On 02/15, Al Viro wrote: > > On Sat, Feb 15, 2014 at 03:27:00PM +0100, Oleg Nesterov wrote: > > > 1. info->q can be already freed if SIGQUEUE_PREALLOC. > > > > Once get_signal_to_deliver() or any other caller drops ->siglock > > another thread can do sys_timer_delete()->sigqueue_free(). > > How the devil would it find the sucker? It simply frees the SIGQUEUE_PREALLOC sigqueue, k_itimer->sigq. > It's off the list already. Exactly, list_empty(q->list) == T. So release_posix_timer()->sigqueue_free() assumes we can safely free it. > > 2. We need to move do_schedule_next_timer() from dequeue_signal() > > here. > > > > Otherwise ->q can be reused/overwritten by the next send_sigqueue() > > right affter ->siglock is dropped. > > Ditto. We rip them out of queue on collect_signal(); Yes, and dequeue_signal()->do_schedule_next_timer() can trigger another send_sigqueue() which uses the same SIGQUEUE_PREALLOC sigqueue once we drop ->siglock. This is not that bad, but at least ->si_overrun can be overwritten before __setup_rt_frame()->copy_siginfo_to_user(). Oleg. _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
