Commit b1442b05 authored Apr 02, 2009 by Oleg Nesterov Committed by Linus Torvalds Apr 02, 2009

reparent_thread: fix the "is it traced" check



reparent_thread() uses ptrace_reparented() to check whether this thread is
ptraced, in that case we should not notify the new parent.

But ptrace_reparented() is not exactly correct when the reparented thread
is traced by /sbin/init, because forget_original_parent() has already
changed ->real_parent.

Currently, the only problem is the false notification.  But with the next
patch the kernel crash in this (yes, pathological) case.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 0a967a04

kernel/exit.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -832,7 +832,7 @@ static void reparent_thread(struct task_struct p, struct task_struct father)
	/* If we'd notified the old parent about this child's death,		/* If we'd notified the old parent about this child's death,
	* also notify the new parent.		* also notify the new parent.
	*/		*/
	if (!ptrace_reparented(p) &&		if (!p->ptrace &&
	p->exit_state == EXIT_ZOMBIE && thread_group_empty(p))		p->exit_state == EXIT_ZOMBIE && thread_group_empty(p))
	do_notify_parent(p, p->exit_signal);		do_notify_parent(p, p->exit_signal);

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