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Commit 94e0ff07 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Greg Kroah-Hartman
Browse files

md: don't use flush_signals in userspace processes 



commit f9c79bc05a2a91f4fba8bfd653579e066714b1ec upstream.

The function flush_signals clears all pending signals for the process. It
may be used by kernel threads when we need to prepare a kernel thread for
responding to signals. However using this function for an userspaces
processes is incorrect - clearing signals without the program expecting it
can cause misbehavior.

The raid1 and raid5 code uses flush_signals in its request routine because
it wants to prepare for an interruptible wait. This patch drops
flush_signals and uses sigprocmask instead to block all signals (including
SIGKILL) around the schedule() call. The signals are not lost, but the
schedule() call won't respond to them.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Acked-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 936c77c8

drivers/md/raid1.c

+4 −1
Original line number Original line Diff line number Diff line
@@ -1120,13 +1120,16 @@ static void make_request(struct mddev *mddev, struct bio * bio) 
		 */

		 */

		DEFINE_WAIT(w);

		DEFINE_WAIT(w);

		for (;;) {

		for (;;) {

			flush_signals(current);

			sigset_t full, old;

			prepare_to_wait(&conf->wait_barrier,

			prepare_to_wait(&conf->wait_barrier,

					&w, TASK_INTERRUPTIBLE);

					&w, TASK_INTERRUPTIBLE);

			if (bio_end_sector(bio) <= mddev->suspend_lo ||

			if (bio_end_sector(bio) <= mddev->suspend_lo ||

			    bio->bi_iter.bi_sector >= mddev->suspend_hi)

			    bio->bi_iter.bi_sector >= mddev->suspend_hi)

				break;

				break;

			sigfillset(&full);

			sigprocmask(SIG_BLOCK, &full, &old);

			schedule();

			schedule();

			sigprocmask(SIG_SETMASK, &old, NULL);

		}

		}

		finish_wait(&conf->wait_barrier, &w);

		finish_wait(&conf->wait_barrier, &w);

	}

	}

drivers/md/raid5.c

+4 −1
Original line number Original line Diff line number Diff line
@@ -4705,12 +4705,15 @@ static void make_request(struct mddev *mddev, struct bio * bi) 
				 * userspace, we want an interruptible

				 * userspace, we want an interruptible

				 * wait.

				 * wait.

				 */

				 */

				flush_signals(current);

				prepare_to_wait(&conf->wait_for_overlap,

				prepare_to_wait(&conf->wait_for_overlap,

						&w, TASK_INTERRUPTIBLE);

						&w, TASK_INTERRUPTIBLE);

				if (logical_sector >= mddev->suspend_lo &&

				if (logical_sector >= mddev->suspend_lo &&

				    logical_sector < mddev->suspend_hi) {

				    logical_sector < mddev->suspend_hi) {

					sigset_t full, old;

					sigfillset(&full);

					sigprocmask(SIG_BLOCK, &full, &old);

					schedule();

					schedule();

					sigprocmask(SIG_SETMASK, &old, NULL);

					do_prepare = true;

					do_prepare = true;

				}

				}

				goto retry;

				goto retry;