Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751832AbdGYVet (ORCPT ); Tue, 25 Jul 2017 17:34:49 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60666 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751645AbdGYTRQ (ORCPT ); Tue, 25 Jul 2017 15:17:16 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mikulas Patocka , NeilBrown , Shaohua Li Subject: [PATCH 3.18 30/60] md: dont use flush_signals in userspace processes Date: Tue, 25 Jul 2017 12:16:21 -0700 Message-Id: <20170725191618.331128706@linuxfoundation.org> X-Mailer: git-send-email 2.13.3 In-Reply-To: <20170725191614.043749784@linuxfoundation.org> References: <20170725191614.043749784@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2316 Lines: 70 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka 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: Mikulas Patocka Acked-by: NeilBrown Signed-off-by: Shaohua Li Signed-off-by: Greg Kroah-Hartman --- drivers/md/raid1.c | 5 ++++- drivers/md/raid5.c | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1120,13 +1120,16 @@ static void make_request(struct mddev *m */ DEFINE_WAIT(w); for (;;) { - flush_signals(current); + sigset_t full, old; prepare_to_wait(&conf->wait_barrier, &w, TASK_INTERRUPTIBLE); if (bio_end_sector(bio) <= mddev->suspend_lo || bio->bi_iter.bi_sector >= mddev->suspend_hi) break; + sigfillset(&full); + sigprocmask(SIG_BLOCK, &full, &old); schedule(); + sigprocmask(SIG_SETMASK, &old, NULL); } finish_wait(&conf->wait_barrier, &w); } --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4705,12 +4705,15 @@ static void make_request(struct mddev *m * userspace, we want an interruptible * wait. */ - flush_signals(current); prepare_to_wait(&conf->wait_for_overlap, &w, TASK_INTERRUPTIBLE); if (logical_sector >= mddev->suspend_lo && logical_sector < mddev->suspend_hi) { + sigset_t full, old; + sigfillset(&full); + sigprocmask(SIG_BLOCK, &full, &old); schedule(); + sigprocmask(SIG_SETMASK, &old, NULL); do_prepare = true; } goto retry;