From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:54896 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754337AbdGYAI3 (ORCPT ); Mon, 24 Jul 2017 20:08:29 -0400 Subject: Patch "md: don't use flush_signals in userspace processes" has been added to the 4.4-stable tree To: mpatocka@redhat.com, gregkh@linuxfoundation.org, neilb@suse.com, shli@fb.com Cc: , From: Date: Mon, 24 Jul 2017 17:08:23 -0700 Message-ID: <1500941303134165@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled md: don't use flush_signals in userspace processes to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: md-don-t-use-flush_signals-in-userspace-processes.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From f9c79bc05a2a91f4fba8bfd653579e066714b1ec Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 7 Jun 2017 19:05:31 -0400 Subject: md: don't use flush_signals in userspace processes 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 @@ -1088,7 +1088,7 @@ 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 || @@ -1097,7 +1097,10 @@ static void make_request(struct mddev *m !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 @@ -5279,12 +5279,15 @@ 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; Patches currently in stable-queue which might be from mpatocka@redhat.com are queue-4.4/md-don-t-use-flush_signals-in-userspace-processes.patch