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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/efi.h>
11#include <linux/list.h>
12#include <linux/hrtimer.h>
13#include <linux/sched.h>
14#include <linux/sched/signal.h>
15#include <linux/sched/task_stack.h>
16#include <linux/slab.h>
17#include <linux/stop_machine.h>
18#include <linux/uaccess.h>
19
20#if IS_ENABLED(CONFIG_X86_32) && !IS_ENABLED(CONFIG_UML)
21#include <asm/desc.h>
22#endif
23
24struct lkdtm_list {
25 struct list_head node;
26};
27
28/*
29 * Make sure our attempts to over run the kernel stack doesn't trigger
30 * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
31 * recurse past the end of THREAD_SIZE by default.
32 */
33#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
34#define REC_STACK_SIZE (_AC(CONFIG_FRAME_WARN, UL) / 2)
35#else
36#define REC_STACK_SIZE (THREAD_SIZE / 8UL)
37#endif
38#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
39
40static int recur_count = REC_NUM_DEFAULT;
41
42static DEFINE_SPINLOCK(lock_me_up);
43
44/*
45 * Make sure compiler does not optimize this function or stack frame away:
46 * - function marked noinline
47 * - stack variables are marked volatile
48 * - stack variables are written (memset()) and read (buf[..] passed as arg)
49 * - function may have external effects (memzero_explicit())
50 * - no tail recursion possible
51 */
52static int noinline recursive_loop(int remaining)
53{
54 volatile char buf[REC_STACK_SIZE];
55 volatile int ret;
56
57 memset((void *)buf, remaining & 0xFF, sizeof(buf));
58 if (!remaining)
59 ret = 0;
60 else
61 ret = recursive_loop((int)buf[remaining % sizeof(buf)] - 1);
62 memzero_explicit((void *)buf, sizeof(buf));
63 return ret;
64}
65
66/* If the depth is negative, use the default, otherwise keep parameter. */
67void __init lkdtm_bugs_init(int *recur_param)
68{
69 if (*recur_param < 0)
70 *recur_param = recur_count;
71 else
72 recur_count = *recur_param;
73}
74
75static void lkdtm_PANIC(void)
76{
77 panic("dumptest");
78}
79
80static int panic_stop_irqoff_fn(void *arg)
81{
82 atomic_t *v = arg;
83
84 /*
85 * As stop_machine() disables interrupts, all CPUs within this function
86 * have interrupts disabled and cannot take a regular IPI.
87 *
88 * The last CPU which enters here will trigger a panic, and as all CPUs
89 * cannot take a regular IPI, we'll only be able to stop secondaries if
90 * smp_send_stop() or crash_smp_send_stop() uses an NMI.
91 */
92 if (atomic_inc_return(v) == num_online_cpus())
93 panic("panic stop irqoff test");
94
95 for (;;)
96 cpu_relax();
97}
98
99static void lkdtm_PANIC_STOP_IRQOFF(void)
100{
101 atomic_t v = ATOMIC_INIT(0);
102 stop_machine(panic_stop_irqoff_fn, &v, cpu_online_mask);
103}
104
105static bool wait_for_panic;
106
107static enum hrtimer_restart panic_in_hardirq(struct hrtimer *timer)
108{
109 panic("from hard IRQ context");
110
111 wait_for_panic = false;
112 return HRTIMER_NORESTART;
113}
114
115static void lkdtm_PANIC_IN_HARDIRQ(void)
116{
117 struct hrtimer timer;
118
119 wait_for_panic = true;
120 hrtimer_setup_on_stack(&timer, panic_in_hardirq,
121 CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
122 hrtimer_start(&timer, us_to_ktime(100), HRTIMER_MODE_REL_HARD);
123
124 while (READ_ONCE(wait_for_panic))
125 cpu_relax();
126
127 hrtimer_cancel(&timer);
128}
129
130static void lkdtm_BUG(void)
131{
132 BUG();
133}
134
135static bool wait_for_bug;
136
137static enum hrtimer_restart bug_in_hardirq(struct hrtimer *timer)
138{
139 BUG();
140
141 wait_for_bug = false;
142 return HRTIMER_NORESTART;
143}
144
145static void lkdtm_BUG_IN_HARDIRQ(void)
146{
147 struct hrtimer timer;
148
149 wait_for_bug = true;
150 hrtimer_setup_on_stack(&timer, bug_in_hardirq,
151 CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
152 hrtimer_start(&timer, us_to_ktime(100), HRTIMER_MODE_REL_HARD);
153
154 while (READ_ONCE(wait_for_bug))
155 cpu_relax();
156
157 hrtimer_cancel(&timer);
158}
159
160static int warn_counter;
161
162static void lkdtm_WARNING(void)
163{
164 WARN_ON(++warn_counter);
165}
166
167static void lkdtm_WARNING_MESSAGE(void)
168{
169 WARN(1, "Warning message trigger count: %d\n", ++warn_counter);
170}
171
172static void lkdtm_EXCEPTION(void)
173{
174 *((volatile int *) 0) = 0;
175}
176
177static void lkdtm_LOOP(void)
178{
179 for (;;)
180 ;
181}
182
183static void lkdtm_EXHAUST_STACK(void)
184{
185 pr_info("Calling function with %lu frame size to depth %d ...\n",
186 REC_STACK_SIZE, recur_count);
187 recursive_loop(recur_count);
188 pr_info("FAIL: survived without exhausting stack?!\n");
189}
190
191static noinline void __lkdtm_CORRUPT_STACK(void *stack)
192{
193 memset(stack, '\xff', 64);
194}
195
196/* This should trip the stack canary, not corrupt the return address. */
197static noinline void lkdtm_CORRUPT_STACK(void)
198{
199 /* Use default char array length that triggers stack protection. */
200 char data[8] __aligned(sizeof(void *));
201
202 pr_info("Corrupting stack containing char array ...\n");
203 __lkdtm_CORRUPT_STACK((void *)&data);
204}
205
206/* Same as above but will only get a canary with -fstack-protector-strong */
207static noinline void lkdtm_CORRUPT_STACK_STRONG(void)
208{
209 union {
210 unsigned short shorts[4];
211 unsigned long *ptr;
212 } data __aligned(sizeof(void *));
213
214 pr_info("Corrupting stack containing union ...\n");
215 __lkdtm_CORRUPT_STACK((void *)&data);
216}
217
218static pid_t stack_pid;
219static unsigned long stack_addr;
220
221static void lkdtm_REPORT_STACK(void)
222{
223 volatile uintptr_t magic;
224 pid_t pid = task_pid_nr(current);
225
226 if (pid != stack_pid) {
227 pr_info("Starting stack offset tracking for pid %d\n", pid);
228 stack_pid = pid;
229 stack_addr = (uintptr_t)&magic;
230 }
231
232 pr_info("Stack offset: %d\n", (int)(stack_addr - (uintptr_t)&magic));
233}
234
235static pid_t stack_canary_pid;
236static unsigned long stack_canary;
237static unsigned long stack_canary_offset;
238
239static noinline void __lkdtm_REPORT_STACK_CANARY(void *stack)
240{
241 int i = 0;
242 pid_t pid = task_pid_nr(current);
243 unsigned long *canary = (unsigned long *)stack;
244 unsigned long current_offset = 0, init_offset = 0;
245
246 /* Do our best to find the canary in a 16 word window ... */
247 for (i = 1; i < 16; i++) {
248 canary = (unsigned long *)stack + i;
249#ifdef CONFIG_STACKPROTECTOR
250 if (*canary == current->stack_canary)
251 current_offset = i;
252 if (*canary == init_task.stack_canary)
253 init_offset = i;
254#endif
255 }
256
257 if (current_offset == 0) {
258 /*
259 * If the canary doesn't match what's in the task_struct,
260 * we're either using a global canary or the stack frame
261 * layout changed.
262 */
263 if (init_offset != 0) {
264 pr_err("FAIL: global stack canary found at offset %ld (canary for pid %d matches init_task's)!\n",
265 init_offset, pid);
266 } else {
267 pr_warn("FAIL: did not correctly locate stack canary :(\n");
268 pr_expected_config(CONFIG_STACKPROTECTOR);
269 }
270
271 return;
272 } else if (init_offset != 0) {
273 pr_warn("WARNING: found both current and init_task canaries nearby?!\n");
274 }
275
276 canary = (unsigned long *)stack + current_offset;
277 if (stack_canary_pid == 0) {
278 stack_canary = *canary;
279 stack_canary_pid = pid;
280 stack_canary_offset = current_offset;
281 pr_info("Recorded stack canary for pid %d at offset %ld\n",
282 stack_canary_pid, stack_canary_offset);
283 } else if (pid == stack_canary_pid) {
284 pr_warn("ERROR: saw pid %d again -- please use a new pid\n", pid);
285 } else {
286 if (current_offset != stack_canary_offset) {
287 pr_warn("ERROR: canary offset changed from %ld to %ld!?\n",
288 stack_canary_offset, current_offset);
289 return;
290 }
291
292 if (*canary == stack_canary) {
293 pr_warn("FAIL: canary identical for pid %d and pid %d at offset %ld!\n",
294 stack_canary_pid, pid, current_offset);
295 } else {
296 pr_info("ok: stack canaries differ between pid %d and pid %d at offset %ld.\n",
297 stack_canary_pid, pid, current_offset);
298 /* Reset the test. */
299 stack_canary_pid = 0;
300 }
301 }
302}
303
304static void lkdtm_REPORT_STACK_CANARY(void)
305{
306 /* Use default char array length that triggers stack protection. */
307 char data[8] __aligned(sizeof(void *)) = { };
308
309 __lkdtm_REPORT_STACK_CANARY((void *)&data);
310}
311
312static void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)
313{
314 static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5};
315 u32 *p;
316 u32 val = 0x12345678;
317
318 p = (u32 *)(data + 1);
319 if (*p == 0)
320 val = 0x87654321;
321 *p = val;
322
323 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
324 pr_err("XFAIL: arch has CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS\n");
325}
326
327static void lkdtm_SOFTLOCKUP(void)
328{
329 preempt_disable();
330 for (;;)
331 cpu_relax();
332}
333
334static void lkdtm_HARDLOCKUP(void)
335{
336 local_irq_disable();
337 for (;;)
338 cpu_relax();
339}
340
341static void __lkdtm_SMP_CALL_LOCKUP(void *unused)
342{
343 for (;;)
344 cpu_relax();
345}
346
347static void lkdtm_SMP_CALL_LOCKUP(void)
348{
349 unsigned int cpu, target;
350
351 cpus_read_lock();
352
353 cpu = get_cpu();
354 target = cpumask_any_but(cpu_online_mask, cpu);
355
356 if (target >= nr_cpu_ids) {
357 pr_err("FAIL: no other online CPUs\n");
358 goto out_put_cpus;
359 }
360
361 smp_call_function_single(target, __lkdtm_SMP_CALL_LOCKUP, NULL, 1);
362
363 pr_err("FAIL: did not hang\n");
364
365out_put_cpus:
366 put_cpu();
367 cpus_read_unlock();
368}
369
370static void lkdtm_SPINLOCKUP(void)
371{
372 /* Must be called twice to trigger. */
373 spin_lock(&lock_me_up);
374 /* Let sparse know we intended to exit holding the lock. */
375 __release(&lock_me_up);
376}
377
378static void __noreturn lkdtm_HUNG_TASK(void)
379{
380 set_current_state(TASK_UNINTERRUPTIBLE);
381 schedule();
382 BUG();
383}
384
385static volatile unsigned int huge = INT_MAX - 2;
386static volatile unsigned int ignored;
387
388static void lkdtm_OVERFLOW_SIGNED(void)
389{
390 int value;
391
392 value = huge;
393 pr_info("Normal signed addition ...\n");
394 value += 1;
395 ignored = value;
396
397 pr_info("Overflowing signed addition ...\n");
398 value += 4;
399 ignored = value;
400}
401
402
403static void lkdtm_OVERFLOW_UNSIGNED(void)
404{
405 unsigned int value;
406
407 value = huge;
408 pr_info("Normal unsigned addition ...\n");
409 value += 1;
410 ignored = value;
411
412 pr_info("Overflowing unsigned addition ...\n");
413 value += 4;
414 ignored = value;
415}
416
417/* Intentionally using unannotated flex array definition. */
418struct array_bounds_flex_array {
419 int one;
420 int two;
421 char data[];
422};
423
424struct array_bounds {
425 int one;
426 int two;
427 char data[8];
428 int three;
429};
430
431static void lkdtm_ARRAY_BOUNDS(void)
432{
433 struct array_bounds_flex_array *not_checked;
434 struct array_bounds *checked;
435 volatile int i;
436
437 not_checked = kmalloc(sizeof(*not_checked) * 2, GFP_KERNEL);
438 checked = kmalloc(sizeof(*checked) * 2, GFP_KERNEL);
439 if (!not_checked || !checked) {
440 kfree(not_checked);
441 kfree(checked);
442 return;
443 }
444
445 pr_info("Array access within bounds ...\n");
446 /* For both, touch all bytes in the actual member size. */
447 for (i = 0; i < sizeof(checked->data); i++)
448 checked->data[i] = 'A';
449 /*
450 * For the uninstrumented flex array member, also touch 1 byte
451 * beyond to verify it is correctly uninstrumented.
452 */
453 for (i = 0; i < 2; i++)
454 not_checked->data[i] = 'A';
455
456 pr_info("Array access beyond bounds ...\n");
457 for (i = 0; i < sizeof(checked->data) + 1; i++)
458 checked->data[i] = 'B';
459
460 kfree(not_checked);
461 kfree(checked);
462 pr_err("FAIL: survived array bounds overflow!\n");
463 if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
464 pr_expected_config(CONFIG_UBSAN_TRAP);
465 else
466 pr_expected_config(CONFIG_UBSAN_BOUNDS);
467}
468
469struct lkdtm_cb_fam {
470 unsigned long flags;
471 int count;
472 int array[] __counted_by(count);
473};
474
475static volatile int element_count = 4;
476
477static void lkdtm_FAM_BOUNDS(void)
478{
479 struct lkdtm_cb_fam *inst;
480
481 inst = kzalloc_flex(*inst, array, element_count + 1);
482 if (!inst) {
483 pr_err("FAIL: could not allocate test struct!\n");
484 return;
485 }
486
487 inst->count = element_count;
488 pr_info("Array access within bounds ...\n");
489 inst->array[1] = element_count;
490 ignored = inst->array[1];
491
492 pr_info("Array access beyond bounds ...\n");
493 inst->array[element_count] = element_count;
494 ignored = inst->array[element_count];
495
496 kfree(inst);
497
498 pr_err("FAIL: survived access of invalid flexible array member index!\n");
499
500 if (!IS_ENABLED(CONFIG_CC_HAS_COUNTED_BY))
501 pr_warn("This is expected since this %s was built with a compiler that does not support __counted_by\n",
502 lkdtm_kernel_info);
503 else if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
504 pr_expected_config(CONFIG_UBSAN_TRAP);
505 else
506 pr_expected_config(CONFIG_UBSAN_BOUNDS);
507}
508
509struct lkdtm_extra {
510 short a, b;
511 u16 sixteen;
512 u32 bigger;
513 u64 biggest;
514};
515
516struct lkdtm_cb_ptr {
517 int a, b, c;
518 int nr_extra;
519 char *buf __counted_by_ptr(len);
520 size_t len;
521 struct lkdtm_extra *extra __counted_by_ptr(nr_extra);
522};
523
524static noinline void check_ptr_len(struct lkdtm_cb_ptr *p, size_t len)
525{
526 if (__member_size(p->buf) != len)
527 pr_err("FAIL: could not determine size of inst->buf: %zu\n",
528 __member_size(p->buf));
529 else
530 pr_info("good: inst->buf length is %zu\n", len);
531}
532
533static void lkdtm_PTR_BOUNDS(void)
534{
535 struct lkdtm_cb_ptr *inst;
536
537 inst = kzalloc_obj(*inst);
538 if (!inst) {
539 pr_err("FAIL: could not allocate struct lkdtm_cb_ptr!\n");
540 return;
541 }
542
543 inst->buf = kzalloc(element_count, GFP_KERNEL);
544 if (!inst->buf) {
545 pr_err("FAIL: could not allocate inst->buf!\n");
546 return;
547 }
548 inst->len = element_count;
549
550 /* Double element_count */
551 inst->extra = kzalloc_objs(*inst->extra, element_count * 2);
552 inst->nr_extra = element_count * 2;
553
554 pr_info("Pointer access within bounds ...\n");
555 check_ptr_len(inst, 4);
556 /* All 4 bytes */
557 inst->buf[0] = 'A';
558 inst->buf[1] = 'B';
559 inst->buf[2] = 'C';
560 inst->buf[3] = 'D';
561 /* Halfway into the array */
562 inst->extra[element_count].biggest = 0x1000;
563
564 pr_info("Pointer access beyond bounds ...\n");
565 ignored = inst->extra[inst->nr_extra].b;
566
567 kfree(inst->extra);
568 kfree(inst->buf);
569 kfree(inst);
570
571 pr_err("FAIL: survived access of invalid pointer member offset!\n");
572
573 if (!IS_ENABLED(CONFIG_CC_HAS_COUNTED_BY_PTR))
574 pr_warn("This is expected since this %s was built with a compiler that does not support __counted_by_ptr\n",
575 lkdtm_kernel_info);
576 else if (IS_ENABLED(CONFIG_UBSAN_BOUNDS))
577 pr_expected_config(CONFIG_UBSAN_TRAP);
578 else
579 pr_expected_config(CONFIG_UBSAN_BOUNDS);
580}
581
582static void lkdtm_CORRUPT_LIST_ADD(void)
583{
584 /*
585 * Initially, an empty list via LIST_HEAD:
586 * test_head.next = &test_head
587 * test_head.prev = &test_head
588 */
589 LIST_HEAD(test_head);
590 struct lkdtm_list good, bad;
591 void *target[2] = { };
592 void *redirection = &target;
593
594 pr_info("attempting good list addition\n");
595
596 /*
597 * Adding to the list performs these actions:
598 * test_head.next->prev = &good.node
599 * good.node.next = test_head.next
600 * good.node.prev = test_head
601 * test_head.next = good.node
602 */
603 list_add(&good.node, &test_head);
604
605 pr_info("attempting corrupted list addition\n");
606 /*
607 * In simulating this "write what where" primitive, the "what" is
608 * the address of &bad.node, and the "where" is the address held
609 * by "redirection".
610 */
611 test_head.next = redirection;
612 list_add(&bad.node, &test_head);
613
614 if (target[0] == NULL && target[1] == NULL)
615 pr_err("Overwrite did not happen, but no BUG?!\n");
616 else {
617 pr_err("list_add() corruption not detected!\n");
618 pr_expected_config(CONFIG_LIST_HARDENED);
619 }
620}
621
622static void lkdtm_CORRUPT_LIST_DEL(void)
623{
624 LIST_HEAD(test_head);
625 struct lkdtm_list item;
626 void *target[2] = { };
627 void *redirection = &target;
628
629 list_add(&item.node, &test_head);
630
631 pr_info("attempting good list removal\n");
632 list_del(&item.node);
633
634 pr_info("attempting corrupted list removal\n");
635 list_add(&item.node, &test_head);
636
637 /* As with the list_add() test above, this corrupts "next". */
638 item.node.next = redirection;
639 list_del(&item.node);
640
641 if (target[0] == NULL && target[1] == NULL)
642 pr_err("Overwrite did not happen, but no BUG?!\n");
643 else {
644 pr_err("list_del() corruption not detected!\n");
645 pr_expected_config(CONFIG_LIST_HARDENED);
646 }
647}
648
649/* Test that VMAP_STACK is actually allocating with a leading guard page */
650static void lkdtm_STACK_GUARD_PAGE_LEADING(void)
651{
652 const unsigned char *stack = task_stack_page(current);
653 const unsigned char *ptr = stack - 1;
654 volatile unsigned char byte;
655
656 pr_info("attempting bad read from page below current stack\n");
657
658 byte = *ptr;
659
660 pr_err("FAIL: accessed page before stack! (byte: %x)\n", byte);
661}
662
663/* Test that VMAP_STACK is actually allocating with a trailing guard page */
664static void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
665{
666 const unsigned char *stack = task_stack_page(current);
667 const unsigned char *ptr = stack + THREAD_SIZE;
668 volatile unsigned char byte;
669
670 pr_info("attempting bad read from page above current stack\n");
671
672 byte = *ptr;
673
674 pr_err("FAIL: accessed page after stack! (byte: %x)\n", byte);
675}
676
677static void lkdtm_UNSET_SMEP(void)
678{
679#if IS_ENABLED(CONFIG_X86_64) && !IS_ENABLED(CONFIG_UML)
680#define MOV_CR4_DEPTH 64
681 void (*direct_write_cr4)(unsigned long val);
682 unsigned char *insn;
683 unsigned long cr4;
684 int i;
685
686 cr4 = native_read_cr4();
687
688 if ((cr4 & X86_CR4_SMEP) != X86_CR4_SMEP) {
689 pr_err("FAIL: SMEP not in use\n");
690 return;
691 }
692 cr4 &= ~(X86_CR4_SMEP);
693
694 pr_info("trying to clear SMEP normally\n");
695 native_write_cr4(cr4);
696 if (cr4 == native_read_cr4()) {
697 pr_err("FAIL: pinning SMEP failed!\n");
698 cr4 |= X86_CR4_SMEP;
699 pr_info("restoring SMEP\n");
700 native_write_cr4(cr4);
701 return;
702 }
703 pr_info("ok: SMEP did not get cleared\n");
704
705 /*
706 * To test the post-write pinning verification we need to call
707 * directly into the middle of native_write_cr4() where the
708 * cr4 write happens, skipping any pinning. This searches for
709 * the cr4 writing instruction.
710 */
711 insn = (unsigned char *)native_write_cr4;
712 OPTIMIZER_HIDE_VAR(insn);
713 for (i = 0; i < MOV_CR4_DEPTH; i++) {
714 /* mov %rdi, %cr4 */
715 if (insn[i] == 0x0f && insn[i+1] == 0x22 && insn[i+2] == 0xe7)
716 break;
717 /* mov %rdi,%rax; mov %rax, %cr4 */
718 if (insn[i] == 0x48 && insn[i+1] == 0x89 &&
719 insn[i+2] == 0xf8 && insn[i+3] == 0x0f &&
720 insn[i+4] == 0x22 && insn[i+5] == 0xe0)
721 break;
722 }
723 if (i >= MOV_CR4_DEPTH) {
724 pr_info("ok: cannot locate cr4 writing call gadget\n");
725 return;
726 }
727 direct_write_cr4 = (void *)(insn + i);
728
729 pr_info("trying to clear SMEP with call gadget\n");
730 direct_write_cr4(cr4);
731 if (native_read_cr4() & X86_CR4_SMEP) {
732 pr_info("ok: SMEP removal was reverted\n");
733 } else {
734 pr_err("FAIL: cleared SMEP not detected!\n");
735 cr4 |= X86_CR4_SMEP;
736 pr_info("restoring SMEP\n");
737 native_write_cr4(cr4);
738 }
739#else
740 pr_err("XFAIL: this test is x86_64-only\n");
741#endif
742}
743
744static void lkdtm_DOUBLE_FAULT(void)
745{
746#if IS_ENABLED(CONFIG_X86_32) && !IS_ENABLED(CONFIG_UML)
747 /*
748 * Trigger #DF by setting the stack limit to zero. This clobbers
749 * a GDT TLS slot, which is okay because the current task will die
750 * anyway due to the double fault.
751 */
752 struct desc_struct d = {
753 .type = 3, /* expand-up, writable, accessed data */
754 .p = 1, /* present */
755 .d = 1, /* 32-bit */
756 .g = 0, /* limit in bytes */
757 .s = 1, /* not system */
758 };
759
760 local_irq_disable();
761 write_gdt_entry(get_cpu_gdt_rw(smp_processor_id()),
762 GDT_ENTRY_TLS_MIN, &d, DESCTYPE_S);
763
764 /*
765 * Put our zero-limit segment in SS and then trigger a fault. The
766 * 4-byte access to (%esp) will fault with #SS, and the attempt to
767 * deliver the fault will recursively cause #SS and result in #DF.
768 * This whole process happens while NMIs and MCEs are blocked by the
769 * MOV SS window. This is nice because an NMI with an invalid SS
770 * would also double-fault, resulting in the NMI or MCE being lost.
771 */
772 asm volatile ("movw %0, %%ss; addl $0, (%%esp)" ::
773 "r" ((unsigned short)(GDT_ENTRY_TLS_MIN << 3)));
774
775 pr_err("FAIL: tried to double fault but didn't die\n");
776#else
777 pr_err("XFAIL: this test is ia32-only\n");
778#endif
779}
780
781#ifdef CONFIG_ARM64
782static noinline void change_pac_parameters(void)
783{
784 if (IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL)) {
785 /* Reset the keys of current task */
786 ptrauth_thread_init_kernel(current);
787 ptrauth_thread_switch_kernel(current);
788 }
789}
790#endif
791
792static noinline void lkdtm_CORRUPT_PAC(void)
793{
794#ifdef CONFIG_ARM64
795#define CORRUPT_PAC_ITERATE 10
796 int i;
797
798 if (!IS_ENABLED(CONFIG_ARM64_PTR_AUTH_KERNEL))
799 pr_err("FAIL: kernel not built with CONFIG_ARM64_PTR_AUTH_KERNEL\n");
800
801 if (!system_supports_address_auth()) {
802 pr_err("FAIL: CPU lacks pointer authentication feature\n");
803 return;
804 }
805
806 pr_info("changing PAC parameters to force function return failure...\n");
807 /*
808 * PAC is a hash value computed from input keys, return address and
809 * stack pointer. As pac has fewer bits so there is a chance of
810 * collision, so iterate few times to reduce the collision probability.
811 */
812 for (i = 0; i < CORRUPT_PAC_ITERATE; i++)
813 change_pac_parameters();
814
815 pr_err("FAIL: survived PAC changes! Kernel may be unstable from here\n");
816#else
817 pr_err("XFAIL: this test is arm64-only\n");
818#endif
819}
820
821static void __maybe_unused lkdtm_EFI_RUNTIME_CRASH(void)
822{
823 static unsigned long size __ro_after_init = sizeof(efi_char16_t);
824 efi_status_t status;
825
826 if (!efi.get_next_variable ||
827 !efi_enabled(EFI_RUNTIME_SERVICES) ||
828 !efi_rt_services_supported(EFI_RT_SUPPORTED_GET_NEXT_VARIABLE_NAME)) {
829 pr_err("FAIL: EFI GetNextVariableName() is not available\n");
830 return;
831 }
832
833 /*
834 * Provoke a fault by asking the firmware to write to a read-only
835 * variable.
836 */
837 status = efi.get_next_variable(&size, L"", &(efi_guid_t){});
838
839 if (status != EFI_ABORTED || efi_enabled(EFI_RUNTIME_SERVICES))
840 pr_err("FAIL: EFI GetNextVariable() did not abort (%#lx)\n",
841 status);
842}
843
844static struct crashtype crashtypes[] = {
845 CRASHTYPE(PANIC),
846 CRASHTYPE(PANIC_STOP_IRQOFF),
847 CRASHTYPE(PANIC_IN_HARDIRQ),
848 CRASHTYPE(BUG),
849 CRASHTYPE(BUG_IN_HARDIRQ),
850 CRASHTYPE(WARNING),
851 CRASHTYPE(WARNING_MESSAGE),
852 CRASHTYPE(EXCEPTION),
853 CRASHTYPE(LOOP),
854 CRASHTYPE(EXHAUST_STACK),
855 CRASHTYPE(CORRUPT_STACK),
856 CRASHTYPE(CORRUPT_STACK_STRONG),
857 CRASHTYPE(REPORT_STACK),
858 CRASHTYPE(REPORT_STACK_CANARY),
859 CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
860 CRASHTYPE(SOFTLOCKUP),
861 CRASHTYPE(HARDLOCKUP),
862 CRASHTYPE(SMP_CALL_LOCKUP),
863 CRASHTYPE(SPINLOCKUP),
864 CRASHTYPE(HUNG_TASK),
865 CRASHTYPE(OVERFLOW_SIGNED),
866 CRASHTYPE(OVERFLOW_UNSIGNED),
867 CRASHTYPE(ARRAY_BOUNDS),
868 CRASHTYPE(FAM_BOUNDS),
869 CRASHTYPE(PTR_BOUNDS),
870 CRASHTYPE(CORRUPT_LIST_ADD),
871 CRASHTYPE(CORRUPT_LIST_DEL),
872 CRASHTYPE(STACK_GUARD_PAGE_LEADING),
873 CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
874 CRASHTYPE(UNSET_SMEP),
875 CRASHTYPE(DOUBLE_FAULT),
876 CRASHTYPE(CORRUPT_PAC),
877#ifdef CONFIG_EFI
878 CRASHTYPE(EFI_RUNTIME_CRASH),
879#endif
880};
881
882struct crashtype_category bugs_crashtypes = {
883 .crashtypes = crashtypes,
884 .len = ARRAY_SIZE(crashtypes),
885};