From: Mikulas Patocka Date: Wed, 7 Jun 2017 23:05:31 +0000 (-0400) Subject: md: don't use flush_signals in userspace processes X-Git-Tag: v3.18.63~31 X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=94e0ff076aacf541ef392a2b0aa493ed71f48614;p=linux 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: Mikulas Patocka Acked-by: NeilBrown Signed-off-by: Shaohua Li Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index b194ccfd3a36..63e57254ff62 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1120,13 +1120,16 @@ static void make_request(struct mddev *mddev, struct bio * bio) */ 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); } diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 48096d09fef3..a7170a31837e 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4705,12 +4705,15 @@ static void make_request(struct mddev *mddev, struct bio * bi) * 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;