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Commit e7b2c406 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Al Viro
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fput: task_work_add() can fail if the caller has passed exit_task_work()



fput() assumes that it can't be called after exit_task_work() but
this is not true, for example free_ipc_ns()->shm_destroy() can do
this. In this case fput() silently leaks the file.

Change it to fallback to delayed_fput_work if task_work_add() fails.
The patch looks complicated but it is not, it changes the code from

	if (PF_KTHREAD) {
		schedule_work(...);
		return;
	}
	task_work_add(...)

to
	if (!PF_KTHREAD) {
		if (!task_work_add(...))
			return;
		/* fallback */
	}
	schedule_work(...);

As for shm_destroy() in particular, we could make another fix but I
think this change makes sense anyway. There could be another similar
user, it is not safe to assume that task_work_add() can't fail.

Reported-by: default avatarAndrey Vagin <avagin@openvz.org>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 698b8223
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