Fixes for 5.15

Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/queue-5.15/dm-delay-fix-a-race-between-delay_presuspend-and-del.patch b/queue-5.15/dm-delay-fix-a-race-between-delay_presuspend-and-del.patch
new file mode 100644 (file)
index 0000000..49688ab
--- /dev/null
+++ b/queue-5.15/dm-delay-fix-a-race-between-delay_presuspend-and-del.patch
@@ -0,0 +1,98 @@
+From 4ab1082df75134ee436f194692d5243ae8fdc7ec Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Wed, 29 Nov 2023 13:38:43 -0500
+Subject: dm-delay: fix a race between delay_presuspend and delay_bio
+
+From: Mikulas Patocka <mpatocka@redhat.com>
+
+[ Upstream commit 6fc45b6ed921dc00dfb264dc08c7d67ee63d2656 ]
+
+In delay_presuspend, we set the atomic variable may_delay and then stop
+the timer and flush pending bios. The intention here is to prevent the
+delay target from re-arming the timer again.
+
+However, this test is racy. Suppose that one thread goes to delay_bio,
+sees that dc->may_delay is one and proceeds; now, another thread executes
+delay_presuspend, it sets dc->may_delay to zero, deletes the timer and
+flushes pending bios. Then, the first thread continues and adds the bio to
+delayed->list despite the fact that dc->may_delay is false.
+
+Fix this bug by changing may_delay's type from atomic_t to bool and
+only access it while holding the delayed_bios_lock mutex. Note that we
+don't have to grab the mutex in delay_resume because there are no bios
+in flight at this point.
+
+Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
+Cc: stable@vger.kernel.org
+Signed-off-by: Mike Snitzer <snitzer@kernel.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ drivers/md/dm-delay.c | 17 ++++++++++++-----
+ 1 file changed, 12 insertions(+), 5 deletions(-)
+
+diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
+index 59e51d285b0e5..238028056d0cc 100644
+--- a/drivers/md/dm-delay.c
++++ b/drivers/md/dm-delay.c
+@@ -30,7 +30,7 @@ struct delay_c {
+       struct workqueue_struct *kdelayd_wq;
+       struct work_struct flush_expired_bios;
+       struct list_head delayed_bios;
+-      atomic_t may_delay;
++      bool may_delay;
+ 
+       struct delay_class read;
+       struct delay_class write;
+@@ -191,7 +191,7 @@ static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+       INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
+       INIT_LIST_HEAD(&dc->delayed_bios);
+       mutex_init(&dc->timer_lock);
+-      atomic_set(&dc->may_delay, 1);
++      dc->may_delay = true;
+       dc->argc = argc;
+ 
+       ret = delay_class_ctr(ti, &dc->read, argv);
+@@ -245,7 +245,7 @@ static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
+       struct dm_delay_info *delayed;
+       unsigned long expires = 0;
+ 
+-      if (!c->delay || !atomic_read(&dc->may_delay))
++      if (!c->delay)
+               return DM_MAPIO_REMAPPED;
+ 
+       delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
+@@ -254,6 +254,10 @@ static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
+       delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay);
+ 
+       mutex_lock(&delayed_bios_lock);
++      if (unlikely(!dc->may_delay)) {
++              mutex_unlock(&delayed_bios_lock);
++              return DM_MAPIO_REMAPPED;
++      }
+       c->ops++;
+       list_add_tail(&delayed->list, &dc->delayed_bios);
+       mutex_unlock(&delayed_bios_lock);
+@@ -267,7 +271,10 @@ static void delay_presuspend(struct dm_target *ti)
+ {
+       struct delay_c *dc = ti->private;
+ 
+-      atomic_set(&dc->may_delay, 0);
++      mutex_lock(&delayed_bios_lock);
++      dc->may_delay = false;
++      mutex_unlock(&delayed_bios_lock);
++
+       del_timer_sync(&dc->delay_timer);
+       flush_bios(flush_delayed_bios(dc, 1));
+ }
+@@ -276,7 +283,7 @@ static void delay_resume(struct dm_target *ti)
+ {
+       struct delay_c *dc = ti->private;
+ 
+-      atomic_set(&dc->may_delay, 1);
++      dc->may_delay = true;
+ }
+ 
+ static int delay_map(struct dm_target *ti, struct bio *bio)
+-- 
+2.42.0
+

diff --git a/queue-5.15/series b/queue-5.15/series
index b9a6b5a3ad580660f5d589cae0d58391d6a209c0..888cb734c0dafd025cf02324adf1043bd3209205 100644 (file)
--- a/queue-5.15/series
+++ b/queue-5.15/series
@@ -40,3 +40,4 @@ ext4-using-nofail-preallocation-in-ext4_es_insert_ex.patch
 ext4-fix-slab-use-after-free-in-ext4_es_insert_exten.patch
 ext4-make-sure-allocate-pending-entry-not-fail.patch
 tracing-kprobes-return-eaddrnotavail-when-func-matches-several-symbols.patch
+dm-delay-fix-a-race-between-delay_presuspend-and-del.patch