Commit 5f8aadd8 authored Mar 14, 2012 by Oleg Nesterov Committed by Linus Torvalds Mar 20, 2012

CLONE_PARENT shouldn't allow to set ->exit_signal



The child must not control its ->exit_signal, it is the parent who
decides which signal the child should use for notification.

This means that CLONE_PARENT should not use "clone_flags & CSIGNAL",
the forking task is the sibling of the new process and their parent
doesn't control exit_signal in this case.

This patch uses ->exit_signal of the forking process, but perhaps
we should simply use SIGCHLD.

We read group_leader->exit_signal lockless, this can race with the
ORIGINAL_SIGNAL -> SIGCHLD transition, but this is fine.

Potentially this change allows to kill self_exec_id/parent_exec_id.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ed378a52

kernel/fork.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -1340,7 +1340,13 @@ static struct task_struct *copy_process(unsigned long clone_flags,
		clear_all_latency_tracing(p);

		/* ok, now we should be set up.. */
		p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
		if (clone_flags & CLONE_THREAD)
		p->exit_signal = -1;
		else if (clone_flags & CLONE_PARENT)
		p->exit_signal = current->group_leader->exit_signal;
		else
		p->exit_signal = (clone_flags & CSIGNAL);

		p->pdeath_signal = 0;
		p->exit_state = 0;

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