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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Test cases for KFENCE memory safety error detector. Since the interface with
4 * which KFENCE's reports are obtained is via the console, this is the output we
5 * should verify. For each test case checks the presence (or absence) of
6 * generated reports. Relies on 'console' tracepoint to capture reports as they
7 * appear in the kernel log.
8 *
9 * Copyright (C) 2020, Google LLC.
10 * Author: Alexander Potapenko <glider@google.com>
11 * Marco Elver <elver@google.com>
12 */
13
14#include <kunit/test.h>
15#include <linux/jiffies.h>
16#include <linux/kernel.h>
17#include <linux/kfence.h>
18#include <linux/mm.h>
19#include <linux/random.h>
20#include <linux/slab.h>
21#include <linux/spinlock.h>
22#include <linux/string.h>
23#include <linux/tracepoint.h>
24#include <trace/events/printk.h>
25
26#include <asm/kfence.h>
27
28#include "kfence.h"
29
30/* May be overridden by <asm/kfence.h>. */
31#ifndef arch_kfence_test_address
32#define arch_kfence_test_address(addr) (addr)
33#endif
34
35#define KFENCE_TEST_REQUIRES(test, cond) do { \
36 if (!(cond)) \
37 kunit_skip((test), "Test requires: " #cond); \
38} while (0)
39
40/* Report as observed from console. */
41static struct {
42 spinlock_t lock;
43 int nlines;
44 char lines[2][256];
45} observed = {
46 .lock = __SPIN_LOCK_UNLOCKED(observed.lock),
47};
48
49/* Probe for console output: obtains observed lines of interest. */
50static void probe_console(void *ignore, const char *buf, size_t len)
51{
52 unsigned long flags;
53 int nlines;
54
55 spin_lock_irqsave(&observed.lock, flags);
56 nlines = observed.nlines;
57
58 if (strnstr(buf, "BUG: KFENCE: ", len) && strnstr(buf, "test_", len)) {
59 /*
60 * KFENCE report and related to the test.
61 *
62 * The provided @buf is not NUL-terminated; copy no more than
63 * @len bytes and let strscpy() add the missing NUL-terminator.
64 */
65 strscpy(observed.lines[0], buf, min(len + 1, sizeof(observed.lines[0])));
66 nlines = 1;
67 } else if (nlines == 1 && (strnstr(buf, "at 0x", len) || strnstr(buf, "of 0x", len))) {
68 strscpy(observed.lines[nlines++], buf, min(len + 1, sizeof(observed.lines[0])));
69 }
70
71 WRITE_ONCE(observed.nlines, nlines); /* Publish new nlines. */
72 spin_unlock_irqrestore(&observed.lock, flags);
73}
74
75/* Check if a report related to the test exists. */
76static bool report_available(void)
77{
78 return READ_ONCE(observed.nlines) == ARRAY_SIZE(observed.lines);
79}
80
81/* Information we expect in a report. */
82struct expect_report {
83 enum kfence_error_type type; /* The type or error. */
84 void *fn; /* Function pointer to expected function where access occurred. */
85 char *addr; /* Address at which the bad access occurred. */
86 bool is_write; /* Is access a write. */
87};
88
89static const char *get_access_type(const struct expect_report *r)
90{
91 return r->is_write ? "write" : "read";
92}
93
94/* Check observed report matches information in @r. */
95static bool report_matches(const struct expect_report *r)
96{
97 unsigned long addr = (unsigned long)r->addr;
98 bool ret = false;
99 unsigned long flags;
100 typeof(observed.lines) expect;
101 const char *end;
102 char *cur;
103
104 /* Doubled-checked locking. */
105 if (!report_available())
106 return false;
107
108 /* Generate expected report contents. */
109
110 /* Title */
111 cur = expect[0];
112 end = &expect[0][sizeof(expect[0]) - 1];
113 switch (r->type) {
114 case KFENCE_ERROR_OOB:
115 cur += scnprintf(cur, end - cur, "BUG: KFENCE: out-of-bounds %s",
116 get_access_type(r));
117 break;
118 case KFENCE_ERROR_UAF:
119 cur += scnprintf(cur, end - cur, "BUG: KFENCE: use-after-free %s",
120 get_access_type(r));
121 break;
122 case KFENCE_ERROR_CORRUPTION:
123 cur += scnprintf(cur, end - cur, "BUG: KFENCE: memory corruption");
124 break;
125 case KFENCE_ERROR_INVALID:
126 cur += scnprintf(cur, end - cur, "BUG: KFENCE: invalid %s",
127 get_access_type(r));
128 break;
129 case KFENCE_ERROR_INVALID_FREE:
130 cur += scnprintf(cur, end - cur, "BUG: KFENCE: invalid free");
131 break;
132 }
133
134 scnprintf(cur, end - cur, " in %pS", r->fn);
135 /* The exact offset won't match, remove it; also strip module name. */
136 cur = strchr(expect[0], '+');
137 if (cur)
138 *cur = '\0';
139
140 /* Access information */
141 cur = expect[1];
142 end = &expect[1][sizeof(expect[1]) - 1];
143
144 switch (r->type) {
145 case KFENCE_ERROR_OOB:
146 cur += scnprintf(cur, end - cur, "Out-of-bounds %s at", get_access_type(r));
147 addr = arch_kfence_test_address(addr);
148 break;
149 case KFENCE_ERROR_UAF:
150 cur += scnprintf(cur, end - cur, "Use-after-free %s at", get_access_type(r));
151 addr = arch_kfence_test_address(addr);
152 break;
153 case KFENCE_ERROR_CORRUPTION:
154 cur += scnprintf(cur, end - cur, "Corrupted memory at");
155 break;
156 case KFENCE_ERROR_INVALID:
157 cur += scnprintf(cur, end - cur, "Invalid %s at", get_access_type(r));
158 addr = arch_kfence_test_address(addr);
159 break;
160 case KFENCE_ERROR_INVALID_FREE:
161 cur += scnprintf(cur, end - cur, "Invalid free of");
162 break;
163 }
164
165 cur += scnprintf(cur, end - cur, " 0x%p", (void *)addr);
166
167 spin_lock_irqsave(&observed.lock, flags);
168 if (!report_available())
169 goto out; /* A new report is being captured. */
170
171 /* Finally match expected output to what we actually observed. */
172 ret = strstr(observed.lines[0], expect[0]) && strstr(observed.lines[1], expect[1]);
173out:
174 spin_unlock_irqrestore(&observed.lock, flags);
175 return ret;
176}
177
178/* ===== Test cases ===== */
179
180#define TEST_PRIV_WANT_MEMCACHE ((void *)1)
181
182/* Cache used by tests; if NULL, allocate from kmalloc instead. */
183static struct kmem_cache *test_cache;
184
185static size_t setup_test_cache(struct kunit *test, size_t size, slab_flags_t flags,
186 void (*ctor)(void *))
187{
188 if (test->priv != TEST_PRIV_WANT_MEMCACHE)
189 return size;
190
191 kunit_info(test, "%s: size=%zu, ctor=%ps\n", __func__, size, ctor);
192
193 /*
194 * Use SLAB_NO_MERGE to prevent merging with existing caches.
195 * Use SLAB_ACCOUNT to allocate via memcg, if enabled.
196 */
197 flags |= SLAB_NO_MERGE | SLAB_ACCOUNT;
198 test_cache = kmem_cache_create("test", size, 1, flags, ctor);
199 KUNIT_ASSERT_TRUE_MSG(test, test_cache, "could not create cache");
200
201 return size;
202}
203
204static void test_cache_destroy(void)
205{
206 if (!test_cache)
207 return;
208
209 kmem_cache_destroy(test_cache);
210 test_cache = NULL;
211}
212
213static inline size_t kmalloc_cache_alignment(size_t size)
214{
215 /* just to get ->align so no need to pass in the real caller */
216 enum kmalloc_cache_type type = kmalloc_type(GFP_KERNEL, 0);
217 return kmalloc_caches[type][__kmalloc_index(size, false)]->align;
218}
219
220/* Must always inline to match stack trace against caller. */
221static __always_inline void test_free(void *ptr)
222{
223 if (test_cache)
224 kmem_cache_free(test_cache, ptr);
225 else
226 kfree(ptr);
227}
228
229/*
230 * If this should be a KFENCE allocation, and on which side the allocation and
231 * the closest guard page should be.
232 */
233enum allocation_policy {
234 ALLOCATE_ANY, /* KFENCE, any side. */
235 ALLOCATE_LEFT, /* KFENCE, left side of page. */
236 ALLOCATE_RIGHT, /* KFENCE, right side of page. */
237 ALLOCATE_NONE, /* No KFENCE allocation. */
238};
239
240/*
241 * Try to get a guarded allocation from KFENCE. Uses either kmalloc() or the
242 * current test_cache if set up.
243 */
244static void *test_alloc(struct kunit *test, size_t size, gfp_t gfp, enum allocation_policy policy)
245{
246 void *alloc;
247 unsigned long timeout, resched_after;
248 const char *policy_name;
249
250 switch (policy) {
251 case ALLOCATE_ANY:
252 policy_name = "any";
253 break;
254 case ALLOCATE_LEFT:
255 policy_name = "left";
256 break;
257 case ALLOCATE_RIGHT:
258 policy_name = "right";
259 break;
260 case ALLOCATE_NONE:
261 policy_name = "none";
262 break;
263 }
264
265 kunit_info(test, "%s: size=%zu, gfp=%x, policy=%s, cache=%i\n", __func__, size, gfp,
266 policy_name, !!test_cache);
267
268 /*
269 * 100x the sample interval should be more than enough to ensure we get
270 * a KFENCE allocation eventually.
271 */
272 timeout = jiffies + msecs_to_jiffies(100 * kfence_sample_interval);
273 /*
274 * Especially for non-preemption kernels, ensure the allocation-gate
275 * timer can catch up: after @resched_after, every failed allocation
276 * attempt yields, to ensure the allocation-gate timer is scheduled.
277 */
278 resched_after = jiffies + msecs_to_jiffies(kfence_sample_interval);
279 do {
280 if (test_cache)
281 alloc = kmem_cache_alloc(test_cache, gfp);
282 else
283 alloc = kmalloc(size, gfp);
284
285 if (is_kfence_address(alloc)) {
286 struct slab *slab = virt_to_slab(alloc);
287 enum kmalloc_cache_type type = kmalloc_type(GFP_KERNEL, _RET_IP_);
288 struct kmem_cache *s = test_cache ?:
289 kmalloc_caches[type][__kmalloc_index(size, false)];
290
291 /*
292 * Verify that various helpers return the right values
293 * even for KFENCE objects; these are required so that
294 * memcg accounting works correctly.
295 */
296 KUNIT_EXPECT_EQ(test, obj_to_index(s, slab, alloc), 0U);
297 KUNIT_EXPECT_EQ(test, objs_per_slab(s, slab), 1);
298
299 if (policy == ALLOCATE_ANY)
300 return alloc;
301 if (policy == ALLOCATE_LEFT && PAGE_ALIGNED(alloc))
302 return alloc;
303 if (policy == ALLOCATE_RIGHT && !PAGE_ALIGNED(alloc))
304 return alloc;
305 } else if (policy == ALLOCATE_NONE)
306 return alloc;
307
308 test_free(alloc);
309
310 if (time_after(jiffies, resched_after))
311 cond_resched();
312 } while (time_before(jiffies, timeout));
313
314 KUNIT_ASSERT_TRUE_MSG(test, false, "failed to allocate from KFENCE");
315 return NULL; /* Unreachable. */
316}
317
318static void test_out_of_bounds_read(struct kunit *test)
319{
320 size_t size = 32;
321 struct expect_report expect = {
322 .type = KFENCE_ERROR_OOB,
323 .fn = test_out_of_bounds_read,
324 .is_write = false,
325 };
326 char *buf;
327
328 setup_test_cache(test, size, 0, NULL);
329
330 /*
331 * If we don't have our own cache, adjust based on alignment, so that we
332 * actually access guard pages on either side.
333 */
334 if (!test_cache)
335 size = kmalloc_cache_alignment(size);
336
337 /* Test both sides. */
338
339 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_LEFT);
340 expect.addr = buf - 1;
341 READ_ONCE(*expect.addr);
342 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
343 test_free(buf);
344
345 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT);
346 expect.addr = buf + size;
347 READ_ONCE(*expect.addr);
348 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
349 test_free(buf);
350}
351
352static void test_out_of_bounds_write(struct kunit *test)
353{
354 size_t size = 32;
355 struct expect_report expect = {
356 .type = KFENCE_ERROR_OOB,
357 .fn = test_out_of_bounds_write,
358 .is_write = true,
359 };
360 char *buf;
361
362 setup_test_cache(test, size, 0, NULL);
363 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_LEFT);
364 expect.addr = buf - 1;
365 WRITE_ONCE(*expect.addr, 42);
366 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
367 test_free(buf);
368}
369
370static void test_use_after_free_read(struct kunit *test)
371{
372 const size_t size = 32;
373 struct expect_report expect = {
374 .type = KFENCE_ERROR_UAF,
375 .fn = test_use_after_free_read,
376 .is_write = false,
377 };
378
379 setup_test_cache(test, size, 0, NULL);
380 expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
381 test_free(expect.addr);
382 READ_ONCE(*expect.addr);
383 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
384}
385
386static void test_use_after_free_read_nofault(struct kunit *test)
387{
388 const size_t size = 32;
389 char *addr;
390 char dst;
391 int ret;
392
393 setup_test_cache(test, size, 0, NULL);
394 addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
395 test_free(addr);
396 /* Use after free with *_nofault() */
397 ret = copy_from_kernel_nofault(&dst, addr, 1);
398 KUNIT_EXPECT_EQ(test, ret, -EFAULT);
399 KUNIT_EXPECT_FALSE(test, report_available());
400}
401
402static void test_double_free(struct kunit *test)
403{
404 const size_t size = 32;
405 struct expect_report expect = {
406 .type = KFENCE_ERROR_INVALID_FREE,
407 .fn = test_double_free,
408 };
409
410 setup_test_cache(test, size, 0, NULL);
411 expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
412 test_free(expect.addr);
413 test_free(expect.addr); /* Double-free. */
414 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
415}
416
417static void test_invalid_addr_free(struct kunit *test)
418{
419 const size_t size = 32;
420 struct expect_report expect = {
421 .type = KFENCE_ERROR_INVALID_FREE,
422 .fn = test_invalid_addr_free,
423 };
424 char *buf;
425
426 setup_test_cache(test, size, 0, NULL);
427 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
428 expect.addr = buf + 1; /* Free on invalid address. */
429 test_free(expect.addr); /* Invalid address free. */
430 test_free(buf); /* No error. */
431 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
432}
433
434static void test_corruption(struct kunit *test)
435{
436 size_t size = 32;
437 struct expect_report expect = {
438 .type = KFENCE_ERROR_CORRUPTION,
439 .fn = test_corruption,
440 };
441 char *buf;
442
443 setup_test_cache(test, size, 0, NULL);
444
445 /* Test both sides. */
446
447 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_LEFT);
448 expect.addr = buf + size;
449 WRITE_ONCE(*expect.addr, 42);
450 test_free(buf);
451 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
452
453 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT);
454 expect.addr = buf - 1;
455 WRITE_ONCE(*expect.addr, 42);
456 test_free(buf);
457 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
458}
459
460/*
461 * KFENCE is unable to detect an OOB if the allocation's alignment requirements
462 * leave a gap between the object and the guard page. Specifically, an
463 * allocation of e.g. 73 bytes is aligned on 8 and 128 bytes for SLUB or SLAB
464 * respectively. Therefore it is impossible for the allocated object to
465 * contiguously line up with the right guard page.
466 *
467 * However, we test that an access to memory beyond the gap results in KFENCE
468 * detecting an OOB access.
469 */
470static void test_kmalloc_aligned_oob_read(struct kunit *test)
471{
472 const size_t size = 73;
473 const size_t align = kmalloc_cache_alignment(size);
474 struct expect_report expect = {
475 .type = KFENCE_ERROR_OOB,
476 .fn = test_kmalloc_aligned_oob_read,
477 .is_write = false,
478 };
479 char *buf;
480
481 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT);
482
483 /*
484 * The object is offset to the right, so there won't be an OOB to the
485 * left of it.
486 */
487 READ_ONCE(*(buf - 1));
488 KUNIT_EXPECT_FALSE(test, report_available());
489
490 /*
491 * @buf must be aligned on @align, therefore buf + size belongs to the
492 * same page -> no OOB.
493 */
494 READ_ONCE(*(buf + size));
495 KUNIT_EXPECT_FALSE(test, report_available());
496
497 /* Overflowing by @align bytes will result in an OOB. */
498 expect.addr = buf + size + align;
499 READ_ONCE(*expect.addr);
500 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
501
502 test_free(buf);
503}
504
505static void test_kmalloc_aligned_oob_write(struct kunit *test)
506{
507 const size_t size = 73;
508 struct expect_report expect = {
509 .type = KFENCE_ERROR_CORRUPTION,
510 .fn = test_kmalloc_aligned_oob_write,
511 };
512 char *buf;
513
514 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT);
515 /*
516 * The object is offset to the right, so we won't get a page
517 * fault immediately after it.
518 */
519 expect.addr = buf + size;
520 WRITE_ONCE(*expect.addr, READ_ONCE(*expect.addr) + 1);
521 KUNIT_EXPECT_FALSE(test, report_available());
522 test_free(buf);
523 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
524}
525
526/* Test cache shrinking and destroying with KFENCE. */
527static void test_shrink_memcache(struct kunit *test)
528{
529 const size_t size = 32;
530 void *buf;
531
532 setup_test_cache(test, size, 0, NULL);
533 KUNIT_EXPECT_TRUE(test, test_cache);
534 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
535 kmem_cache_shrink(test_cache);
536 test_free(buf);
537
538 KUNIT_EXPECT_FALSE(test, report_available());
539}
540
541static void ctor_set_x(void *obj)
542{
543 /* Every object has at least 8 bytes. */
544 memset(obj, 'x', 8);
545}
546
547/* Ensure that SL*B does not modify KFENCE objects on bulk free. */
548static void test_free_bulk(struct kunit *test)
549{
550 int iter;
551
552 for (iter = 0; iter < 5; iter++) {
553 const size_t size = setup_test_cache(test, get_random_u32_inclusive(8, 307),
554 0, (iter & 1) ? ctor_set_x : NULL);
555 void *objects[] = {
556 test_alloc(test, size, GFP_KERNEL, ALLOCATE_RIGHT),
557 test_alloc(test, size, GFP_KERNEL, ALLOCATE_NONE),
558 test_alloc(test, size, GFP_KERNEL, ALLOCATE_LEFT),
559 test_alloc(test, size, GFP_KERNEL, ALLOCATE_NONE),
560 test_alloc(test, size, GFP_KERNEL, ALLOCATE_NONE),
561 };
562
563 kmem_cache_free_bulk(test_cache, ARRAY_SIZE(objects), objects);
564 KUNIT_ASSERT_FALSE(test, report_available());
565 test_cache_destroy();
566 }
567}
568
569/* Test init-on-free works. */
570static void test_init_on_free(struct kunit *test)
571{
572 const size_t size = 32;
573 struct expect_report expect = {
574 .type = KFENCE_ERROR_UAF,
575 .fn = test_init_on_free,
576 .is_write = false,
577 };
578 int i;
579
580 KFENCE_TEST_REQUIRES(test, IS_ENABLED(CONFIG_INIT_ON_FREE_DEFAULT_ON));
581 /* Assume it hasn't been disabled on command line. */
582
583 setup_test_cache(test, size, 0, NULL);
584 expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
585 for (i = 0; i < size; i++)
586 expect.addr[i] = i + 1;
587 test_free(expect.addr);
588
589 for (i = 0; i < size; i++) {
590 /*
591 * This may fail if the page was recycled by KFENCE and then
592 * written to again -- this however, is near impossible with a
593 * default config.
594 */
595 KUNIT_EXPECT_EQ(test, expect.addr[i], (char)0);
596
597 if (!i) /* Only check first access to not fail test if page is ever re-protected. */
598 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
599 }
600}
601
602/* Ensure that constructors work properly. */
603static void test_memcache_ctor(struct kunit *test)
604{
605 const size_t size = 32;
606 char *buf;
607 int i;
608
609 setup_test_cache(test, size, 0, ctor_set_x);
610 buf = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
611
612 for (i = 0; i < 8; i++)
613 KUNIT_EXPECT_EQ(test, buf[i], (char)'x');
614
615 test_free(buf);
616
617 KUNIT_EXPECT_FALSE(test, report_available());
618}
619
620/* Test that memory is zeroed if requested. */
621static void test_gfpzero(struct kunit *test)
622{
623 const size_t size = PAGE_SIZE; /* PAGE_SIZE so we can use ALLOCATE_ANY. */
624 char *buf1, *buf2;
625 int i;
626
627 /* Skip if we think it'd take too long. */
628 KFENCE_TEST_REQUIRES(test, kfence_sample_interval <= 100);
629
630 setup_test_cache(test, size, 0, NULL);
631 buf1 = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
632 for (i = 0; i < size; i++)
633 buf1[i] = i + 1;
634 test_free(buf1);
635
636 /* Try to get same address again -- this can take a while. */
637 for (i = 0;; i++) {
638 buf2 = test_alloc(test, size, GFP_KERNEL | __GFP_ZERO, ALLOCATE_ANY);
639 if (buf1 == buf2)
640 break;
641 test_free(buf2);
642
643 if (kthread_should_stop() || (i == CONFIG_KFENCE_NUM_OBJECTS)) {
644 kunit_warn(test, "giving up ... cannot get same object back\n");
645 return;
646 }
647 cond_resched();
648 }
649
650 for (i = 0; i < size; i++)
651 KUNIT_EXPECT_EQ(test, buf2[i], (char)0);
652
653 test_free(buf2);
654
655 KUNIT_EXPECT_FALSE(test, report_available());
656}
657
658static void test_invalid_access(struct kunit *test)
659{
660 const struct expect_report expect = {
661 .type = KFENCE_ERROR_INVALID,
662 .fn = test_invalid_access,
663 .addr = &__kfence_pool[10],
664 .is_write = false,
665 };
666
667 READ_ONCE(__kfence_pool[10]);
668 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
669}
670
671/* Test SLAB_TYPESAFE_BY_RCU works. */
672static void test_memcache_typesafe_by_rcu(struct kunit *test)
673{
674 const size_t size = 32;
675 struct expect_report expect = {
676 .type = KFENCE_ERROR_UAF,
677 .fn = test_memcache_typesafe_by_rcu,
678 .is_write = false,
679 };
680
681 setup_test_cache(test, size, SLAB_TYPESAFE_BY_RCU, NULL);
682 KUNIT_EXPECT_TRUE(test, test_cache); /* Want memcache. */
683
684 expect.addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY);
685 *expect.addr = 42;
686
687 rcu_read_lock();
688 test_free(expect.addr);
689 KUNIT_EXPECT_EQ(test, *expect.addr, (char)42);
690 /*
691 * Up to this point, memory should not have been freed yet, and
692 * therefore there should be no KFENCE report from the above access.
693 */
694 rcu_read_unlock();
695
696 /* Above access to @expect.addr should not have generated a report! */
697 KUNIT_EXPECT_FALSE(test, report_available());
698
699 /* Only after rcu_barrier() is the memory guaranteed to be freed. */
700 rcu_barrier();
701
702 /* Expect use-after-free. */
703 KUNIT_EXPECT_EQ(test, *expect.addr, (char)42);
704 KUNIT_EXPECT_TRUE(test, report_matches(&expect));
705}
706
707/* Test krealloc(). */
708static void test_krealloc(struct kunit *test)
709{
710 const size_t size = 32;
711 const struct expect_report expect = {
712 .type = KFENCE_ERROR_UAF,
713 .fn = test_krealloc,
714 .addr = test_alloc(test, size, GFP_KERNEL, ALLOCATE_ANY),
715 .is_write = false,
716 };
717 char *buf = expect.addr;
718 int i;
719
720 KUNIT_EXPECT_FALSE(test, test_cache);
721 KUNIT_EXPECT_EQ(test, ksize(buf), size); /* Precise size match after KFENCE alloc. */
722 for (i = 0; i < size; i++)
723 buf[i] = i + 1;
724
725 /* Check that we successfully change the size. */
726 buf = krealloc(buf, size * 3, GFP_KERNEL); /* Grow. */
727 /* Note: Might no longer be a KFENCE alloc. */
728 KUNIT_EXPECT_GE(test, ksize(buf), size * 3);
729 for (i = 0; i < size; i++)
730 KUNIT_EXPECT_EQ(test, buf[i], (char)(i + 1));
731 for (; i < size * 3; i++) /* Fill to extra bytes. */
732 buf[i] = i + 1;
733
734 buf = krealloc(buf, size * 2, GFP_KERNEL); /* Shrink. */
735 KUNIT_EXPECT_GE(test, ksize(buf), size * 2);
736 for (i = 0; i < size * 2; i++)
737 KUNIT_EXPECT_EQ(test, buf[i], (char)(i + 1));
738
739 buf = krealloc(buf, 0, GFP_KERNEL); /* Free. */
740 KUNIT_EXPECT_EQ(test, (unsigned long)buf, (unsigned long)ZERO_SIZE_PTR);
741 KUNIT_ASSERT_FALSE(test, report_available()); /* No reports yet! */
742
743 READ_ONCE(*expect.addr); /* Ensure krealloc() actually freed earlier KFENCE object. */
744 KUNIT_ASSERT_TRUE(test, report_matches(&expect));
745}
746
747/* Test that some objects from a bulk allocation belong to KFENCE pool. */
748static void test_memcache_alloc_bulk(struct kunit *test)
749{
750 const size_t size = 32;
751 bool pass = false;
752 unsigned long timeout;
753
754 setup_test_cache(test, size, 0, NULL);
755 KUNIT_EXPECT_TRUE(test, test_cache); /* Want memcache. */
756 /*
757 * 100x the sample interval should be more than enough to ensure we get
758 * a KFENCE allocation eventually.
759 */
760 timeout = jiffies + msecs_to_jiffies(100 * kfence_sample_interval);
761 do {
762 void *objects[100];
763 int i, num = kmem_cache_alloc_bulk(test_cache, GFP_ATOMIC, ARRAY_SIZE(objects),
764 objects);
765 if (!num)
766 continue;
767 for (i = 0; i < ARRAY_SIZE(objects); i++) {
768 if (is_kfence_address(objects[i])) {
769 pass = true;
770 break;
771 }
772 }
773 kmem_cache_free_bulk(test_cache, num, objects);
774 /*
775 * kmem_cache_alloc_bulk() disables interrupts, and calling it
776 * in a tight loop may not give KFENCE a chance to switch the
777 * static branch. Call cond_resched() to let KFENCE chime in.
778 */
779 cond_resched();
780 } while (!pass && time_before(jiffies, timeout));
781
782 KUNIT_EXPECT_TRUE(test, pass);
783 KUNIT_EXPECT_FALSE(test, report_available());
784}
785
786/*
787 * KUnit does not provide a way to provide arguments to tests, and we encode
788 * additional info in the name. Set up 2 tests per test case, one using the
789 * default allocator, and another using a custom memcache (suffix '-memcache').
790 */
791#define KFENCE_KUNIT_CASE(test_name) \
792 { .run_case = test_name, .name = #test_name }, \
793 { .run_case = test_name, .name = #test_name "-memcache" }
794
795static struct kunit_case kfence_test_cases[] = {
796 KFENCE_KUNIT_CASE(test_out_of_bounds_read),
797 KFENCE_KUNIT_CASE(test_out_of_bounds_write),
798 KFENCE_KUNIT_CASE(test_use_after_free_read),
799 KFENCE_KUNIT_CASE(test_use_after_free_read_nofault),
800 KFENCE_KUNIT_CASE(test_double_free),
801 KFENCE_KUNIT_CASE(test_invalid_addr_free),
802 KFENCE_KUNIT_CASE(test_corruption),
803 KFENCE_KUNIT_CASE(test_free_bulk),
804 KFENCE_KUNIT_CASE(test_init_on_free),
805 KUNIT_CASE(test_kmalloc_aligned_oob_read),
806 KUNIT_CASE(test_kmalloc_aligned_oob_write),
807 KUNIT_CASE(test_shrink_memcache),
808 KUNIT_CASE(test_memcache_ctor),
809 KUNIT_CASE(test_invalid_access),
810 KUNIT_CASE(test_gfpzero),
811 KUNIT_CASE(test_memcache_typesafe_by_rcu),
812 KUNIT_CASE(test_krealloc),
813 KUNIT_CASE(test_memcache_alloc_bulk),
814 {},
815};
816
817/* ===== End test cases ===== */
818
819static int test_init(struct kunit *test)
820{
821 unsigned long flags;
822 int i;
823
824 if (!__kfence_pool)
825 return -EINVAL;
826
827 spin_lock_irqsave(&observed.lock, flags);
828 for (i = 0; i < ARRAY_SIZE(observed.lines); i++)
829 observed.lines[i][0] = '\0';
830 observed.nlines = 0;
831 spin_unlock_irqrestore(&observed.lock, flags);
832
833 /* Any test with 'memcache' in its name will want a memcache. */
834 if (strstr(test->name, "memcache"))
835 test->priv = TEST_PRIV_WANT_MEMCACHE;
836 else
837 test->priv = NULL;
838
839 return 0;
840}
841
842static void test_exit(struct kunit *test)
843{
844 test_cache_destroy();
845}
846
847static int kfence_suite_init(struct kunit_suite *suite)
848{
849 register_trace_console(probe_console, NULL);
850 return 0;
851}
852
853static void kfence_suite_exit(struct kunit_suite *suite)
854{
855 unregister_trace_console(probe_console, NULL);
856 tracepoint_synchronize_unregister();
857}
858
859static struct kunit_suite kfence_test_suite = {
860 .name = "kfence",
861 .test_cases = kfence_test_cases,
862 .init = test_init,
863 .exit = test_exit,
864 .suite_init = kfence_suite_init,
865 .suite_exit = kfence_suite_exit,
866};
867
868kunit_test_suites(&kfence_test_suite);
869
870MODULE_LICENSE("GPL v2");
871MODULE_AUTHOR("Alexander Potapenko <glider@google.com>, Marco Elver <elver@google.com>");
872MODULE_DESCRIPTION("kfence unit test suite");