1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/exit.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8#include <linux/mm.h>
9#include <linux/slab.h>
10#include <linux/sched/autogroup.h>
11#include <linux/sched/mm.h>
12#include <linux/sched/stat.h>
13#include <linux/sched/task.h>
14#include <linux/sched/task_stack.h>
15#include <linux/sched/cputime.h>
16#include <linux/interrupt.h>
17#include <linux/module.h>
18#include <linux/capability.h>
19#include <linux/completion.h>
20#include <linux/personality.h>
21#include <linux/tty.h>
22#include <linux/iocontext.h>
23#include <linux/key.h>
24#include <linux/cpu.h>
25#include <linux/acct.h>
26#include <linux/tsacct_kern.h>
27#include <linux/file.h>
28#include <linux/freezer.h>
29#include <linux/binfmts.h>
30#include <linux/nsproxy.h>
31#include <linux/pid_namespace.h>
32#include <linux/ptrace.h>
33#include <linux/profile.h>
34#include <linux/mount.h>
35#include <linux/proc_fs.h>
36#include <linux/kthread.h>
37#include <linux/mempolicy.h>
38#include <linux/taskstats_kern.h>
39#include <linux/delayacct.h>
40#include <linux/cgroup.h>
41#include <linux/syscalls.h>
42#include <linux/signal.h>
43#include <linux/posix-timers.h>
44#include <linux/cn_proc.h>
45#include <linux/mutex.h>
46#include <linux/futex.h>
47#include <linux/pipe_fs_i.h>
48#include <linux/audit.h> /* for audit_free() */
49#include <linux/resource.h>
50#include <linux/task_io_accounting_ops.h>
51#include <linux/blkdev.h>
52#include <linux/task_work.h>
53#include <linux/fs_struct.h>
54#include <linux/init_task.h>
55#include <linux/perf_event.h>
56#include <trace/events/sched.h>
57#include <linux/hw_breakpoint.h>
58#include <linux/oom.h>
59#include <linux/writeback.h>
60#include <linux/shm.h>
61#include <linux/kcov.h>
62#include <linux/kmsan.h>
63#include <linux/random.h>
64#include <linux/rcuwait.h>
65#include <linux/compat.h>
66#include <linux/io_uring.h>
67#include <linux/kprobes.h>
68#include <linux/rethook.h>
69#include <linux/sysfs.h>
70#include <linux/user_events.h>
71#include <linux/unwind_deferred.h>
72#include <linux/uaccess.h>
73#include <linux/pidfs.h>
74
75#include <uapi/linux/wait.h>
76
77#include <asm/unistd.h>
78#include <asm/mmu_context.h>
79
80#include "exit.h"
81
82/*
83 * The default value should be high enough to not crash a system that randomly
84 * crashes its kernel from time to time, but low enough to at least not permit
85 * overflowing 32-bit refcounts or the ldsem writer count.
86 */
87static unsigned int oops_limit = 10000;
88
89#ifdef CONFIG_SYSCTL
90static const struct ctl_table kern_exit_table[] = {
91 {
92 .procname = "oops_limit",
93 .data = &oops_limit,
94 .maxlen = sizeof(oops_limit),
95 .mode = 0644,
96 .proc_handler = proc_douintvec,
97 },
98};
99
100static __init int kernel_exit_sysctls_init(void)
101{
102 register_sysctl_init("kernel", kern_exit_table);
103 return 0;
104}
105late_initcall(kernel_exit_sysctls_init);
106#endif
107
108static atomic_t oops_count = ATOMIC_INIT(0);
109
110#ifdef CONFIG_SYSFS
111static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr,
112 char *page)
113{
114 return sysfs_emit(buf: page, fmt: "%d\n", atomic_read(v: &oops_count));
115}
116
117static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count);
118
119static __init int kernel_exit_sysfs_init(void)
120{
121 sysfs_add_file_to_group(kobj: kernel_kobj, attr: &oops_count_attr.attr, NULL);
122 return 0;
123}
124late_initcall(kernel_exit_sysfs_init);
125#endif
126
127/*
128 * For things release_task() would like to do *after* tasklist_lock is released.
129 */
130struct release_task_post {
131 struct pid *pids[PIDTYPE_MAX];
132};
133
134static void __unhash_process(struct release_task_post *post, struct task_struct *p,
135 bool group_dead)
136{
137 struct pid *pid = task_pid(task: p);
138
139 nr_threads--;
140
141 detach_pid(pids: post->pids, task: p, PIDTYPE_PID);
142 wake_up_all(&pid->wait_pidfd);
143
144 if (group_dead) {
145 detach_pid(pids: post->pids, task: p, PIDTYPE_TGID);
146 detach_pid(pids: post->pids, task: p, PIDTYPE_PGID);
147 detach_pid(pids: post->pids, task: p, PIDTYPE_SID);
148
149 list_del_rcu(entry: &p->tasks);
150 list_del_init(entry: &p->sibling);
151 __this_cpu_dec(process_counts);
152 }
153 list_del_rcu(entry: &p->thread_node);
154}
155
156/*
157 * This function expects the tasklist_lock write-locked.
158 */
159static void __exit_signal(struct release_task_post *post, struct task_struct *tsk)
160{
161 struct signal_struct *sig = tsk->signal;
162 bool group_dead = thread_group_leader(p: tsk);
163 struct sighand_struct *sighand;
164 struct tty_struct *tty;
165 u64 utime, stime;
166
167 sighand = rcu_dereference_check(tsk->sighand,
168 lockdep_tasklist_lock_is_held());
169 spin_lock(lock: &sighand->siglock);
170
171#ifdef CONFIG_POSIX_TIMERS
172 posix_cpu_timers_exit(task: tsk);
173 if (group_dead)
174 posix_cpu_timers_exit_group(task: tsk);
175#endif
176
177 if (group_dead) {
178 tty = sig->tty;
179 sig->tty = NULL;
180 } else {
181 /*
182 * If there is any task waiting for the group exit
183 * then notify it:
184 */
185 if (sig->notify_count > 0 && !--sig->notify_count)
186 wake_up_process(tsk: sig->group_exec_task);
187
188 if (tsk == sig->curr_target)
189 sig->curr_target = next_thread(p: tsk);
190 }
191
192 /*
193 * Accumulate here the counters for all threads as they die. We could
194 * skip the group leader because it is the last user of signal_struct,
195 * but we want to avoid the race with thread_group_cputime() which can
196 * see the empty ->thread_head list.
197 */
198 task_cputime(t: tsk, utime: &utime, stime: &stime);
199 write_seqlock(sl: &sig->stats_lock);
200 sig->utime += utime;
201 sig->stime += stime;
202 sig->gtime += task_gtime(t: tsk);
203 sig->min_flt += tsk->min_flt;
204 sig->maj_flt += tsk->maj_flt;
205 sig->nvcsw += tsk->nvcsw;
206 sig->nivcsw += tsk->nivcsw;
207 sig->inblock += task_io_get_inblock(p: tsk);
208 sig->oublock += task_io_get_oublock(p: tsk);
209 task_io_accounting_add(dst: &sig->ioac, src: &tsk->ioac);
210 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
211 sig->nr_threads--;
212 __unhash_process(post, p: tsk, group_dead);
213 write_sequnlock(sl: &sig->stats_lock);
214
215 tsk->sighand = NULL;
216 spin_unlock(lock: &sighand->siglock);
217
218 __cleanup_sighand(sighand);
219 if (group_dead)
220 tty_kref_put(tty);
221}
222
223static void delayed_put_task_struct(struct rcu_head *rhp)
224{
225 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
226
227 kprobe_flush_task(tsk);
228 rethook_flush_task(tk: tsk);
229 perf_event_delayed_put(task: tsk);
230 trace_sched_process_free(p: tsk);
231 put_task_struct(t: tsk);
232}
233
234void put_task_struct_rcu_user(struct task_struct *task)
235{
236 if (refcount_dec_and_test(r: &task->rcu_users))
237 call_rcu(head: &task->rcu, func: delayed_put_task_struct);
238}
239
240void __weak release_thread(struct task_struct *dead_task)
241{
242}
243
244void release_task(struct task_struct *p)
245{
246 struct release_task_post post;
247 struct task_struct *leader;
248 struct pid *thread_pid;
249 int zap_leader;
250repeat:
251 memset(s: &post, c: 0, n: sizeof(post));
252
253 /* don't need to get the RCU readlock here - the process is dead and
254 * can't be modifying its own credentials. But shut RCU-lockdep up */
255 rcu_read_lock();
256 dec_rlimit_ucounts(task_ucounts(p), type: UCOUNT_RLIMIT_NPROC, v: 1);
257 rcu_read_unlock();
258
259 pidfs_exit(tsk: p);
260 cgroup_release(p);
261
262 /* Retrieve @thread_pid before __unhash_process() may set it to NULL. */
263 thread_pid = task_pid(task: p);
264
265 write_lock_irq(&tasklist_lock);
266 ptrace_release_task(task: p);
267 __exit_signal(post: &post, tsk: p);
268
269 /*
270 * If we are the last non-leader member of the thread
271 * group, and the leader is zombie, then notify the
272 * group leader's parent process. (if it wants notification.)
273 */
274 zap_leader = 0;
275 leader = p->group_leader;
276 if (leader != p && thread_group_empty(p: leader)
277 && leader->exit_state == EXIT_ZOMBIE) {
278 /* for pidfs_exit() and do_notify_parent() */
279 if (leader->signal->flags & SIGNAL_GROUP_EXIT)
280 leader->exit_code = leader->signal->group_exit_code;
281 /*
282 * If we were the last child thread and the leader has
283 * exited already, and the leader's parent ignores SIGCHLD,
284 * then we are the one who should release the leader.
285 */
286 zap_leader = do_notify_parent(leader, leader->exit_signal);
287 if (zap_leader)
288 leader->exit_state = EXIT_DEAD;
289 }
290
291 write_unlock_irq(&tasklist_lock);
292 /* @thread_pid can't go away until free_pids() below */
293 proc_flush_pid(thread_pid);
294 add_device_randomness(buf: &p->se.sum_exec_runtime,
295 len: sizeof(p->se.sum_exec_runtime));
296 free_pids(pids: post.pids);
297 release_thread(dead_task: p);
298 /*
299 * This task was already removed from the process/thread/pid lists
300 * and lock_task_sighand(p) can't succeed. Nobody else can touch
301 * ->pending or, if group dead, signal->shared_pending. We can call
302 * flush_sigqueue() lockless.
303 */
304 flush_sigqueue(queue: &p->pending);
305 if (thread_group_leader(p))
306 flush_sigqueue(queue: &p->signal->shared_pending);
307
308 put_task_struct_rcu_user(task: p);
309
310 p = leader;
311 if (unlikely(zap_leader))
312 goto repeat;
313}
314
315int rcuwait_wake_up(struct rcuwait *w)
316{
317 int ret = 0;
318 struct task_struct *task;
319
320 rcu_read_lock();
321
322 /*
323 * Order condition vs @task, such that everything prior to the load
324 * of @task is visible. This is the condition as to why the user called
325 * rcuwait_wake() in the first place. Pairs with set_current_state()
326 * barrier (A) in rcuwait_wait_event().
327 *
328 * WAIT WAKE
329 * [S] tsk = current [S] cond = true
330 * MB (A) MB (B)
331 * [L] cond [L] tsk
332 */
333 smp_mb(); /* (B) */
334
335 task = rcu_dereference(w->task);
336 if (task)
337 ret = wake_up_process(tsk: task);
338 rcu_read_unlock();
339
340 return ret;
341}
342EXPORT_SYMBOL_GPL(rcuwait_wake_up);
343
344/*
345 * Determine if a process group is "orphaned", according to the POSIX
346 * definition in 2.2.2.52. Orphaned process groups are not to be affected
347 * by terminal-generated stop signals. Newly orphaned process groups are
348 * to receive a SIGHUP and a SIGCONT.
349 *
350 * "I ask you, have you ever known what it is to be an orphan?"
351 */
352static int will_become_orphaned_pgrp(struct pid *pgrp,
353 struct task_struct *ignored_task)
354{
355 struct task_struct *p;
356
357 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
358 if ((p == ignored_task) ||
359 (p->exit_state && thread_group_empty(p)) ||
360 is_global_init(tsk: p->real_parent))
361 continue;
362
363 if (task_pgrp(task: p->real_parent) != pgrp &&
364 task_session(task: p->real_parent) == task_session(task: p))
365 return 0;
366 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
367
368 return 1;
369}
370
371int is_current_pgrp_orphaned(void)
372{
373 int retval;
374
375 read_lock(&tasklist_lock);
376 retval = will_become_orphaned_pgrp(pgrp: task_pgrp(current), NULL);
377 read_unlock(&tasklist_lock);
378
379 return retval;
380}
381
382static bool has_stopped_jobs(struct pid *pgrp)
383{
384 struct task_struct *p;
385
386 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
387 if (p->signal->flags & SIGNAL_STOP_STOPPED)
388 return true;
389 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
390
391 return false;
392}
393
394/*
395 * Check to see if any process groups have become orphaned as
396 * a result of our exiting, and if they have any stopped jobs,
397 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
398 */
399static void
400kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
401{
402 struct pid *pgrp = task_pgrp(task: tsk);
403 struct task_struct *ignored_task = tsk;
404
405 if (!parent)
406 /* exit: our father is in a different pgrp than
407 * we are and we were the only connection outside.
408 */
409 parent = tsk->real_parent;
410 else
411 /* reparent: our child is in a different pgrp than
412 * we are, and it was the only connection outside.
413 */
414 ignored_task = NULL;
415
416 if (task_pgrp(task: parent) != pgrp &&
417 task_session(task: parent) == task_session(task: tsk) &&
418 will_become_orphaned_pgrp(pgrp, ignored_task) &&
419 has_stopped_jobs(pgrp)) {
420 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
421 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
422 }
423}
424
425static void coredump_task_exit(struct task_struct *tsk,
426 struct core_state *core_state)
427{
428 struct core_thread self;
429
430 self.task = tsk;
431 if (self.task->flags & PF_SIGNALED)
432 self.next = xchg(&core_state->dumper.next, &self);
433 else
434 self.task = NULL;
435 /*
436 * Implies mb(), the result of xchg() must be visible
437 * to core_state->dumper.
438 */
439 if (atomic_dec_and_test(v: &core_state->nr_threads))
440 complete(&core_state->startup);
441
442 for (;;) {
443 set_current_state(TASK_IDLE|TASK_FREEZABLE);
444 if (!self.task) /* see coredump_finish() */
445 break;
446 schedule();
447 }
448 __set_current_state(TASK_RUNNING);
449}
450
451#ifdef CONFIG_MEMCG
452/* drops tasklist_lock if succeeds */
453static bool __try_to_set_owner(struct task_struct *tsk, struct mm_struct *mm)
454{
455 bool ret = false;
456
457 task_lock(tsk);
458 if (likely(tsk->mm == mm)) {
459 /* tsk can't pass exit_mm/exec_mmap and exit */
460 read_unlock(&tasklist_lock);
461 WRITE_ONCE(mm->owner, tsk);
462 lru_gen_migrate_mm(mm);
463 ret = true;
464 }
465 task_unlock(tsk);
466 return ret;
467}
468
469static bool try_to_set_owner(struct task_struct *g, struct mm_struct *mm)
470{
471 struct task_struct *t;
472
473 for_each_thread(g, t) {
474 struct mm_struct *t_mm = READ_ONCE(t->mm);
475 if (t_mm == mm) {
476 if (__try_to_set_owner(t, mm))
477 return true;
478 } else if (t_mm)
479 break;
480 }
481
482 return false;
483}
484
485/*
486 * A task is exiting. If it owned this mm, find a new owner for the mm.
487 */
488void mm_update_next_owner(struct mm_struct *mm)
489{
490 struct task_struct *g, *p = current;
491
492 /*
493 * If the exiting or execing task is not the owner, it's
494 * someone else's problem.
495 */
496 if (mm->owner != p)
497 return;
498 /*
499 * The current owner is exiting/execing and there are no other
500 * candidates. Do not leave the mm pointing to a possibly
501 * freed task structure.
502 */
503 if (atomic_read(&mm->mm_users) <= 1) {
504 WRITE_ONCE(mm->owner, NULL);
505 return;
506 }
507
508 read_lock(&tasklist_lock);
509 /*
510 * Search in the children
511 */
512 list_for_each_entry(g, &p->children, sibling) {
513 if (try_to_set_owner(g, mm))
514 goto ret;
515 }
516 /*
517 * Search in the siblings
518 */
519 list_for_each_entry(g, &p->real_parent->children, sibling) {
520 if (try_to_set_owner(g, mm))
521 goto ret;
522 }
523 /*
524 * Search through everything else, we should not get here often.
525 */
526 for_each_process(g) {
527 if (atomic_read(&mm->mm_users) <= 1)
528 break;
529 if (g->flags & PF_KTHREAD)
530 continue;
531 if (try_to_set_owner(g, mm))
532 goto ret;
533 }
534 read_unlock(&tasklist_lock);
535 /*
536 * We found no owner yet mm_users > 1: this implies that we are
537 * most likely racing with swapoff (try_to_unuse()) or /proc or
538 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
539 */
540 WRITE_ONCE(mm->owner, NULL);
541 ret:
542 return;
543
544}
545#endif /* CONFIG_MEMCG */
546
547/*
548 * Turn us into a lazy TLB process if we
549 * aren't already..
550 */
551static void exit_mm(void)
552{
553 struct mm_struct *mm = current->mm;
554
555 exit_mm_release(current, mm);
556 if (!mm)
557 return;
558 mmap_read_lock(mm);
559 mmgrab_lazy_tlb(mm);
560 BUG_ON(mm != current->active_mm);
561 /* more a memory barrier than a real lock */
562 task_lock(current);
563 /*
564 * When a thread stops operating on an address space, the loop
565 * in membarrier_private_expedited() may not observe that
566 * tsk->mm, and the loop in membarrier_global_expedited() may
567 * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED
568 * rq->membarrier_state, so those would not issue an IPI.
569 * Membarrier requires a memory barrier after accessing
570 * user-space memory, before clearing tsk->mm or the
571 * rq->membarrier_state.
572 */
573 smp_mb__after_spinlock();
574 local_irq_disable();
575 current->mm = NULL;
576 membarrier_update_current_mm(NULL);
577 enter_lazy_tlb(mm, current);
578 local_irq_enable();
579 task_unlock(current);
580 mmap_read_unlock(mm);
581 mm_update_next_owner(mm);
582 mmput(mm);
583 if (test_thread_flag(TIF_MEMDIE))
584 exit_oom_victim();
585}
586
587static struct task_struct *find_alive_thread(struct task_struct *p)
588{
589 struct task_struct *t;
590
591 for_each_thread(p, t) {
592 if (!(t->flags & PF_EXITING))
593 return t;
594 }
595 return NULL;
596}
597
598static struct task_struct *find_child_reaper(struct task_struct *father,
599 struct list_head *dead)
600 __releases(&tasklist_lock)
601 __acquires(&tasklist_lock)
602{
603 struct pid_namespace *pid_ns = task_active_pid_ns(tsk: father);
604 struct task_struct *reaper = pid_ns->child_reaper;
605 struct task_struct *p, *n;
606
607 if (likely(reaper != father))
608 return reaper;
609
610 reaper = find_alive_thread(p: father);
611 if (reaper) {
612 pid_ns->child_reaper = reaper;
613 return reaper;
614 }
615
616 write_unlock_irq(&tasklist_lock);
617
618 list_for_each_entry_safe(p, n, dead, ptrace_entry) {
619 list_del_init(entry: &p->ptrace_entry);
620 release_task(p);
621 }
622
623 zap_pid_ns_processes(pid_ns);
624 write_lock_irq(&tasklist_lock);
625
626 return father;
627}
628
629/*
630 * When we die, we re-parent all our children, and try to:
631 * 1. give them to another thread in our thread group, if such a member exists
632 * 2. give it to the first ancestor process which prctl'd itself as a
633 * child_subreaper for its children (like a service manager)
634 * 3. give it to the init process (PID 1) in our pid namespace
635 */
636static struct task_struct *find_new_reaper(struct task_struct *father,
637 struct task_struct *child_reaper)
638{
639 struct task_struct *thread, *reaper;
640
641 thread = find_alive_thread(p: father);
642 if (thread)
643 return thread;
644
645 if (father->signal->has_child_subreaper) {
646 unsigned int ns_level = task_pid(task: father)->level;
647 /*
648 * Find the first ->is_child_subreaper ancestor in our pid_ns.
649 * We can't check reaper != child_reaper to ensure we do not
650 * cross the namespaces, the exiting parent could be injected
651 * by setns() + fork().
652 * We check pid->level, this is slightly more efficient than
653 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
654 */
655 for (reaper = father->real_parent;
656 task_pid(task: reaper)->level == ns_level;
657 reaper = reaper->real_parent) {
658 if (reaper == &init_task)
659 break;
660 if (!reaper->signal->is_child_subreaper)
661 continue;
662 thread = find_alive_thread(p: reaper);
663 if (thread)
664 return thread;
665 }
666 }
667
668 return child_reaper;
669}
670
671/*
672* Any that need to be release_task'd are put on the @dead list.
673 */
674static void reparent_leader(struct task_struct *father, struct task_struct *p,
675 struct list_head *dead)
676{
677 if (unlikely(p->exit_state == EXIT_DEAD))
678 return;
679
680 /* We don't want people slaying init. */
681 p->exit_signal = SIGCHLD;
682
683 /* If it has exited notify the new parent about this child's death. */
684 if (!p->ptrace &&
685 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
686 if (do_notify_parent(p, p->exit_signal)) {
687 p->exit_state = EXIT_DEAD;
688 list_add(new: &p->ptrace_entry, head: dead);
689 }
690 }
691
692 kill_orphaned_pgrp(tsk: p, parent: father);
693}
694
695/*
696 * Make init inherit all the child processes
697 */
698static void forget_original_parent(struct task_struct *father,
699 struct list_head *dead)
700{
701 struct task_struct *p, *t, *reaper;
702
703 if (unlikely(!list_empty(&father->ptraced)))
704 exit_ptrace(tracer: father, dead);
705
706 /* Can drop and reacquire tasklist_lock */
707 reaper = find_child_reaper(father, dead);
708 if (list_empty(head: &father->children))
709 return;
710
711 reaper = find_new_reaper(father, child_reaper: reaper);
712 list_for_each_entry(p, &father->children, sibling) {
713 for_each_thread(p, t) {
714 RCU_INIT_POINTER(t->real_parent, reaper);
715 BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father));
716 if (likely(!t->ptrace))
717 t->parent = t->real_parent;
718 if (t->pdeath_signal)
719 group_send_sig_info(sig: t->pdeath_signal,
720 SEND_SIG_NOINFO, p: t,
721 type: PIDTYPE_TGID);
722 }
723 /*
724 * If this is a threaded reparent there is no need to
725 * notify anyone anything has happened.
726 */
727 if (!same_thread_group(p1: reaper, p2: father))
728 reparent_leader(father, p, dead);
729 }
730 list_splice_tail_init(list: &father->children, head: &reaper->children);
731}
732
733/*
734 * Send signals to all our closest relatives so that they know
735 * to properly mourn us..
736 */
737static void exit_notify(struct task_struct *tsk, int group_dead)
738{
739 bool autoreap;
740 struct task_struct *p, *n;
741 LIST_HEAD(dead);
742
743 write_lock_irq(&tasklist_lock);
744 forget_original_parent(father: tsk, dead: &dead);
745
746 if (group_dead)
747 kill_orphaned_pgrp(tsk: tsk->group_leader, NULL);
748
749 tsk->exit_state = EXIT_ZOMBIE;
750
751 if (unlikely(tsk->ptrace)) {
752 int sig = thread_group_leader(p: tsk) &&
753 thread_group_empty(p: tsk) &&
754 !ptrace_reparented(child: tsk) ?
755 tsk->exit_signal : SIGCHLD;
756 autoreap = do_notify_parent(tsk, sig);
757 } else if (thread_group_leader(p: tsk)) {
758 autoreap = thread_group_empty(p: tsk) &&
759 do_notify_parent(tsk, tsk->exit_signal);
760 } else {
761 autoreap = true;
762 /* untraced sub-thread */
763 do_notify_pidfd(task: tsk);
764 }
765
766 if (autoreap) {
767 tsk->exit_state = EXIT_DEAD;
768 list_add(new: &tsk->ptrace_entry, head: &dead);
769 }
770
771 /* mt-exec, de_thread() is waiting for group leader */
772 if (unlikely(tsk->signal->notify_count < 0))
773 wake_up_process(tsk: tsk->signal->group_exec_task);
774 write_unlock_irq(&tasklist_lock);
775
776 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
777 list_del_init(entry: &p->ptrace_entry);
778 release_task(p);
779 }
780}
781
782#ifdef CONFIG_DEBUG_STACK_USAGE
783#ifdef CONFIG_STACK_GROWSUP
784unsigned long stack_not_used(struct task_struct *p)
785{
786 unsigned long *n = end_of_stack(p);
787
788 do { /* Skip over canary */
789 n--;
790 } while (!*n);
791
792 return (unsigned long)end_of_stack(p) - (unsigned long)n;
793}
794#else /* !CONFIG_STACK_GROWSUP */
795unsigned long stack_not_used(struct task_struct *p)
796{
797 unsigned long *n = end_of_stack(task: p);
798
799 do { /* Skip over canary */
800 n++;
801 } while (!*n);
802
803 return (unsigned long)n - (unsigned long)end_of_stack(task: p);
804}
805#endif /* CONFIG_STACK_GROWSUP */
806
807/* Count the maximum pages reached in kernel stacks */
808static inline void kstack_histogram(unsigned long used_stack)
809{
810#ifdef CONFIG_VM_EVENT_COUNTERS
811 if (used_stack <= 1024)
812 count_vm_event(item: KSTACK_1K);
813#if THREAD_SIZE > 1024
814 else if (used_stack <= 2048)
815 count_vm_event(item: KSTACK_2K);
816#endif
817#if THREAD_SIZE > 2048
818 else if (used_stack <= 4096)
819 count_vm_event(item: KSTACK_4K);
820#endif
821#if THREAD_SIZE > 4096
822 else if (used_stack <= 8192)
823 count_vm_event(item: KSTACK_8K);
824#endif
825#if THREAD_SIZE > 8192
826 else if (used_stack <= 16384)
827 count_vm_event(item: KSTACK_16K);
828#endif
829#if THREAD_SIZE > 16384
830 else if (used_stack <= 32768)
831 count_vm_event(KSTACK_32K);
832#endif
833#if THREAD_SIZE > 32768
834 else if (used_stack <= 65536)
835 count_vm_event(KSTACK_64K);
836#endif
837#if THREAD_SIZE > 65536
838 else
839 count_vm_event(KSTACK_REST);
840#endif
841#endif /* CONFIG_VM_EVENT_COUNTERS */
842}
843
844static void check_stack_usage(void)
845{
846 static DEFINE_SPINLOCK(low_water_lock);
847 static int lowest_to_date = THREAD_SIZE;
848 unsigned long free;
849
850 free = stack_not_used(current);
851 kstack_histogram(THREAD_SIZE - free);
852
853 if (free >= lowest_to_date)
854 return;
855
856 spin_lock(lock: &low_water_lock);
857 if (free < lowest_to_date) {
858 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
859 current->comm, task_pid_nr(current), free);
860 lowest_to_date = free;
861 }
862 spin_unlock(lock: &low_water_lock);
863}
864#else /* !CONFIG_DEBUG_STACK_USAGE */
865static inline void check_stack_usage(void) {}
866#endif /* CONFIG_DEBUG_STACK_USAGE */
867
868static void synchronize_group_exit(struct task_struct *tsk, long code)
869{
870 struct sighand_struct *sighand = tsk->sighand;
871 struct signal_struct *signal = tsk->signal;
872 struct core_state *core_state;
873
874 spin_lock_irq(lock: &sighand->siglock);
875 signal->quick_threads--;
876 if ((signal->quick_threads == 0) &&
877 !(signal->flags & SIGNAL_GROUP_EXIT)) {
878 signal->flags = SIGNAL_GROUP_EXIT;
879 signal->group_exit_code = code;
880 signal->group_stop_count = 0;
881 }
882 /*
883 * Serialize with any possible pending coredump.
884 * We must hold siglock around checking core_state
885 * and setting PF_POSTCOREDUMP. The core-inducing thread
886 * will increment ->nr_threads for each thread in the
887 * group without PF_POSTCOREDUMP set.
888 */
889 tsk->flags |= PF_POSTCOREDUMP;
890 core_state = signal->core_state;
891 spin_unlock_irq(lock: &sighand->siglock);
892
893 if (unlikely(core_state))
894 coredump_task_exit(tsk, core_state);
895}
896
897void __noreturn do_exit(long code)
898{
899 struct task_struct *tsk = current;
900 int group_dead;
901
902 WARN_ON(irqs_disabled());
903 WARN_ON(tsk->plug);
904
905 kcov_task_exit(t: tsk);
906 kmsan_task_exit(task: tsk);
907
908 synchronize_group_exit(tsk, code);
909 ptrace_event(PTRACE_EVENT_EXIT, message: code);
910 user_events_exit(t: tsk);
911
912 io_uring_files_cancel();
913 exit_signals(tsk); /* sets PF_EXITING */
914
915 seccomp_filter_release(tsk);
916
917 acct_update_integrals(tsk);
918 group_dead = atomic_dec_and_test(v: &tsk->signal->live);
919 if (group_dead) {
920 /*
921 * If the last thread of global init has exited, panic
922 * immediately to get a useable coredump.
923 */
924 if (unlikely(is_global_init(tsk)))
925 panic(fmt: "Attempted to kill init! exitcode=0x%08x\n",
926 tsk->signal->group_exit_code ?: (int)code);
927
928#ifdef CONFIG_POSIX_TIMERS
929 hrtimer_cancel(timer: &tsk->signal->real_timer);
930 exit_itimers(tsk);
931#endif
932 if (tsk->mm)
933 setmax_mm_hiwater_rss(maxrss: &tsk->signal->maxrss, mm: tsk->mm);
934 }
935 acct_collect(exitcode: code, group_dead);
936 if (group_dead)
937 tty_audit_exit();
938 audit_free(task: tsk);
939
940 tsk->exit_code = code;
941 taskstats_exit(tsk, group_dead);
942 unwind_deferred_task_exit(task: tsk);
943 trace_sched_process_exit(p: tsk, group_dead);
944
945 /*
946 * Since sampling can touch ->mm, make sure to stop everything before we
947 * tear it down.
948 *
949 * Also flushes inherited counters to the parent - before the parent
950 * gets woken up by child-exit notifications.
951 */
952 perf_event_exit_task(child: tsk);
953
954 exit_mm();
955
956 if (group_dead)
957 acct_process();
958
959 exit_sem(tsk);
960 exit_shm(task: tsk);
961 exit_files(tsk);
962 exit_fs(tsk);
963 if (group_dead)
964 disassociate_ctty(priv: 1);
965 exit_task_namespaces(tsk);
966 exit_task_work(task: tsk);
967 exit_thread(tsk);
968
969 sched_autogroup_exit_task(p: tsk);
970 cgroup_exit(p: tsk);
971
972 /*
973 * FIXME: do that only when needed, using sched_exit tracepoint
974 */
975 flush_ptrace_hw_breakpoint(tsk);
976
977 exit_tasks_rcu_start();
978 exit_notify(tsk, group_dead);
979 proc_exit_connector(task: tsk);
980 mpol_put_task_policy(tsk);
981#ifdef CONFIG_FUTEX
982 if (unlikely(current->pi_state_cache))
983 kfree(current->pi_state_cache);
984#endif
985 /*
986 * Make sure we are holding no locks:
987 */
988 debug_check_no_locks_held();
989
990 if (tsk->io_context)
991 exit_io_context(task: tsk);
992
993 if (tsk->splice_pipe)
994 free_pipe_info(tsk->splice_pipe);
995
996 if (tsk->task_frag.page)
997 put_page(page: tsk->task_frag.page);
998
999 exit_task_stack_account(tsk);
1000
1001 check_stack_usage();
1002 preempt_disable();
1003 if (tsk->nr_dirtied)
1004 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
1005 exit_rcu();
1006 exit_tasks_rcu_finish();
1007
1008 lockdep_free_task(task: tsk);
1009 do_task_dead();
1010}
1011
1012void __noreturn make_task_dead(int signr)
1013{
1014 /*
1015 * Take the task off the cpu after something catastrophic has
1016 * happened.
1017 *
1018 * We can get here from a kernel oops, sometimes with preemption off.
1019 * Start by checking for critical errors.
1020 * Then fix up important state like USER_DS and preemption.
1021 * Then do everything else.
1022 */
1023 struct task_struct *tsk = current;
1024 unsigned int limit;
1025
1026 if (unlikely(in_interrupt()))
1027 panic(fmt: "Aiee, killing interrupt handler!");
1028 if (unlikely(!tsk->pid))
1029 panic(fmt: "Attempted to kill the idle task!");
1030
1031 if (unlikely(irqs_disabled())) {
1032 pr_info("note: %s[%d] exited with irqs disabled\n",
1033 current->comm, task_pid_nr(current));
1034 local_irq_enable();
1035 }
1036 if (unlikely(in_atomic())) {
1037 pr_info("note: %s[%d] exited with preempt_count %d\n",
1038 current->comm, task_pid_nr(current),
1039 preempt_count());
1040 preempt_count_set(PREEMPT_ENABLED);
1041 }
1042
1043 /*
1044 * Every time the system oopses, if the oops happens while a reference
1045 * to an object was held, the reference leaks.
1046 * If the oops doesn't also leak memory, repeated oopsing can cause
1047 * reference counters to wrap around (if they're not using refcount_t).
1048 * This means that repeated oopsing can make unexploitable-looking bugs
1049 * exploitable through repeated oopsing.
1050 * To make sure this can't happen, place an upper bound on how often the
1051 * kernel may oops without panic().
1052 */
1053 limit = READ_ONCE(oops_limit);
1054 if (atomic_inc_return(v: &oops_count) >= limit && limit)
1055 panic(fmt: "Oopsed too often (kernel.oops_limit is %d)", limit);
1056
1057 /*
1058 * We're taking recursive faults here in make_task_dead. Safest is to just
1059 * leave this task alone and wait for reboot.
1060 */
1061 if (unlikely(tsk->flags & PF_EXITING)) {
1062 pr_alert("Fixing recursive fault but reboot is needed!\n");
1063 futex_exit_recursive(tsk);
1064 tsk->exit_state = EXIT_DEAD;
1065 refcount_inc(r: &tsk->rcu_users);
1066 do_task_dead();
1067 }
1068
1069 do_exit(code: signr);
1070}
1071
1072SYSCALL_DEFINE1(exit, int, error_code)
1073{
1074 do_exit(code: (error_code&0xff)<<8);
1075}
1076
1077/*
1078 * Take down every thread in the group. This is called by fatal signals
1079 * as well as by sys_exit_group (below).
1080 */
1081void __noreturn
1082do_group_exit(int exit_code)
1083{
1084 struct signal_struct *sig = current->signal;
1085
1086 if (sig->flags & SIGNAL_GROUP_EXIT)
1087 exit_code = sig->group_exit_code;
1088 else if (sig->group_exec_task)
1089 exit_code = 0;
1090 else {
1091 struct sighand_struct *const sighand = current->sighand;
1092
1093 spin_lock_irq(lock: &sighand->siglock);
1094 if (sig->flags & SIGNAL_GROUP_EXIT)
1095 /* Another thread got here before we took the lock. */
1096 exit_code = sig->group_exit_code;
1097 else if (sig->group_exec_task)
1098 exit_code = 0;
1099 else {
1100 sig->group_exit_code = exit_code;
1101 sig->flags = SIGNAL_GROUP_EXIT;
1102 zap_other_threads(current);
1103 }
1104 spin_unlock_irq(lock: &sighand->siglock);
1105 }
1106
1107 do_exit(code: exit_code);
1108 /* NOTREACHED */
1109}
1110
1111/*
1112 * this kills every thread in the thread group. Note that any externally
1113 * wait4()-ing process will get the correct exit code - even if this
1114 * thread is not the thread group leader.
1115 */
1116SYSCALL_DEFINE1(exit_group, int, error_code)
1117{
1118 do_group_exit(exit_code: (error_code & 0xff) << 8);
1119 /* NOTREACHED */
1120 return 0;
1121}
1122
1123static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1124{
1125 return wo->wo_type == PIDTYPE_MAX ||
1126 task_pid_type(task: p, type: wo->wo_type) == wo->wo_pid;
1127}
1128
1129static int
1130eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
1131{
1132 if (!eligible_pid(wo, p))
1133 return 0;
1134
1135 /*
1136 * Wait for all children (clone and not) if __WALL is set or
1137 * if it is traced by us.
1138 */
1139 if (ptrace || (wo->wo_flags & __WALL))
1140 return 1;
1141
1142 /*
1143 * Otherwise, wait for clone children *only* if __WCLONE is set;
1144 * otherwise, wait for non-clone children *only*.
1145 *
1146 * Note: a "clone" child here is one that reports to its parent
1147 * using a signal other than SIGCHLD, or a non-leader thread which
1148 * we can only see if it is traced by us.
1149 */
1150 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1151 return 0;
1152
1153 return 1;
1154}
1155
1156/*
1157 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1158 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1159 * the lock and this task is uninteresting. If we return nonzero, we have
1160 * released the lock and the system call should return.
1161 */
1162static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1163{
1164 int state, status;
1165 pid_t pid = task_pid_vnr(tsk: p);
1166 uid_t uid = from_kuid_munged(to: current_user_ns(), task_uid(p));
1167 struct waitid_info *infop;
1168
1169 if (!likely(wo->wo_flags & WEXITED))
1170 return 0;
1171
1172 if (unlikely(wo->wo_flags & WNOWAIT)) {
1173 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1174 ? p->signal->group_exit_code : p->exit_code;
1175 get_task_struct(t: p);
1176 read_unlock(&tasklist_lock);
1177 sched_annotate_sleep();
1178 if (wo->wo_rusage)
1179 getrusage(p, RUSAGE_BOTH, ru: wo->wo_rusage);
1180 put_task_struct(t: p);
1181 goto out_info;
1182 }
1183 /*
1184 * Move the task's state to DEAD/TRACE, only one thread can do this.
1185 */
1186 state = (ptrace_reparented(child: p) && thread_group_leader(p)) ?
1187 EXIT_TRACE : EXIT_DEAD;
1188 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1189 return 0;
1190 /*
1191 * We own this thread, nobody else can reap it.
1192 */
1193 read_unlock(&tasklist_lock);
1194 sched_annotate_sleep();
1195
1196 /*
1197 * Check thread_group_leader() to exclude the traced sub-threads.
1198 */
1199 if (state == EXIT_DEAD && thread_group_leader(p)) {
1200 struct signal_struct *sig = p->signal;
1201 struct signal_struct *psig = current->signal;
1202 unsigned long maxrss;
1203 u64 tgutime, tgstime;
1204
1205 /*
1206 * The resource counters for the group leader are in its
1207 * own task_struct. Those for dead threads in the group
1208 * are in its signal_struct, as are those for the child
1209 * processes it has previously reaped. All these
1210 * accumulate in the parent's signal_struct c* fields.
1211 *
1212 * We don't bother to take a lock here to protect these
1213 * p->signal fields because the whole thread group is dead
1214 * and nobody can change them.
1215 *
1216 * psig->stats_lock also protects us from our sub-threads
1217 * which can reap other children at the same time.
1218 *
1219 * We use thread_group_cputime_adjusted() to get times for
1220 * the thread group, which consolidates times for all threads
1221 * in the group including the group leader.
1222 */
1223 thread_group_cputime_adjusted(p, ut: &tgutime, st: &tgstime);
1224 write_seqlock_irq(sl: &psig->stats_lock);
1225 psig->cutime += tgutime + sig->cutime;
1226 psig->cstime += tgstime + sig->cstime;
1227 psig->cgtime += task_gtime(t: p) + sig->gtime + sig->cgtime;
1228 psig->cmin_flt +=
1229 p->min_flt + sig->min_flt + sig->cmin_flt;
1230 psig->cmaj_flt +=
1231 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1232 psig->cnvcsw +=
1233 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1234 psig->cnivcsw +=
1235 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1236 psig->cinblock +=
1237 task_io_get_inblock(p) +
1238 sig->inblock + sig->cinblock;
1239 psig->coublock +=
1240 task_io_get_oublock(p) +
1241 sig->oublock + sig->coublock;
1242 maxrss = max(sig->maxrss, sig->cmaxrss);
1243 if (psig->cmaxrss < maxrss)
1244 psig->cmaxrss = maxrss;
1245 task_io_accounting_add(dst: &psig->ioac, src: &p->ioac);
1246 task_io_accounting_add(dst: &psig->ioac, src: &sig->ioac);
1247 write_sequnlock_irq(sl: &psig->stats_lock);
1248 }
1249
1250 if (wo->wo_rusage)
1251 getrusage(p, RUSAGE_BOTH, ru: wo->wo_rusage);
1252 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1253 ? p->signal->group_exit_code : p->exit_code;
1254 wo->wo_stat = status;
1255
1256 if (state == EXIT_TRACE) {
1257 write_lock_irq(&tasklist_lock);
1258 /* We dropped tasklist, ptracer could die and untrace */
1259 ptrace_unlink(child: p);
1260
1261 /* If parent wants a zombie, don't release it now */
1262 state = EXIT_ZOMBIE;
1263 if (do_notify_parent(p, p->exit_signal))
1264 state = EXIT_DEAD;
1265 p->exit_state = state;
1266 write_unlock_irq(&tasklist_lock);
1267 }
1268 if (state == EXIT_DEAD)
1269 release_task(p);
1270
1271out_info:
1272 infop = wo->wo_info;
1273 if (infop) {
1274 if ((status & 0x7f) == 0) {
1275 infop->cause = CLD_EXITED;
1276 infop->status = status >> 8;
1277 } else {
1278 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1279 infop->status = status & 0x7f;
1280 }
1281 infop->pid = pid;
1282 infop->uid = uid;
1283 }
1284
1285 return pid;
1286}
1287
1288static int *task_stopped_code(struct task_struct *p, bool ptrace)
1289{
1290 if (ptrace) {
1291 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1292 return &p->exit_code;
1293 } else {
1294 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1295 return &p->signal->group_exit_code;
1296 }
1297 return NULL;
1298}
1299
1300/**
1301 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1302 * @wo: wait options
1303 * @ptrace: is the wait for ptrace
1304 * @p: task to wait for
1305 *
1306 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1307 *
1308 * CONTEXT:
1309 * read_lock(&tasklist_lock), which is released if return value is
1310 * non-zero. Also, grabs and releases @p->sighand->siglock.
1311 *
1312 * RETURNS:
1313 * 0 if wait condition didn't exist and search for other wait conditions
1314 * should continue. Non-zero return, -errno on failure and @p's pid on
1315 * success, implies that tasklist_lock is released and wait condition
1316 * search should terminate.
1317 */
1318static int wait_task_stopped(struct wait_opts *wo,
1319 int ptrace, struct task_struct *p)
1320{
1321 struct waitid_info *infop;
1322 int exit_code, *p_code, why;
1323 uid_t uid = 0; /* unneeded, required by compiler */
1324 pid_t pid;
1325
1326 /*
1327 * Traditionally we see ptrace'd stopped tasks regardless of options.
1328 */
1329 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1330 return 0;
1331
1332 if (!task_stopped_code(p, ptrace))
1333 return 0;
1334
1335 exit_code = 0;
1336 spin_lock_irq(lock: &p->sighand->siglock);
1337
1338 p_code = task_stopped_code(p, ptrace);
1339 if (unlikely(!p_code))
1340 goto unlock_sig;
1341
1342 exit_code = *p_code;
1343 if (!exit_code)
1344 goto unlock_sig;
1345
1346 if (!unlikely(wo->wo_flags & WNOWAIT))
1347 *p_code = 0;
1348
1349 uid = from_kuid_munged(to: current_user_ns(), task_uid(p));
1350unlock_sig:
1351 spin_unlock_irq(lock: &p->sighand->siglock);
1352 if (!exit_code)
1353 return 0;
1354
1355 /*
1356 * Now we are pretty sure this task is interesting.
1357 * Make sure it doesn't get reaped out from under us while we
1358 * give up the lock and then examine it below. We don't want to
1359 * keep holding onto the tasklist_lock while we call getrusage and
1360 * possibly take page faults for user memory.
1361 */
1362 get_task_struct(t: p);
1363 pid = task_pid_vnr(tsk: p);
1364 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1365 read_unlock(&tasklist_lock);
1366 sched_annotate_sleep();
1367 if (wo->wo_rusage)
1368 getrusage(p, RUSAGE_BOTH, ru: wo->wo_rusage);
1369 put_task_struct(t: p);
1370
1371 if (likely(!(wo->wo_flags & WNOWAIT)))
1372 wo->wo_stat = (exit_code << 8) | 0x7f;
1373
1374 infop = wo->wo_info;
1375 if (infop) {
1376 infop->cause = why;
1377 infop->status = exit_code;
1378 infop->pid = pid;
1379 infop->uid = uid;
1380 }
1381 return pid;
1382}
1383
1384/*
1385 * Handle do_wait work for one task in a live, non-stopped state.
1386 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1387 * the lock and this task is uninteresting. If we return nonzero, we have
1388 * released the lock and the system call should return.
1389 */
1390static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1391{
1392 struct waitid_info *infop;
1393 pid_t pid;
1394 uid_t uid;
1395
1396 if (!unlikely(wo->wo_flags & WCONTINUED))
1397 return 0;
1398
1399 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1400 return 0;
1401
1402 spin_lock_irq(lock: &p->sighand->siglock);
1403 /* Re-check with the lock held. */
1404 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1405 spin_unlock_irq(lock: &p->sighand->siglock);
1406 return 0;
1407 }
1408 if (!unlikely(wo->wo_flags & WNOWAIT))
1409 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1410 uid = from_kuid_munged(to: current_user_ns(), task_uid(p));
1411 spin_unlock_irq(lock: &p->sighand->siglock);
1412
1413 pid = task_pid_vnr(tsk: p);
1414 get_task_struct(t: p);
1415 read_unlock(&tasklist_lock);
1416 sched_annotate_sleep();
1417 if (wo->wo_rusage)
1418 getrusage(p, RUSAGE_BOTH, ru: wo->wo_rusage);
1419 put_task_struct(t: p);
1420
1421 infop = wo->wo_info;
1422 if (!infop) {
1423 wo->wo_stat = 0xffff;
1424 } else {
1425 infop->cause = CLD_CONTINUED;
1426 infop->pid = pid;
1427 infop->uid = uid;
1428 infop->status = SIGCONT;
1429 }
1430 return pid;
1431}
1432
1433/*
1434 * Consider @p for a wait by @parent.
1435 *
1436 * -ECHILD should be in ->notask_error before the first call.
1437 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1438 * Returns zero if the search for a child should continue;
1439 * then ->notask_error is 0 if @p is an eligible child,
1440 * or still -ECHILD.
1441 */
1442static int wait_consider_task(struct wait_opts *wo, int ptrace,
1443 struct task_struct *p)
1444{
1445 /*
1446 * We can race with wait_task_zombie() from another thread.
1447 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1448 * can't confuse the checks below.
1449 */
1450 int exit_state = READ_ONCE(p->exit_state);
1451 int ret;
1452
1453 if (unlikely(exit_state == EXIT_DEAD))
1454 return 0;
1455
1456 ret = eligible_child(wo, ptrace, p);
1457 if (!ret)
1458 return ret;
1459
1460 if (unlikely(exit_state == EXIT_TRACE)) {
1461 /*
1462 * ptrace == 0 means we are the natural parent. In this case
1463 * we should clear notask_error, debugger will notify us.
1464 */
1465 if (likely(!ptrace))
1466 wo->notask_error = 0;
1467 return 0;
1468 }
1469
1470 if (likely(!ptrace) && unlikely(p->ptrace)) {
1471 /*
1472 * If it is traced by its real parent's group, just pretend
1473 * the caller is ptrace_do_wait() and reap this child if it
1474 * is zombie.
1475 *
1476 * This also hides group stop state from real parent; otherwise
1477 * a single stop can be reported twice as group and ptrace stop.
1478 * If a ptracer wants to distinguish these two events for its
1479 * own children it should create a separate process which takes
1480 * the role of real parent.
1481 */
1482 if (!ptrace_reparented(child: p))
1483 ptrace = 1;
1484 }
1485
1486 /* slay zombie? */
1487 if (exit_state == EXIT_ZOMBIE) {
1488 /* we don't reap group leaders with subthreads */
1489 if (!delay_group_leader(p)) {
1490 /*
1491 * A zombie ptracee is only visible to its ptracer.
1492 * Notification and reaping will be cascaded to the
1493 * real parent when the ptracer detaches.
1494 */
1495 if (unlikely(ptrace) || likely(!p->ptrace))
1496 return wait_task_zombie(wo, p);
1497 }
1498
1499 /*
1500 * Allow access to stopped/continued state via zombie by
1501 * falling through. Clearing of notask_error is complex.
1502 *
1503 * When !@ptrace:
1504 *
1505 * If WEXITED is set, notask_error should naturally be
1506 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1507 * so, if there are live subthreads, there are events to
1508 * wait for. If all subthreads are dead, it's still safe
1509 * to clear - this function will be called again in finite
1510 * amount time once all the subthreads are released and
1511 * will then return without clearing.
1512 *
1513 * When @ptrace:
1514 *
1515 * Stopped state is per-task and thus can't change once the
1516 * target task dies. Only continued and exited can happen.
1517 * Clear notask_error if WCONTINUED | WEXITED.
1518 */
1519 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1520 wo->notask_error = 0;
1521 } else {
1522 /*
1523 * @p is alive and it's gonna stop, continue or exit, so
1524 * there always is something to wait for.
1525 */
1526 wo->notask_error = 0;
1527 }
1528
1529 /*
1530 * Wait for stopped. Depending on @ptrace, different stopped state
1531 * is used and the two don't interact with each other.
1532 */
1533 ret = wait_task_stopped(wo, ptrace, p);
1534 if (ret)
1535 return ret;
1536
1537 /*
1538 * Wait for continued. There's only one continued state and the
1539 * ptracer can consume it which can confuse the real parent. Don't
1540 * use WCONTINUED from ptracer. You don't need or want it.
1541 */
1542 return wait_task_continued(wo, p);
1543}
1544
1545/*
1546 * Do the work of do_wait() for one thread in the group, @tsk.
1547 *
1548 * -ECHILD should be in ->notask_error before the first call.
1549 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1550 * Returns zero if the search for a child should continue; then
1551 * ->notask_error is 0 if there were any eligible children,
1552 * or still -ECHILD.
1553 */
1554static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1555{
1556 struct task_struct *p;
1557
1558 list_for_each_entry(p, &tsk->children, sibling) {
1559 int ret = wait_consider_task(wo, ptrace: 0, p);
1560
1561 if (ret)
1562 return ret;
1563 }
1564
1565 return 0;
1566}
1567
1568static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1569{
1570 struct task_struct *p;
1571
1572 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1573 int ret = wait_consider_task(wo, ptrace: 1, p);
1574
1575 if (ret)
1576 return ret;
1577 }
1578
1579 return 0;
1580}
1581
1582bool pid_child_should_wake(struct wait_opts *wo, struct task_struct *p)
1583{
1584 if (!eligible_pid(wo, p))
1585 return false;
1586
1587 if ((wo->wo_flags & __WNOTHREAD) && wo->child_wait.private != p->parent)
1588 return false;
1589
1590 return true;
1591}
1592
1593static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1594 int sync, void *key)
1595{
1596 struct wait_opts *wo = container_of(wait, struct wait_opts,
1597 child_wait);
1598 struct task_struct *p = key;
1599
1600 if (pid_child_should_wake(wo, p))
1601 return default_wake_function(wq_entry: wait, mode, flags: sync, key);
1602
1603 return 0;
1604}
1605
1606void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1607{
1608 __wake_up_sync_key(wq_head: &parent->signal->wait_chldexit,
1609 TASK_INTERRUPTIBLE, key: p);
1610}
1611
1612static bool is_effectively_child(struct wait_opts *wo, bool ptrace,
1613 struct task_struct *target)
1614{
1615 struct task_struct *parent =
1616 !ptrace ? target->real_parent : target->parent;
1617
1618 return current == parent || (!(wo->wo_flags & __WNOTHREAD) &&
1619 same_thread_group(current, p2: parent));
1620}
1621
1622/*
1623 * Optimization for waiting on PIDTYPE_PID. No need to iterate through child
1624 * and tracee lists to find the target task.
1625 */
1626static int do_wait_pid(struct wait_opts *wo)
1627{
1628 bool ptrace;
1629 struct task_struct *target;
1630 int retval;
1631
1632 ptrace = false;
1633 target = pid_task(pid: wo->wo_pid, PIDTYPE_TGID);
1634 if (target && is_effectively_child(wo, ptrace, target)) {
1635 retval = wait_consider_task(wo, ptrace, p: target);
1636 if (retval)
1637 return retval;
1638 }
1639
1640 ptrace = true;
1641 target = pid_task(pid: wo->wo_pid, PIDTYPE_PID);
1642 if (target && target->ptrace &&
1643 is_effectively_child(wo, ptrace, target)) {
1644 retval = wait_consider_task(wo, ptrace, p: target);
1645 if (retval)
1646 return retval;
1647 }
1648
1649 return 0;
1650}
1651
1652long __do_wait(struct wait_opts *wo)
1653{
1654 long retval;
1655
1656 /*
1657 * If there is nothing that can match our criteria, just get out.
1658 * We will clear ->notask_error to zero if we see any child that
1659 * might later match our criteria, even if we are not able to reap
1660 * it yet.
1661 */
1662 wo->notask_error = -ECHILD;
1663 if ((wo->wo_type < PIDTYPE_MAX) &&
1664 (!wo->wo_pid || !pid_has_task(pid: wo->wo_pid, type: wo->wo_type)))
1665 goto notask;
1666
1667 read_lock(&tasklist_lock);
1668
1669 if (wo->wo_type == PIDTYPE_PID) {
1670 retval = do_wait_pid(wo);
1671 if (retval)
1672 return retval;
1673 } else {
1674 struct task_struct *tsk = current;
1675
1676 do {
1677 retval = do_wait_thread(wo, tsk);
1678 if (retval)
1679 return retval;
1680
1681 retval = ptrace_do_wait(wo, tsk);
1682 if (retval)
1683 return retval;
1684
1685 if (wo->wo_flags & __WNOTHREAD)
1686 break;
1687 } while_each_thread(current, tsk);
1688 }
1689 read_unlock(&tasklist_lock);
1690
1691notask:
1692 retval = wo->notask_error;
1693 if (!retval && !(wo->wo_flags & WNOHANG))
1694 return -ERESTARTSYS;
1695
1696 return retval;
1697}
1698
1699static long do_wait(struct wait_opts *wo)
1700{
1701 int retval;
1702
1703 trace_sched_process_wait(pid: wo->wo_pid);
1704
1705 init_waitqueue_func_entry(wq_entry: &wo->child_wait, func: child_wait_callback);
1706 wo->child_wait.private = current;
1707 add_wait_queue(wq_head: &current->signal->wait_chldexit, wq_entry: &wo->child_wait);
1708
1709 do {
1710 set_current_state(TASK_INTERRUPTIBLE);
1711 retval = __do_wait(wo);
1712 if (retval != -ERESTARTSYS)
1713 break;
1714 if (signal_pending(current))
1715 break;
1716 schedule();
1717 } while (1);
1718
1719 __set_current_state(TASK_RUNNING);
1720 remove_wait_queue(wq_head: &current->signal->wait_chldexit, wq_entry: &wo->child_wait);
1721 return retval;
1722}
1723
1724int kernel_waitid_prepare(struct wait_opts *wo, int which, pid_t upid,
1725 struct waitid_info *infop, int options,
1726 struct rusage *ru)
1727{
1728 unsigned int f_flags = 0;
1729 struct pid *pid = NULL;
1730 enum pid_type type;
1731
1732 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1733 __WNOTHREAD|__WCLONE|__WALL))
1734 return -EINVAL;
1735 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1736 return -EINVAL;
1737
1738 switch (which) {
1739 case P_ALL:
1740 type = PIDTYPE_MAX;
1741 break;
1742 case P_PID:
1743 type = PIDTYPE_PID;
1744 if (upid <= 0)
1745 return -EINVAL;
1746
1747 pid = find_get_pid(nr: upid);
1748 break;
1749 case P_PGID:
1750 type = PIDTYPE_PGID;
1751 if (upid < 0)
1752 return -EINVAL;
1753
1754 if (upid)
1755 pid = find_get_pid(nr: upid);
1756 else
1757 pid = get_task_pid(current, type: PIDTYPE_PGID);
1758 break;
1759 case P_PIDFD:
1760 type = PIDTYPE_PID;
1761 if (upid < 0)
1762 return -EINVAL;
1763
1764 pid = pidfd_get_pid(fd: upid, flags: &f_flags);
1765 if (IS_ERR(ptr: pid))
1766 return PTR_ERR(ptr: pid);
1767
1768 break;
1769 default:
1770 return -EINVAL;
1771 }
1772
1773 wo->wo_type = type;
1774 wo->wo_pid = pid;
1775 wo->wo_flags = options;
1776 wo->wo_info = infop;
1777 wo->wo_rusage = ru;
1778 if (f_flags & O_NONBLOCK)
1779 wo->wo_flags |= WNOHANG;
1780
1781 return 0;
1782}
1783
1784static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1785 int options, struct rusage *ru)
1786{
1787 struct wait_opts wo;
1788 long ret;
1789
1790 ret = kernel_waitid_prepare(wo: &wo, which, upid, infop, options, ru);
1791 if (ret)
1792 return ret;
1793
1794 ret = do_wait(wo: &wo);
1795 if (!ret && !(options & WNOHANG) && (wo.wo_flags & WNOHANG))
1796 ret = -EAGAIN;
1797
1798 put_pid(pid: wo.wo_pid);
1799 return ret;
1800}
1801
1802SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1803 infop, int, options, struct rusage __user *, ru)
1804{
1805 struct rusage r;
1806 struct waitid_info info = {.status = 0};
1807 long err = kernel_waitid(which, upid, infop: &info, options, ru: ru ? &r : NULL);
1808 int signo = 0;
1809
1810 if (err > 0) {
1811 signo = SIGCHLD;
1812 err = 0;
1813 if (ru && copy_to_user(to: ru, from: &r, n: sizeof(struct rusage)))
1814 return -EFAULT;
1815 }
1816 if (!infop)
1817 return err;
1818
1819 if (!user_write_access_begin(infop, sizeof(*infop)))
1820 return -EFAULT;
1821
1822 unsafe_put_user(signo, &infop->si_signo, Efault);
1823 unsafe_put_user(0, &infop->si_errno, Efault);
1824 unsafe_put_user(info.cause, &infop->si_code, Efault);
1825 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1826 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1827 unsafe_put_user(info.status, &infop->si_status, Efault);
1828 user_write_access_end();
1829 return err;
1830Efault:
1831 user_write_access_end();
1832 return -EFAULT;
1833}
1834
1835long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1836 struct rusage *ru)
1837{
1838 struct wait_opts wo;
1839 struct pid *pid = NULL;
1840 enum pid_type type;
1841 long ret;
1842
1843 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1844 __WNOTHREAD|__WCLONE|__WALL))
1845 return -EINVAL;
1846
1847 /* -INT_MIN is not defined */
1848 if (upid == INT_MIN)
1849 return -ESRCH;
1850
1851 if (upid == -1)
1852 type = PIDTYPE_MAX;
1853 else if (upid < 0) {
1854 type = PIDTYPE_PGID;
1855 pid = find_get_pid(nr: -upid);
1856 } else if (upid == 0) {
1857 type = PIDTYPE_PGID;
1858 pid = get_task_pid(current, type: PIDTYPE_PGID);
1859 } else /* upid > 0 */ {
1860 type = PIDTYPE_PID;
1861 pid = find_get_pid(nr: upid);
1862 }
1863
1864 wo.wo_type = type;
1865 wo.wo_pid = pid;
1866 wo.wo_flags = options | WEXITED;
1867 wo.wo_info = NULL;
1868 wo.wo_stat = 0;
1869 wo.wo_rusage = ru;
1870 ret = do_wait(wo: &wo);
1871 put_pid(pid);
1872 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1873 ret = -EFAULT;
1874
1875 return ret;
1876}
1877
1878int kernel_wait(pid_t pid, int *stat)
1879{
1880 struct wait_opts wo = {
1881 .wo_type = PIDTYPE_PID,
1882 .wo_pid = find_get_pid(nr: pid),
1883 .wo_flags = WEXITED,
1884 };
1885 int ret;
1886
1887 ret = do_wait(wo: &wo);
1888 if (ret > 0 && wo.wo_stat)
1889 *stat = wo.wo_stat;
1890 put_pid(pid: wo.wo_pid);
1891 return ret;
1892}
1893
1894SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1895 int, options, struct rusage __user *, ru)
1896{
1897 struct rusage r;
1898 long err = kernel_wait4(upid, stat_addr, options, ru: ru ? &r : NULL);
1899
1900 if (err > 0) {
1901 if (ru && copy_to_user(to: ru, from: &r, n: sizeof(struct rusage)))
1902 return -EFAULT;
1903 }
1904 return err;
1905}
1906
1907#ifdef __ARCH_WANT_SYS_WAITPID
1908
1909/*
1910 * sys_waitpid() remains for compatibility. waitpid() should be
1911 * implemented by calling sys_wait4() from libc.a.
1912 */
1913SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1914{
1915 return kernel_wait4(upid: pid, stat_addr, options, NULL);
1916}
1917
1918#endif
1919
1920#ifdef CONFIG_COMPAT
1921COMPAT_SYSCALL_DEFINE4(wait4,
1922 compat_pid_t, pid,
1923 compat_uint_t __user *, stat_addr,
1924 int, options,
1925 struct compat_rusage __user *, ru)
1926{
1927 struct rusage r;
1928 long err = kernel_wait4(upid: pid, stat_addr, options, ru: ru ? &r : NULL);
1929 if (err > 0) {
1930 if (ru && put_compat_rusage(&r, ru))
1931 return -EFAULT;
1932 }
1933 return err;
1934}
1935
1936COMPAT_SYSCALL_DEFINE5(waitid,
1937 int, which, compat_pid_t, pid,
1938 struct compat_siginfo __user *, infop, int, options,
1939 struct compat_rusage __user *, uru)
1940{
1941 struct rusage ru;
1942 struct waitid_info info = {.status = 0};
1943 long err = kernel_waitid(which, upid: pid, infop: &info, options, ru: uru ? &ru : NULL);
1944 int signo = 0;
1945 if (err > 0) {
1946 signo = SIGCHLD;
1947 err = 0;
1948 if (uru) {
1949 /* kernel_waitid() overwrites everything in ru */
1950 if (COMPAT_USE_64BIT_TIME)
1951 err = copy_to_user(to: uru, from: &ru, n: sizeof(ru));
1952 else
1953 err = put_compat_rusage(&ru, uru);
1954 if (err)
1955 return -EFAULT;
1956 }
1957 }
1958
1959 if (!infop)
1960 return err;
1961
1962 if (!user_write_access_begin(infop, sizeof(*infop)))
1963 return -EFAULT;
1964
1965 unsafe_put_user(signo, &infop->si_signo, Efault);
1966 unsafe_put_user(0, &infop->si_errno, Efault);
1967 unsafe_put_user(info.cause, &infop->si_code, Efault);
1968 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1969 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1970 unsafe_put_user(info.status, &infop->si_status, Efault);
1971 user_write_access_end();
1972 return err;
1973Efault:
1974 user_write_access_end();
1975 return -EFAULT;
1976}
1977#endif
1978
1979/*
1980 * This needs to be __function_aligned as GCC implicitly makes any
1981 * implementation of abort() cold and drops alignment specified by
1982 * -falign-functions=N.
1983 *
1984 * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345#c11
1985 */
1986__weak __function_aligned void abort(void)
1987{
1988 BUG();
1989
1990 /* if that doesn't kill us, halt */
1991 panic(fmt: "Oops failed to kill thread");
1992}
1993EXPORT_SYMBOL(abort);
1994