Commit 1799763d authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Sasha Levin

md: don't use flush_signals in userspace processes

[ Upstream commit f9c79bc0 ]

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>
Cc: stable@vger.kernel.org
Acked-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent c510d666
...@@ -1118,7 +1118,7 @@ static void make_request(struct mddev *mddev, struct bio * bio) ...@@ -1118,7 +1118,7 @@ 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 ||
...@@ -1127,7 +1127,10 @@ static void make_request(struct mddev *mddev, struct bio * bio) ...@@ -1127,7 +1127,10 @@ static void make_request(struct mddev *mddev, struct bio * bio)
!md_cluster_ops->area_resyncing(mddev, !md_cluster_ops->area_resyncing(mddev,
bio->bi_iter.bi_sector, bio_end_sector(bio)))) bio->bi_iter.bi_sector, bio_end_sector(bio))))
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);
} }
......
...@@ -5275,12 +5275,15 @@ static void make_request(struct mddev *mddev, struct bio * bi) ...@@ -5275,12 +5275,15 @@ 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;
......
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