[PATCH v2] md/raid5-ppl: fix use-after-free in ppl_do_flush()

The loop in ppl_do_flush() continues iterating after calling
ppl_io_unit_finished(), touching io->pending_flushes and leading to a
use-after-free.

Add a break statement to stop the loop once io is freed.

Fixes: 1532d9e87e8b ("raid5-ppl: PPL support for disks with write-back cache enabled")
Reported-by: Dan Carpenter <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Sajal Gupta <[email protected]>
---
Compile tested only.

Changes in v2:
 - drop the refcount_t conversion

v1: https://lore.kernel.org/all/[email protected]/

 drivers/md/raid5-ppl.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c
index a70cbec12ed0..c3cfdd66d8b0 100644
--- a/drivers/md/raid5-ppl.c
+++ b/drivers/md/raid5-ppl.c
@@ -643,8 +643,10 @@ static void ppl_do_flush(struct ppl_io_unit *io)
 	log->disk_flush_bitmap = 0;

 	for (i = flushed_disks ; i < raid_disks; i++) {
-		if (atomic_dec_and_test(&io->pending_flushes))
+		if (atomic_dec_and_test(&io->pending_flushes)) {
 			ppl_io_unit_finished(io);
+			break;
+		}
 	}
 }

--
2.54.0