fortify_read_overflows;
static int fortify_write_overflows;

static const char array_of_10[] = "this is 10";
static const char *ptr_of_11 = "this is 11!";
static char array_unknown[] = "compiler thinks I might change";

void fortify_add_kunit_error(int write)
{
	struct kunit_resource *resource;
	struct kunit *current_test;

	current_test = kunit_get_current_test();
	if (!current_test)
		return;

	resource = kunit_find_named_resource(current_test,
			write ? "fortify_write_overflows"
			      : "fortify_read_overflows");
	if (!resource)
		return;

	(*(int *)resource->data)++;
	kunit_put_resource(resource);
}

static void known_sizes_test(struct kunit *test)
{
	KUNIT_EXPECT_EQ(test, __compiletime_strlen("88888888"), 8);
	KUNIT_EXPECT_EQ(test, __compiletime_strlen(array_of_10), 10);
	KUNIT_EXPECT_EQ(test, __compiletime_strlen(ptr_of_11), 11);

	KUNIT_EXPECT_EQ(test, __compiletime_strlen(array_unknown), SIZE_MAX);
	/* Externally defined and dynamically sized string pointer: */
	KUNIT_EXPECT_EQ(test, __compiletime_strlen(test->name), SIZE_MAX);
}

/* This is volatile so the optimizer can't perform DCE below. */
static volatile int pick;

/* Not inline to keep optimizer from figuring out which string we want. */
static noinline size_t want_minus_one(int pick)
{
	const char *str;

	switch (pick) {
	case 1:
		str = "4444";
		break;
	case 2:
		str = "333";
		break;
	default:
		str = "1";
		break;
	}
	return __compiletime_strlen(str);
}

static void control_flow_split_test(struct kunit *test)
{
	KUNIT_EXPECT_EQ(test, want_minus_one(pick), SIZE_MAX);
}

#define KUNIT_EXPECT_BOS(test, p, expected, name)			\
	KUNIT_EXPECT_EQ_MSG(test, __builtin_object_size(p, 1),		\
		expected,						\
		"__alloc_size() not working with __bos on " name "\n")

#if !__has_builtin(__builtin_dynamic_object_size)
#define KUNIT_EXPECT_BDOS(test, p, expected, name)			\
	/* Silence "unused variable 'expected'" warning. */		\
	KUNIT_EXPECT_EQ(test, expected, expected)
#else
#define KUNIT_EXPECT_BDOS(test, p, expected, name)			\
	KUNIT_EXPECT_EQ_MSG(test, __builtin_dynamic_object_size(p, 1),	\
		expected,						\
		"__alloc_size() not working with __bdos on " name "\n")
#endif

/* If the execpted size is a constant value, __bos can see it. */
#define check_const(_expected, alloc, free)		do {		\
	size_t expected = (_expected);					\
	void *p = alloc;						\
	KUNIT_EXPECT_TRUE_MSG(test, p != NULL, #alloc " failed?!\n");	\
	KUNIT_EXPECT_BOS(test, p, expected, #alloc);			\
	KUNIT_EXPECT_BDOS(test, p, expected, #alloc);			\
	free;								\
} while (0)

/* If the execpted size is NOT a constant value, __bos CANNOT see it. */
#define check_dynamic(_expected, alloc, free)		do {		\
	size_t expected = (_expected);					\
	void *p = alloc;						\
	KUNIT_EXPECT_TRUE_MSG(test, p != NULL, #alloc " failed?!\n");	\
	KUNIT_EXPECT_BOS(test, p, SIZE_MAX, #alloc);			\
	KUNIT_EXPECT_BDOS(test, p, expected, #alloc);			\
	free;								\
} while (0)

/* Assortment of constant-value kinda-edge cases. */
#define CONST_TEST_BODY(TEST_alloc)	do {				\
	/* Special-case vmalloc()-family to skip 0-sized allocs. */	\
	if (strcmp(#TEST_alloc, "TEST_vmalloc") != 0)			\
		TEST_alloc(check_const, 0, 0);				\
	TEST_alloc(check_const, 1, 1);					\
	TEST_alloc(check_const, 128, 128);				\
	TEST_alloc(check_const, 1023, 1023);				\
	TEST_alloc(check_const, 1025, 1025);				\
	TEST_alloc(check_const, 4096, 4096);				\
	TEST_alloc(check_const, 4097, 4097);				\
} while (0)

static volatile size_t zero_size;
static volatile size_t unknown_size = 50;

#if !__has_builtin(__builtin_dynamic_object_size)
#define DYNAMIC_TEST_BODY(TEST_alloc)					\
	kunit_skip(test, "Compiler is missing __builtin_dynamic_object_size() support\n")
#else
#define DYNAMIC_TEST_BODY(TEST_alloc)	do {				\
	size_t size = unknown_size;					\
									\
	/*								\
	 * Expected size is "size" in each test, before it is then	\
	 * internally incremented in each test.	Requires we disable	\
	 * -Wunsequenced.						\
	 */								\
	TEST_alloc(check_dynamic, size, size++);			\
	/* Make sure incrementing actually happened. */			\
	KUNIT_EXPECT_NE(test, size, unknown_size);			\
} while (0)
#endif

#define DEFINE_ALLOC_SIZE_TEST_PAIR(allocator)				\
static void alloc_size_##allocator##_const_test(struct kunit *test)	\
{									\
	CONST_TEST_BODY(TEST_##allocator);				\
}									\
static void alloc_size_##allocator##_dynamic_test(struct kunit *test)	\
{									\
	DYNAMIC_TEST_BODY(TEST_##allocator);				\
}

#define TEST_kmalloc(checker, expected_size, alloc_size)	do {	\
	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
	void *orig;							\
	size_t len;							\
									\
	checker(expected_size, kmalloc(alloc_size, gfp),		\
		kfree(p));						\
	checker(expected_size,						\
		kmalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
		kfree(p));						\
	checker(expected_size, kzalloc(alloc_size, gfp),		\
		kfree(p));						\
	checker(expected_size,						\
		kzalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
		kfree(p));						\
	checker(expected_size, kcalloc(1, alloc_size, gfp),		\
		kfree(p));						\
	checker(expected_size, kcalloc(alloc_size, 1, gfp),		\
		kfree(p));						\
	checker(expected_size,						\
		kcalloc_node(1, alloc_size, gfp, NUMA_NO_NODE),		\
		kfree(p));						\
	checker(expected_size,						\
		kcalloc_node(alloc_size, 1, gfp, NUMA_NO_NODE),		\
		kfree(p));						\
	checker(expected_size, kmalloc_array(1, alloc_size, gfp),	\
		kfree(p));						\
	checker(expected_size, kmalloc_array(alloc_size, 1, gfp),	\
		kfree(p));						\
	checker(expected_size,						\
		kmalloc_array_node(1, alloc_size, gfp, NUMA_NO_NODE),	\
		kfree(p));						\
	checker(expected_size,						\
		kmalloc_array_node(alloc_size, 1, gfp, NUMA_NO_NODE),	\
		kfree(p));						\
	checker(expected_size, __kmalloc(alloc_size, gfp),		\
		kfree(p));						\
	checker(expected_size,						\
		__kmalloc_node(alloc_size, gfp, NUMA_NO_NODE),		\
		kfree(p));						\
									\
	orig = kmalloc(alloc_size, gfp);				\
	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
	checker((expected_size) * 2,					\
		krealloc(orig, (alloc_size) * 2, gfp),			\
		kfree(p));						\
	orig = kmalloc(alloc_size, gfp);				\
	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
	checker((expected_size) * 2,					\
		krealloc_array(orig, 1, (alloc_size) * 2, gfp),		\
		kfree(p));						\
	orig = kmalloc(alloc_size, gfp);				\
	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
	checker((expected_size) * 2,					\
		krealloc_array(orig, (alloc_size) * 2, 1, gfp),		\
		kfree(p));						\
									\
	len = 11;							\
	/* Using memdup() with fixed size, so force unknown length. */	\
	if (!__builtin_constant_p(expected_size))			\
		len += zero_size;					\
	checker(len, kmemdup("hello there", len, gfp), kfree(p));	\
} while (0)
DEFINE_ALLOC_SIZE_TEST_PAIR(kmalloc)

/* Sizes are in pages, not bytes. */
#define TEST_vmalloc(checker, expected_pages, alloc_pages)	do {	\
	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
	checker((expected_pages) * PAGE_SIZE,				\
		vmalloc((alloc_pages) * PAGE_SIZE),	   vfree(p));	\
	checker((expected_pages) * PAGE_SIZE,				\
		vzalloc((alloc_pages) * PAGE_SIZE),	   vfree(p));	\
	checker((expected_pages) * PAGE_SIZE,				\
		__vmalloc((alloc_pages) * PAGE_SIZE, gfp), vfree(p));	\
} while (0)
DEFINE_ALLOC_SIZE_TEST_PAIR(vmalloc)

/* Sizes are in pages (and open-coded for side-effects), not bytes. */
#define TEST_kvmalloc(checker, expected_pages, alloc_pages)	do {	\
	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
	size_t prev_size;						\
	void *orig;							\
									\
	checker((expected_pages) * PAGE_SIZE,				\
		kvmalloc((alloc_pages) * PAGE_SIZE, gfp),		\
		kvfree(p));						\
	checker((expected_pages) * PAGE_SIZE,				\
		kvmalloc_node((alloc_pages) * PAGE_SIZE, gfp, NUMA_NO_NODE), \
		kvfree(p));						\
	checker((expected_pages) * PAGE_SIZE,				\
		kvzalloc((alloc_pages) * PAGE_SIZE, gfp),		\
		kvfree(p));						\
	checker((expected_pages) * PAGE_SIZE,				\
		kvzalloc_node((alloc_pages) * PAGE_SIZE, gfp, NUMA_NO_NODE), \
		kvfree(p));						\
	checker((expected_pages) * PAGE_SIZE,				\
		kvcalloc(1, (alloc_pages) * PAGE_SIZE, gfp),		\
		kvfree(p));						\
	checker((expected_pages) * PAGE_SIZE,				\
		kvcalloc((alloc_pages) * PAGE_SIZE, 1, gfp),		\
		kvfree(p));						\
	checker((expected_pages) * PAGE_SIZE,				\
		kvmalloc_array(1, (alloc_pages) * PAGE_SIZE, gfp),	\
		kvfree(p));						\
	checker((expected_pages) * PAGE_SIZE,				\
		kvmalloc_array((alloc_pages) * PAGE_SIZE, 1, gfp),	\
		kvfree(p));						\
									\
	prev_size = (expected_pages) * PAGE_SIZE;			\
	orig = kvmalloc(prev_size, gfp);				\
	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
	checker(((expected_pages) * PAGE_SIZE) * 2,			\
		kvrealloc(orig, prev_size,				\
			  ((alloc_pages) * PAGE_SIZE) * 2, gfp),	\
		kvfree(p));						\
} while (0)
DEFINE_ALLOC_SIZE_TEST_PAIR(kvmalloc)

#define TEST_devm_kmalloc(checker, expected_size, alloc_size)	do {	\
	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;				\
	const char dev_name[] = "fortify-test";				\
	struct device *dev;						\
	void *orig;							\
	size_t len;							\
									\
	/* Create dummy device for devm_kmalloc()-family tests. */	\
	dev = kunit_device_register(test, dev_name);			\
	KUNIT_ASSERT_FALSE_MSG(test, IS_ERR(dev),			\
			       "Cannot register test device\n");	\
									\
	checker(expected_size, devm_kmalloc(dev, alloc_size, gfp),	\
		devm_kfree(dev, p));					\
	checker(expected_size, devm_kzalloc(dev, alloc_size, gfp),	\
		devm_kfree(dev, p));					\
	checker(expected_size,						\
		devm_kmalloc_array(dev, 1, alloc_size, gfp),		\
		devm_kfree(dev, p));					\
	checker(expected_size,						\
		devm_kmalloc_array(dev, alloc_size, 1, gfp),		\
		devm_kfree(dev, p));					\
	checker(expected_size,						\
		devm_kcalloc(dev, 1, alloc_size, gfp),			\
		devm_kfree(dev, p));					\
	checker(expected_size,						\
		devm_kcalloc(dev, alloc_size, 1, gfp),			\
		devm_kfree(dev, p));					\
									\
	orig = devm_kmalloc(dev, alloc_size, gfp);			\
	KUNIT_EXPECT_TRUE(test, orig != NULL);				\
	checker((expected_size) * 2,					\
		devm_krealloc(dev, orig, (alloc_size) * 2, gfp),	\
		devm_kfree(dev, p));					\
									\
	len = 4;							\
	/* Using memdup() with fixed size, so force unknown length. */	\
	if (!__builtin_constant_p(expected_size))			\
		len += zero_size;					\
	checker(len, devm_kmemdup(dev, "Ohai", len, gfp),		\
		devm_kfree(dev, p));					\
									\
	kunit_device_unregister(test, dev);				\
} while (0)
DEFINE_ALLOC_SIZE_TEST_PAIR(devm_kmalloc)

/*
 * We can't have an array at the end of a structure or else
 * builds without -fstrict-flex-arrays=3 will report them as
 * being an unknown length. Additionally, add bytes before
 * and after the string to catch over/underflows if tests
 * fail.
 */
struct fortify_padding {
	unsigned long bytes_before;
	char buf[32];
	unsigned long bytes_after;
};
/* Force compiler into not being able to resolve size at compile-time. */
static volatile int unconst;

static void strlen_test(struct kunit *test)
{
	struct fortify_padding pad = { };
	int i, end = sizeof(pad.buf) - 1;

	/* Fill 31 bytes with valid characters. */
	for (i = 0; i < sizeof(pad.buf) - 1; i++)
		pad.buf[i] = i + '0';
	/* Trailing bytes are still %NUL. */
	KUNIT_EXPECT_EQ(test, pad.buf[end], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* String is terminated, so strlen() is valid. */
	KUNIT_EXPECT_EQ(test, strlen(pad.buf), end);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);

	/* Make string unterminated, and recount. */
	pad.buf[end] = 'A';
	end = sizeof(pad.buf);
	KUNIT_EXPECT_EQ(test, strlen(pad.buf), end);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
}

static void strnlen_test(struct kunit *test)
{
	struct fortify_padding pad = { };
	int i, end = sizeof(pad.buf) - 1;

	/* Fill 31 bytes with valid characters. */
	for (i = 0; i < sizeof(pad.buf) - 1; i++)
		pad.buf[i] = i + '0';
	/* Trailing bytes are still %NUL. */
	KUNIT_EXPECT_EQ(test, pad.buf[end], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* String is terminated, so strnlen() is valid. */
	KUNIT_EXPECT_EQ(test, strnlen(pad.buf, sizeof(pad.buf)), end);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	/* A truncated strnlen() will be safe, too. */
	KUNIT_EXPECT_EQ(test, strnlen(pad.buf, sizeof(pad.buf) / 2),
					sizeof(pad.buf) / 2);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);

	/* Make string unterminated, and recount. */
	pad.buf[end] = 'A';
	end = sizeof(pad.buf);
	/* Reading beyond with strncpy() will fail. */
	KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end + 1), end);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
	KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end + 2), end);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);

	/* Early-truncated is safe still, though. */
	KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end), end);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);

	end = sizeof(pad.buf) / 2;
	KUNIT_EXPECT_EQ(test, strnlen(pad.buf, end), end);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void strcpy_test(struct kunit *test)
{
	struct fortify_padding pad = { };
	char src[sizeof(pad.buf) + 1] = { };
	int i;

	/* Fill 31 bytes with valid characters. */
	for (i = 0; i < sizeof(src) - 2; i++)
		src[i] = i + '0';

	/* Destination is %NUL-filled to start with. */
	KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Legitimate strcpy() 1 less than of max size. */
	KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
				== pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Only last byte should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	src[sizeof(src) - 2] = 'A';
	/* But now we trip the overflow checking. */
	KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
				== pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
	/* Trailing %NUL -- thanks to FORTIFY. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	/* And we will not have gone beyond. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	src[sizeof(src) - 1] = 'A';
	/* And for sure now, two bytes past. */
	KUNIT_ASSERT_TRUE(test, strcpy(pad.buf, src)
				== pad.buf);
	/*
	 * Which trips both the strlen() on the unterminated src,
	 * and the resulting copy attempt.
	 */
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
	/* Trailing %NUL -- thanks to FORTIFY. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	/* And we will not have gone beyond. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void strncpy_test(struct kunit *test)
{
	struct fortify_padding pad = { };
	char src[] = "Copy me fully into a small buffer and I will overflow!";

	/* Destination is %NUL-filled to start with. */
	KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Legitimate strncpy() 1 less than of max size. */
	KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src,
					sizeof(pad.buf) + unconst - 1)
				== pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Only last byte should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	/* Legitimate (though unterminated) max-size strncpy. */
	KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src,
					sizeof(pad.buf) + unconst)
				== pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* No trailing %NUL -- thanks strncpy API. */
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	/* But we will not have gone beyond. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Now verify that FORTIFY is working... */
	KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src,
					sizeof(pad.buf) + unconst + 1)
				== pad.buf);
	/* Should catch the overflow. */
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	/* And we will not have gone beyond. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* And further... */
	KUNIT_ASSERT_TRUE(test, strncpy(pad.buf, src,
					sizeof(pad.buf) + unconst + 2)
				== pad.buf);
	/* Should catch the overflow. */
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	/* And we will not have gone beyond. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void strscpy_test(struct kunit *test)
{
	struct fortify_padding pad = { };
	char src[] = "Copy me fully into a small buffer and I will overflow!";

	/* Destination is %NUL-filled to start with. */
	KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Legitimate strscpy() 1 less than of max size. */
	KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src,
				      sizeof(pad.buf) + unconst - 1),
			-E2BIG);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Keeping space for %NUL, last two bytes should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	/* Legitimate max-size strscpy. */
	KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src,
				      sizeof(pad.buf) + unconst),
			-E2BIG);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* A trailing %NUL will exist. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');

	/* Now verify that FORTIFY is working... */
	KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src,
				      sizeof(pad.buf) + unconst + 1),
			-E2BIG);
	/* Should catch the overflow. */
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	/* And we will not have gone beyond. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* And much further... */
	KUNIT_ASSERT_EQ(test, strscpy(pad.buf, src,
				      sizeof(src) * 2 + unconst),
			-E2BIG);
	/* Should catch the overflow. */
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	/* And we will not have gone beyond. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void strcat_test(struct kunit *test)
{
	struct fortify_padding pad = { };
	char src[sizeof(pad.buf) / 2] = { };
	char one[] = "A";
	char two[] = "BC";
	int i;

	/* Fill 15 bytes with valid characters. */
	for (i = 0; i < sizeof(src) - 1; i++)
		src[i] = i + 'A';

	/* Destination is %NUL-filled to start with. */
	KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Legitimate strcat() using less than half max size. */
	KUNIT_ASSERT_TRUE(test, strcat(pad.buf, src) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Legitimate strcat() now 2 bytes shy of end. */
	KUNIT_ASSERT_TRUE(test, strcat(pad.buf, src) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Last two bytes should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	/* Add one more character to the end. */
	KUNIT_ASSERT_TRUE(test, strcat(pad.buf, one) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Last byte should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	/* And this one char will overflow. */
	KUNIT_ASSERT_TRUE(test, strcat(pad.buf, one) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
	/* Last byte should be %NUL thanks to FORTIFY. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* And adding two will overflow more. */
	KUNIT_ASSERT_TRUE(test, strcat(pad.buf, two) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
	/* Last byte should be %NUL thanks to FORTIFY. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void strncat_test(struct kunit *test)
{
	struct fortify_padding pad = { };
	char src[sizeof(pad.buf)] = { };
	int i, partial;

	/* Fill 31 bytes with valid characters. */
	partial = sizeof(src) / 2 - 1;
	for (i = 0; i < partial; i++)
		src[i] = i + 'A';

	/* Destination is %NUL-filled to start with. */
	KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Legitimate strncat() using less than half max size. */
	KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, partial) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Legitimate strncat() now 2 bytes shy of end. */
	KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, partial) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Last two bytes should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	/* Add one more character to the end. */
	KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Last byte should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	/* And this one char will overflow. */
	KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
	/* Last byte should be %NUL thanks to FORTIFY. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* And adding two will overflow more. */
	KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 2) == pad.buf);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
	/* Last byte should be %NUL thanks to FORTIFY. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Force an unterminated destination, and overflow. */
	pad.buf[sizeof(pad.buf) - 1] = 'A';
	KUNIT_ASSERT_TRUE(test, strncat(pad.buf, src, 1) == pad.buf);
	/* This will have tripped both strlen() and strcat(). */
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 3);
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	/* But we should not go beyond the end. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void strlcat_test(struct kunit *test)
{
	struct fortify_padding pad = { };
	char src[sizeof(pad.buf)] = { };
	int i, partial;
	int len = sizeof(pad.buf) + unconst;

	/* Fill 15 bytes with valid characters. */
	partial = sizeof(src) / 2 - 1;
	for (i = 0; i < partial; i++)
		src[i] = i + 'A';

	/* Destination is %NUL-filled to start with. */
	KUNIT_EXPECT_EQ(test, pad.bytes_before, 0);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Legitimate strlcat() using less than half max size. */
	KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len), partial);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Legitimate strlcat() now 2 bytes shy of end. */
	KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len), partial * 2);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Last two bytes should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	/* Add one more character to the end. */
	KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "Q", len), partial * 2 + 1);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 0);
	/* Last byte should be %NUL */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');

	/* And this one char will overflow. */
	KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "V", len * 2), len);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 1);
	/* Last byte should be %NUL thanks to FORTIFY. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* And adding two will overflow more. */
	KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "QQ", len * 2), len + 1);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
	/* Last byte should be %NUL thanks to FORTIFY. */
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Force an unterminated destination, and overflow. */
	pad.buf[sizeof(pad.buf) - 1] = 'A';
	KUNIT_ASSERT_EQ(test, strlcat(pad.buf, "TT", len * 2), len + 2);
	/* This will have tripped both strlen() and strlcat(). */
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 2);
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 2], '\0');
	KUNIT_EXPECT_NE(test, pad.buf[sizeof(pad.buf) - 3], '\0');
	/* But we should not go beyond the end. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);

	/* Force an unterminated source, and overflow. */
	memset(src, 'B', sizeof(src));
	pad.buf[sizeof(pad.buf) - 1] = '\0';
	KUNIT_ASSERT_EQ(test, strlcat(pad.buf, src, len * 3), len - 1 + sizeof(src));
	/* This will have tripped both strlen() and strlcat(). */
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3);
	KUNIT_EXPECT_EQ(test, fortify_write_overflows, 3);
	KUNIT_EXPECT_EQ(test, pad.buf[sizeof(pad.buf) - 1], '\0');
	/* But we should not go beyond the end. */
	KUNIT_EXPECT_EQ(test, pad.bytes_after, 0);
}

static void memscan_test(struct kunit *test)
{
	char haystack[] = "Where oh where is my memory range?";
	char *mem = haystack + strlen("Where oh where is ");
	char needle = 'm';
	size_t len = sizeof(haystack) + unconst;

	KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len),
				  mem);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	/* Catch too-large range. */
	KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len + 1),
				  NULL);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
	KUNIT_ASSERT_PTR_EQ(test, memscan(haystack, needle, len * 2),
				  NULL);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void memchr_test(struct kunit *test)
{
	char haystack[] = "Where oh where is my memory range?";
	char *mem = haystack + strlen("Where oh where is ");
	char needle = 'm';
	size_t len = sizeof(haystack) + unconst;

	KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len),
				  mem);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	/* Catch too-large range. */
	KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len + 1),
				  NULL);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
	KUNIT_ASSERT_PTR_EQ(test, memchr(haystack, needle, len * 2),
				  NULL);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void memchr_inv_test(struct kunit *test)
{
	char haystack[] = "Where oh where is my memory range?";
	char *mem = haystack + 1;
	char needle = 'W';
	size_t len = sizeof(haystack) + unconst;

	/* Normal search is okay. */
	KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len),
				  mem);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	/* Catch too-large range. */
	KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len + 1),
				  NULL);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
	KUNIT_ASSERT_PTR_EQ(test, memchr_inv(haystack, needle, len * 2),
				  NULL);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void memcmp_test(struct kunit *test)
{
	char one[] = "My mind is going ...";
	char two[] = "My mind is going ... I can feel it.";
	size_t one_len = sizeof(one) + unconst - 1;
	size_t two_len = sizeof(two) + unconst - 1;

	/* We match the first string (ignoring the %NUL). */
	KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len), 0);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	/* Still in bounds, but no longer matching. */
	KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len + 1), -32);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);

	/* Catch too-large ranges. */
	KUNIT_ASSERT_EQ(test, memcmp(one, two, one_len + 2), INT_MIN);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);

	KUNIT_ASSERT_EQ(test, memcmp(two, one, two_len + 2), INT_MIN);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
}

static void kmemdup_test(struct kunit *test)
{
	char src[] = "I got Doom running on it!";
	char *copy;
	size_t len = sizeof(src) + unconst;

	/* Copy is within bounds. */
	copy = kmemdup(src, len, GFP_KERNEL);
	KUNIT_EXPECT_NOT_NULL(test, copy);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	kfree(copy);

	/* Without %NUL. */
	copy = kmemdup(src, len - 1, GFP_KERNEL);
	KUNIT_EXPECT_NOT_NULL(test, copy);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	kfree(copy);

	/* Tiny bounds. */
	copy = kmemdup(src, 1, GFP_KERNEL);
	KUNIT_EXPECT_NOT_NULL(test, copy);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 0);
	kfree(copy);

	/* Out of bounds by 1 byte. */
	copy = kmemdup(src, len + 1, GFP_KERNEL);
	KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 1);
	kfree(copy);

	/* Way out of bounds. */
	copy = kmemdup(src, len * 2, GFP_KERNEL);
	KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 2);
	kfree(copy);

	/* Starting offset causing out of bounds. */
	copy = kmemdup(src + 1, len, GFP_KERNEL);
	KUNIT_EXPECT_PTR_EQ(test, copy, ZERO_SIZE_PTR);
	KUNIT_EXPECT_EQ(test, fortify_read_overflows, 3);
	kfree(copy);
}

static int fortify_test_init(struct kunit *test)
{
	if (!IS_ENABLED(CONFIG_FORTIFY_SOURCE))
		kunit_skip(test, "Not built with CONFIG_FORTIFY_SOURCE=y");

	fortify_read_overflows = 0;
	kunit_add_named_resource(test, NULL, NULL, &read_resource,
				 "fortify_read_overflows",
				 &fortify_read_overflows);
	fortify_write_overflows = 0;
	kunit_add_named_resource(test, NULL, NULL, &write_resource,
				 "fortify_write_overflows",
				 &fortify_write_overflows);
	return 0;
}

static struct kunit_case fortify_test_cases[] = {
	KUNIT_CASE(known_sizes_test),
	KUNIT_CASE(control_flow_split_test),
	KUNIT_CASE(alloc_size_kmalloc_const_test),
	KUNIT_CASE(alloc_size_kmalloc_dynamic_test),
	KUNIT_CASE(alloc_size_vmalloc_const_test),
	KUNIT_CASE(alloc_size_vmalloc_dynamic_test),
	KUNIT_CASE(alloc_size_kvmalloc_const_test),
	KUNIT_CASE(alloc_size_kvmalloc_dynamic_test),
	KUNIT_CASE(alloc_size_devm_kmalloc_const_test),
	KUNIT_CASE(alloc_size_devm_kmalloc_dynamic_test),
	KUNIT_CASE(strlen_test),
	KUNIT_CASE(strnlen_test),
	KUNIT_CASE(strcpy_test),
	KUNIT_CASE(strncpy_test),
	KUNIT_CASE(strscpy_test),
	KUNIT_CASE(strcat_test),
	KUNIT_CASE(strncat_test),
	KUNIT_CASE(strlcat_test),
	/* skip memset: performs bounds checking on whole structs */
	/* skip memcpy: still using warn-and-overwrite instead of hard-fail */
	KUNIT_CASE(memscan_test),
	KUNIT_CASE(memchr_test),
	KUNIT_CASE(memchr_inv_test),
	KUNIT_CASE(memcmp_test),
	KUNIT_CASE(kmemdup_test),
	{}
};

static struct kunit_suite fortify_test_suite = {
	.name = "fortify",
	.init = fortify_test_init,
	.test_cases = fortify_test_cases,
};

kunit_test_suite(fortify_test_suite);

MODULE_LICENSE("GPL");