xref: /linux/drivers/misc/lkdtm/bugs.c (revision 7f71507851fc7764b36a3221839607d3a45c2025)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * This is for all the tests related to logic bugs (e.g. bad dereferences,
4  * bad alignment, bad loops, bad locking, bad scheduling, deep stacks, and
5  * lockups) along with other things that don't fit well into existing LKDTM
6  * test source files.
7  */
8 #include "lkdtm.h"
9 #include <linux/cpu.h>
10 #include <linux/list.h>
11 #include <linux/sched.h>
12 #include <linux/sched/signal.h>
13 #include <linux/sched/task_stack.h>
14 #include <linux/slab.h>
15 #include <linux/stop_machine.h>
16 #include <linux/uaccess.h>
17 
18 #if IS_ENABLED(CONFIG_X86_32) && !IS_ENABLED(CONFIG_UML)
19 #include <asm/desc.h>
20 #endif
21 
22 struct lkdtm_list {
23 	struct list_head node;
24 };
25 
26 /*
27  * Make sure our attempts to over run the kernel stack doesn't trigger
28  * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
29  * recurse past the end of THREAD_SIZE by default.
30  */
31 #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
32 #define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2)
33 #else
34 #define REC_STACK_SIZE (THREAD_SIZE / 8UL)
35 #endif
36 #define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
37 
38 static int recur_count = REC_NUM_DEFAULT;
39 
40 static DEFINE_SPINLOCK(lock_me_up);
41 
42 /*
43  * Make sure compiler does not optimize this function or stack frame away:
44  * - function marked noinline
45  * - stack variables are marked volatile
46  * - stack variables are written (memset()) and read (buf[..] passed as arg)
47  * - function may have external effects (memzero_explicit())
48  * - no tail recursion possible
49  */
50 static int noinline recursive_loop(int remaining)
51 {
52 	volatile char buf[REC_STACK_SIZE];
53 	volatile int ret;
54 
55 	memset((void *)buf, remaining & 0xFF, sizeof(buf));
56 	if (!remaining)
57 		ret = 0;
58 	else
59 		ret = recursive_loop((int)buf[remaining % sizeof(buf)] - 1);
60 	memzero_explicit((void *)buf, sizeof(buf));
61 	return ret;
62 }
63 
64 /* If the depth is negative, use the default, otherwise keep parameter. */
65 void __init lkdtm_bugs_init(int *recur_param)
66 {
67 	if (*recur_param < 0)
68 		*recur_param = recur_count;
69 	else
70 		recur_count = *recur_param;
71 }
72 
73 static void lkdtm_PANIC(void)
74 {
75 	panic("dumptest");
76 }
77 
78 static int panic_stop_irqoff_fn(void *arg)
79 {
80 	atomic_t *v = arg;
81 
82 	/*
83 	 * As stop_machine() disables interrupts, all CPUs within this function
84 	 * have interrupts disabled and cannot take a regular IPI.
85 	 *
86 	 * The last CPU which enters here will trigger a panic, and as all CPUs
87 	 * cannot take a regular IPI, we'll only be able to stop secondaries if
88 	 * smp_send_stop() or crash_smp_send_stop() uses an NMI.
89 	 */
90 	if (atomic_inc_return(v) == num_online_cpus())
91 		panic("panic stop irqoff test");
92 
93 	for (;;)
94 		cpu_relax();
95 }
96 
97 static void lkdtm_PANIC_STOP_IRQOFF(void)
98 {
99 	atomic_t v = ATOMIC_INIT(0);
100 	stop_machine(panic_stop_irqoff_fn, &v, cpu_online_mask);
101 }
102 
103 static void lkdtm_BUG(void)
104 {
105 	BUG();
106 }
107 
108 static int warn_counter;
109 
110 static void lkdtm_WARNING(void)
111 {
112 	WARN_ON(++warn_counter);
113 }
114 
115 static void lkdtm_WARNING_MESSAGE(void)
116 {
117 	WARN(1, "Warning message trigger count: %d\n", ++warn_counter);
118 }
119 
120 static void lkdtm_EXCEPTION(void)
121 {
122 	*((volatile int *) 0) = 0;
123 }
124 
125 static void lkdtm_LOOP(void)
126 {
127 	for (;;)
128 		;
129 }
130 
131 static void lkdtm_EXHAUST_STACK(void)
132 {
133 	pr_info("Calling function with %lu frame size to depth %d ...\n",
134 		REC_STACK_SIZE, recur_count);
135 	recursive_loop(recur_count);
136 	pr_info("FAIL: survived without exhausting stack?!\n");
137 }
138 
139 static noinline void __lkdtm_CORRUPT_STACK(void *stack)
140 {
141 	memset(stack, '\xff', 64);
142 }
143 
144 /* This should trip the stack canary, not corrupt the return address. */
145 static noinline void lkdtm_CORRUPT_STACK(void)
146 {
147 	/* Use default char array length that triggers stack protection. */
148 	char data[8] __aligned(sizeof(void *));
149 
150 	pr_info("Corrupting stack containing char array ...\n");
151 	__lkdtm_CORRUPT_STACK((void *)&data);
152 }
153 
154 /* Same as above but will only get a canary with -fstack-protector-strong */
155 static noinline void lkdtm_CORRUPT_STACK_STRONG(void)
156 {
157 	union {
158 		unsigned short shorts[4];
159 		unsigned long *ptr;
160 	} data __aligned(sizeof(void *));
161 
162 	pr_info("Corrupting stack containing union ...\n");
163 	__lkdtm_CORRUPT_STACK((void *)&data);
164 }
165 
166 static pid_t stack_pid;
167 static unsigned long stack_addr;
168 
169 static void lkdtm_REPORT_STACK(void)
170 {
171 	volatile uintptr_t magic;
172 	pid_t pid = task_pid_nr(current);
173 
174 	if (pid != stack_pid) {
175 		pr_info("Starting stack offset tracking for pid %d\n", pid);
176 		stack_pid = pid;
177 		stack_addr = (uintptr_t)&magic;
178 	}
179 
180 	pr_info("Stack offset: %d\n", (int)(stack_addr - (uintptr_t)&magic));
181 }
182 
183 static pid_t stack_canary_pid;
184 static unsigned long stack_canary;
185 static unsigned long stack_canary_offset;
186 
187 static noinline void __lkdtm_REPORT_STACK_CANARY(void *stack)
188 {
189 	int i = 0;
190 	pid_t pid = task_pid_nr(current);
191 	unsigned long *canary = (unsigned long *)stack;
192 	unsigned long current_offset = 0, init_offset = 0;
193 
194 	/* Do our best to find the canary in a 16 word window ... */
195 	for (i = 1; i < 16; i++) {
196 		canary = (unsigned long *)stack + i;
197 #ifdef CONFIG_STACKPROTECTOR
198 		if (*canary == current->stack_canary)
199 			current_offset = i;
200 		if (*canary == init_task.stack_canary)
201 			init_offset = i;
202 #endif
203 	}
204 
205 	if (current_offset == 0) {
206 		/*
207 		 * If the canary doesn't match what's in the task_struct,
208 		 * we're either using a global canary or the stack frame
209 		 * layout changed.
210 		 */
211 		if (init_offset != 0) {
212 			pr_err("FAIL: global stack canary found at offset %ld (canary for pid %d matches init_task's)!\n",
213 			       init_offset, pid);
214 		} else {
215 			pr_warn("FAIL: did not correctly locate stack canary :(\n");
216 			pr_expected_config(CONFIG_STACKPROTECTOR);
217 		}
218 
219 		return;
220 	} else if (init_offset != 0) {
221 		pr_warn("WARNING: found both current and init_task canaries nearby?!\n");
222 	}
223 
224 	canary = (unsigned long *)stack + current_offset;
225 	if (stack_canary_pid == 0) {
226 		stack_canary = *canary;
227 		stack_canary_pid = pid;
228 		stack_canary_offset = current_offset;
229 		pr_info("Recorded stack canary for pid %d at offset %ld\n",
230 			stack_canary_pid, stack_canary_offset);
231 	} else if (pid == stack_canary_pid) {
232 		pr_warn("ERROR: saw pid %d again -- please use a new pid\n", pid);
233 	} else {
234 		if (current_offset != stack_canary_offset) {
235 			pr_warn("ERROR: canary offset changed from %ld to %ld!?\n",
236 				stack_canary_offset, current_offset);
237 			return;
238 		}
239 
240 		if (*canary == stack_canary) {
241 			pr_warn("FAIL: canary identical for pid %d and pid %d at offset %ld!\n",
242 				stack_canary_pid, pid, current_offset);
243 		} else {
244 			pr_info("ok: stack canaries differ between pid %d and pid %d at offset %ld.\n",
245 				stack_canary_pid, pid, current_offset);
246 			/* Reset the test. */
247 			stack_canary_pid = 0;
248 		}
249 	}
250 }
251 
252 static void lkdtm_REPORT_STACK_CANARY(void)
253 {
254 	/* Use default char array length that triggers stack protection. */
255 	char data[8] __aligned(sizeof(void *)) = { };
256 
257 	__lkdtm_REPORT_STACK_CANARY((void *)&data);
258 }
259 
260 static void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)
261 {
262 	static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5};
263 	u32 *p;
264 	u32 val = 0x12345678;
265 
266 	p = (u32 *)(data + 1);
267 	if (*p == 0)
268 		val = 0x87654321;
269 	*p = val;
270 
271 	if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
272 		pr_err("XFAIL: arch has CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS\n");
273 }
274 
275 static void lkdtm_SOFTLOCKUP(void)
276 {
277 	preempt_disable();
278 	for (;;)
279 		cpu_relax();
280 }
281 
282 static void lkdtm_HARDLOCKUP(void)
283 {
284 	local_irq_disable();
285 	for (;;)
286 		cpu_relax();
287 }
288 
289 static void __lkdtm_SMP_CALL_LOCKUP(void *unused)
290 {
291 	for (;;)
292 		cpu_relax();
293 }
294 
295 static void lkdtm_SMP_CALL_LOCKUP(void)
296 {
297 	unsigned int cpu, target;
298 
299 	cpus_read_lock();
300 
301 	cpu = get_cpu();
302 	target = cpumask_any_but(cpu_online_mask, cpu);
303 
304 	if (target >= nr_cpu_ids) {
305 		pr_err("FAIL: no other online CPUs\n");
306 		goto out_put_cpus;
307 	}
308 
309 	smp_call_function_single(target, __lkdtm_SMP_CALL_LOCKUP, NULL, 1);
310 
311 	pr_err("FAIL: did not hang\n");
312 
313 out_put_cpus:
314 	put_cpu();
315 	cpus_read_unlock();
316 }
317 
318 static void lkdtm_SPINLOCKUP(void)
319 {
320 	/* Must be called twice to trigger. */
321 	spin_lock(&lock_me_up);
322 	/* Let sparse know we intended to exit holding the lock. */
323 	__release(&lock_me_up);
324 }
325 
326 static void __noreturn lkdtm_HUNG_TASK(void)
327 {
328 	set_current_state(TASK_UNINTERRUPTIBLE);
329 	schedule();
330 	BUG();
331 }
332 
333 static volatile unsigned int huge = INT_MAX - 2;
334 static volatile unsigned int ignored;
335 
336 static void lkdtm_OVERFLOW_SIGNED(void)
337 {
338 	int value;
339 
340 	value = huge;
341 	pr_info("Normal signed addition ...\n");
342 	value += 1;
343 	ignored = value;
344 
345 	pr_info("Overflowing signed addition ...\n");
346 	value += 4;
347 	ignored = value;
348 }
349 
350 
351 static void lkdtm_OVERFLOW_UNSIGNED(void)
352 {
353 	unsigned int value;
354 
355 	value = huge;
356 	pr_info("Normal unsigned addition ...\n");
357 	value += 1;
358 	ignored = value;
359 
360 	pr_info("Overflowing unsigned addition ...\n");
361 	value += 4;
362 	ignored = value;
363 }
364 
365 /* Intentionally using unannotated flex array definition. */
366 struct array_bounds_flex_array {
367 	int one;
368 	int two;
369 	char data[];
370 };
371 
372 struct array_bounds {
373 	int one;
374 	int two;
375 	char data[8];
376 	int three;
377 };
378 
379 static void lkdtm_ARRAY_BOUNDS(void)
380 {
381 	struct array_bounds_flex_array *not_checked;
382 	struct array_bounds *checked;
383 	volatile int i;
384 
385 	not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL);
386 	checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL);
387 	if (!not_checked || !checked) {
388 		kfree(not_checked);
389 		kfree(checked);
390 		return;
391 	}
392 
393 	pr_info("Array access within bounds ...\n");
394 	/* For both, touch all bytes in the actual member size. */
395 	for (i = 0; i < sizeof(checked->data); i++)
396 		checked->data[i] = 'A';
397 	/*
398 	 * For the uninstrumented flex array member, also touch 1 byte
399 	 * beyond to verify it is correctly uninstrumented.
400 	 */
401 	for (i = 0; i < 2; i++)
402 		not_checked->data[i] = 'A';
403 
404 	pr_info("Array access beyond bounds ...\n");
405 	for (i = 0; i < sizeof(checked->data) + 1; i++)
406 		checked->data[i] = 'B';
407 
408 	kfree(not_checked);
409 	kfree(checked);
410 	pr_err("FAIL: survived array bounds overflow!\n");
411 	if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
412 		pr_expected_config(CONFIG_UBSAN_TRAP);
413 	else
414 		pr_expected_config(CONFIG_UBSAN_BOUNDS);
415 }
416 
417 struct lkdtm_annotated {
418 	unsigned long flags;
419 	int count;
420 	int array[] __counted_by(count);
421 };
422 
423 static volatile int fam_count = 4;
424 
425 static void lkdtm_FAM_BOUNDS(void)
426 {
427 	struct lkdtm_annotated *inst;
428 
429 	inst = kzalloc(struct_size(inst, array, fam_count + 1), GFP_KERNEL);
430 	if (!inst) {
431 		pr_err("FAIL: could not allocate test struct!\n");
432 		return;
433 	}
434 
435 	inst->count = fam_count;
436 	pr_info("Array access within bounds ...\n");
437 	inst->array[1] = fam_count;
438 	ignored = inst->array[1];
439 
440 	pr_info("Array access beyond bounds ...\n");
441 	inst->array[fam_count] = fam_count;
442 	ignored = inst->array[fam_count];
443 
444 	kfree(inst);
445 
446 	pr_err("FAIL: survived access of invalid flexible array member index!\n");
447 
448 	if (!IS_ENABLED(CONFIG_CC_HAS_COUNTED_BY))
449 		pr_warn("This is expected since this %s was built with a compiler that does not support __counted_by\n",
450 			lkdtm_kernel_info);
451 	else if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
452 		pr_expected_config(CONFIG_UBSAN_TRAP);
453 	else
454 		pr_expected_config(CONFIG_UBSAN_BOUNDS);
455 }
456 
457 static void lkdtm_CORRUPT_LIST_ADD(void)
458 {
459 	/*
460 	 * Initially, an empty list via LIST_HEAD:
461 	 *	test_head.next = &test_head
462 	 *	test_head.prev = &test_head
463 	 */
464 	LIST_HEAD(test_head);
465 	struct lkdtm_list good, bad;
466 	void *target[2] = { };
467 	void *redirection = &target;
468 
469 	pr_info("attempting good list addition\n");
470 
471 	/*
472 	 * Adding to the list performs these actions:
473 	 *	test_head.next->prev = &good.node
474 	 *	good.node.next = test_head.next
475 	 *	good.node.prev = test_head
476 	 *	test_head.next = good.node
477 	 */
478 	list_add(&good.node, &test_head);
479 
480 	pr_info("attempting corrupted list addition\n");
481 	/*
482 	 * In simulating this "write what where" primitive, the "what" is
483 	 * the address of &bad.node, and the "where" is the address held
484 	 * by "redirection".
485 	 */
486 	test_head.next = redirection;
487 	list_add(&bad.node, &test_head);
488 
489 	if (target[0] == NULL && target[1] == NULL)
490 		pr_err("Overwrite did not happen, but no BUG?!\n");
491 	else {
492 		pr_err("list_add() corruption not detected!\n");
493 		pr_expected_config(CONFIG_LIST_HARDENED);
494 	}
495 }
496 
497 static void lkdtm_CORRUPT_LIST_DEL(void)
498 {
499 	LIST_HEAD(test_head);
500 	struct lkdtm_list item;
501 	void *target[2] = { };
502 	void *redirection = &target;
503 
504 	list_add(&item.node, &test_head);
505 
506 	pr_info("attempting good list removal\n");
507 	list_del(&item.node);
508 
509 	pr_info("attempting corrupted list removal\n");
510 	list_add(&item.node, &test_head);
511 
512 	/* As with the list_add() test above, this corrupts "next". */
513 	item.node.next = redirection;
514 	list_del(&item.node);
515 
516 	if (target[0] == NULL && target[1] == NULL)
517 		pr_err("Overwrite did not happen, but no BUG?!\n");
518 	else {
519 		pr_err("list_del() corruption not detected!\n");
520 		pr_expected_config(CONFIG_LIST_HARDENED);
521 	}
522 }
523 
524 /* Test that VMAP_STACK is actually allocating with a leading guard page */
525 static void lkdtm_STACK_GUARD_PAGE_LEADING(void)
526 {
527 	const unsigned char *stack = task_stack_page(current);
528 	const unsigned char *ptr = stack - 1;
529 	volatile unsigned char byte;
530 
531 	pr_info("attempting bad read from page below current stack\n");
532 
533 	byte = *ptr;
534 
535 	pr_err("FAIL: accessed page before stack! (byte: %x)\n", byte);
536 }
537 
538 /* Test that VMAP_STACK is actually allocating with a trailing guard page */
539 static void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
540 {
541 	const unsigned char *stack = task_stack_page(current);
542 	const unsigned char *ptr = stack + THREAD_SIZE;
543 	volatile unsigned char byte;
544 
545 	pr_info("attempting bad read from page above current stack\n");
546 
547 	byte = *ptr;
548 
549 	pr_err("FAIL: accessed page after stack! (byte: %x)\n", byte);
550 }
551 
552 static void lkdtm_UNSET_SMEP(void)
553 {
554 #if IS_ENABLED(CONFIG_X86_64) && !IS_ENABLED(CONFIG_UML)
555 #define MOV_CR4_DEPTH	64
556 	void (*direct_write_cr4)(unsigned long val);
557 	unsigned char *insn;
558 	unsigned long cr4;
559 	int i;
560 
561 	cr4 = native_read_cr4();
562 
563 	if ((cr4 & X86_CR4_SMEP) != X86_CR4_SMEP) {
564 		pr_err("FAIL: SMEP not in use\n");
565 		return;
566 	}
567 	cr4 &= ~(X86_CR4_SMEP);
568 
569 	pr_info("trying to clear SMEP normally\n");
570 	native_write_cr4(cr4);
571 	if (cr4 == native_read_cr4()) {
572 		pr_err("FAIL: pinning SMEP failed!\n");
573 		cr4 |= X86_CR4_SMEP;
574 		pr_info("restoring SMEP\n");
575 		native_write_cr4(cr4);
576 		return;
577 	}
578 	pr_info("ok: SMEP did not get cleared\n");
579 
580 	/*
581 	 * To test the post-write pinning verification we need to call
582 	 * directly into the middle of native_write_cr4() where the
583 	 * cr4 write happens, skipping any pinning. This searches for
584 	 * the cr4 writing instruction.
585 	 */
586 	insn = (unsigned char *)native_write_cr4;
587 	OPTIMIZER_HIDE_VAR(insn);
588 	for (i = 0; i < MOV_CR4_DEPTH; i++) {
589 		/* mov %rdi, %cr4 */
590 		if (insn[i] == 0x0f && insn[i+1] == 0x22 && insn[i+2] == 0xe7)
591 			break;
592 		/* mov %rdi,%rax; mov %rax, %cr4 */
593 		if (insn[i]   == 0x48 && insn[i+1] == 0x89 &&
594 		    insn[i+2] == 0xf8 && insn[i+3] == 0x0f &&
595 		    insn[i+4] == 0x22 && insn[i+5] == 0xe0)
596 			break;
597 	}
598 	if (i >= MOV_CR4_DEPTH) {
599 		pr_info("ok: cannot locate cr4 writing call gadget\n");
600 		return;
601 	}
602 	direct_write_cr4 = (void *)(insn + i);
603 
604 	pr_info("trying to clear SMEP with call gadget\n");
605 	direct_write_cr4(cr4);
606 	if (native_read_cr4() & X86_CR4_SMEP) {
607 		pr_info("ok: SMEP removal was reverted\n");
608 	} else {
609 		pr_err("FAIL: cleared SMEP not detected!\n");
610 		cr4 |= X86_CR4_SMEP;
611 		pr_info("restoring SMEP\n");
612 		native_write_cr4(cr4);
613 	}
614 #else
615 	pr_err("XFAIL: this test is x86_64-only\n");
616 #endif
617 }
618 
619 static void lkdtm_DOUBLE_FAULT(void)
620 {
621 #if IS_ENABLED(CONFIG_X86_32) && !IS_ENABLED(CONFIG_UML)
622 	/*
623 	 * Trigger #DF by setting the stack limit to zero.  This clobbers
624 	 * a GDT TLS slot, which is okay because the current task will die
625 	 * anyway due to the double fault.
626 	 */
627 	struct desc_struct d = {
628 		.type = 3,	/* expand-up, writable, accessed data */
629 		.p = 1,		/* present */
630 		.d = 1,		/* 32-bit */
631 		.g = 0,		/* limit in bytes */
632 		.s = 1,		/* not system */
633 	};
634 
635 	local_irq_disable();
636 	write_gdt_entry(get_cpu_gdt_rw(smp_processor_id()),
637 			GDT_ENTRY_TLS_MIN, &d, DESCTYPE_S);
638 
639 	/*
640 	 * Put our zero-limit segment in SS and then trigger a fault.  The
641 	 * 4-byte access to (%esp) will fault with #SS, and the attempt to
642 	 * deliver the fault will recursively cause #SS and result in #DF.
643 	 * This whole process happens while NMIs and MCEs are blocked by the
644 	 * MOV SS window.  This is nice because an NMI with an invalid SS
645 	 * would also double-fault, resulting in the NMI or MCE being lost.
646 	 */
647 	asm volatile ("movw %0, %%ss; addl $0, (%%esp)" ::
648 		      "r" ((unsigned short)(GDT_ENTRY_TLS_MIN << 3)));
649 
650 	pr_err("FAIL: tried to double fault but didn't die\n");
651 #else
652 	pr_err("XFAIL: this test is ia32-only\n");
653 #endif
654 }
655 
656 #ifdef CONFIG_ARM64
657 static noinline void change_pac_parameters(void)
658 {
659 	if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) {
660 		/* Reset the keys of current task */
661 		ptrauth_thread_init_kernel(current);
662 		ptrauth_thread_switch_kernel(current);
663 	}
664 }
665 #endif
666 
667 static noinline void lkdtm_CORRUPT_PAC(void)
668 {
669 #ifdef CONFIG_ARM64
670 #define CORRUPT_PAC_ITERATE	10
671 	int i;
672 
673 	if (!IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
674 		pr_err("FAIL: kernel not built with CONFIG_ARM64_PTR_AUTH_KERNEL\n");
675 
676 	if (!system_supports_address_auth()) {
677 		pr_err("FAIL: CPU lacks pointer authentication feature\n");
678 		return;
679 	}
680 
681 	pr_info("changing PAC parameters to force function return failure...\n");
682 	/*
683 	 * PAC is a hash value computed from input keys, return address and
684 	 * stack pointer. As pac has fewer bits so there is a chance of
685 	 * collision, so iterate few times to reduce the collision probability.
686 	 */
687 	for (i = 0; i < CORRUPT_PAC_ITERATE; i++)
688 		change_pac_parameters();
689 
690 	pr_err("FAIL: survived PAC changes! Kernel may be unstable from here\n");
691 #else
692 	pr_err("XFAIL: this test is arm64-only\n");
693 #endif
694 }
695 
696 static struct crashtype crashtypes[] = {
697 	CRASHTYPE(PANIC),
698 	CRASHTYPE(PANIC_STOP_IRQOFF),
699 	CRASHTYPE(BUG),
700 	CRASHTYPE(WARNING),
701 	CRASHTYPE(WARNING_MESSAGE),
702 	CRASHTYPE(EXCEPTION),
703 	CRASHTYPE(LOOP),
704 	CRASHTYPE(EXHAUST_STACK),
705 	CRASHTYPE(CORRUPT_STACK),
706 	CRASHTYPE(CORRUPT_STACK_STRONG),
707 	CRASHTYPE(REPORT_STACK),
708 	CRASHTYPE(REPORT_STACK_CANARY),
709 	CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
710 	CRASHTYPE(SOFTLOCKUP),
711 	CRASHTYPE(HARDLOCKUP),
712 	CRASHTYPE(SMP_CALL_LOCKUP),
713 	CRASHTYPE(SPINLOCKUP),
714 	CRASHTYPE(HUNG_TASK),
715 	CRASHTYPE(OVERFLOW_SIGNED),
716 	CRASHTYPE(OVERFLOW_UNSIGNED),
717 	CRASHTYPE(ARRAY_BOUNDS),
718 	CRASHTYPE(FAM_BOUNDS),
719 	CRASHTYPE(CORRUPT_LIST_ADD),
720 	CRASHTYPE(CORRUPT_LIST_DEL),
721 	CRASHTYPE(STACK_GUARD_PAGE_LEADING),
722 	CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
723 	CRASHTYPE(UNSET_SMEP),
724 	CRASHTYPE(DOUBLE_FAULT),
725 	CRASHTYPE(CORRUPT_PAC),
726 };
727 
728 struct crashtype_category bugs_crashtypes = {
729 	.crashtypes = crashtypes,
730 	.len	    = ARRAY_SIZE(crashtypes),
731 };
732