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Commit b177d2d9 authored by Eddy Wu's avatar Eddy Wu Committed by Greg Kroah-Hartman
Browse files

fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent 



commit b4e00444cab4c3f3fec876dc0cccc8cbb0d1a948 upstream.

current->group_leader->exit_signal may change during copy_process() if
current->real_parent exits.

Move the assignment inside tasklist_lock to avoid the race.

Signed-off-by: default avatarEddy Wu <eddy_wu@trendmicro.com>
Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6612b754

kernel/fork.c

+5 −5
Original line number Diff line number Diff line
@@ -1965,14 +1965,9 @@ static __latent_entropy struct task_struct *copy_process( 
	/* ok, now we should be set up.. */

	p->pid = pid_nr(pid);

	if (clone_flags & CLONE_THREAD) {

		p->exit_signal = -1;

		p->group_leader = current->group_leader;

		p->tgid = current->tgid;

	} else {

		if (clone_flags & CLONE_PARENT)

			p->exit_signal = current->group_leader->exit_signal;

		else

			p->exit_signal = (clone_flags & CSIGNAL);

		p->group_leader = p;

		p->tgid = p->pid;

	}
@@ -2017,9 +2012,14 @@ static __latent_entropy struct task_struct *copy_process( 
	if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {

		p->real_parent = current->real_parent;

		p->parent_exec_id = current->parent_exec_id;

		if (clone_flags & CLONE_THREAD)

			p->exit_signal = -1;

		else

			p->exit_signal = current->group_leader->exit_signal;

	} else {

		p->real_parent = current;

		p->parent_exec_id = current->self_exec_id;

		p->exit_signal = (clone_flags & CSIGNAL);

	}



	klp_copy_process(p);