Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752969AbdGYUda (ORCPT ); Tue, 25 Jul 2017 16:33:30 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34252 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752854AbdGYTVb (ORCPT ); Tue, 25 Jul 2017 15:21:31 -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 4.9 057/125] md: dont use flush_signals in userspace processes Date: Tue, 25 Jul 2017 12:19:32 -0700 Message-Id: <20170725192017.468313683@linuxfoundation.org> X-Mailer: git-send-email 2.13.3 In-Reply-To: <20170725192014.314851996@linuxfoundation.org> References: <20170725192014.314851996@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: 2436 Lines: 72 4.9-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 @@ -1073,7 +1073,7 @@ static void raid1_make_request(struct md */ 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 || @@ -1082,7 +1082,10 @@ static void raid1_make_request(struct md !md_cluster_ops->area_resyncing(mddev, WRITE, bio->bi_iter.bi_sector, bio_end_sector(bio)))) 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 @@ -5300,12 +5300,15 @@ static void raid5_make_request(struct md * 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;