Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a98fdcef authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

fix the "remove task_ppid_nr_ns" commit 



Commit 84427eae (remove task_ppid_nr_ns)
moved the task_tgid_nr_ns(task->real_parent) outside of lock_task_sighand().
This is wrong, ->real_parent could be freed/reused.

Both ->parent/real_parent point to nothing after __exit_signal() because
we remove the child from ->children list, and thus the child can't be
reparented when its parent exits.

rcu_read_lock() protects ->parent/real_parent, but _only_ if we know it was
valid before we take rcu lock.

Revert this part of the patch.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4fd3670e

fs/proc/array.c

+1 −1
Original line number Original line Diff line number Diff line
@@ -426,7 +426,6 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole) 
	cgtime = gtime = cputime_zero;

	cgtime = gtime = cputime_zero;





	rcu_read_lock();

	rcu_read_lock();

	ppid = task_tgid_nr_ns(task->real_parent, ns);

	if (lock_task_sighand(task, &flags)) {

	if (lock_task_sighand(task, &flags)) {

		struct signal_struct *sig = task->signal;

		struct signal_struct *sig = task->signal;
@@ -465,6 +464,7 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole) 
		}

		}





		sid = task_session_nr_ns(task, ns);

		sid = task_session_nr_ns(task, ns);

		ppid = task_tgid_nr_ns(task->real_parent, ns);

		pgid = task_pgrp_nr_ns(task, ns);

		pgid = task_pgrp_nr_ns(task, ns);





		unlock_task_sighand(task, &flags);

		unlock_task_sighand(task, &flags);