6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Yu Kuai <yukuai3@xxxxxxxxxx>
[ Upstream commit 0d0bd28c500173bfca78aa840f8f36d261ef1765 ]
r5l_flush_stripe_to_raid() will check if the list 'flushing_ios' is
empty, and then submit 'flush_bio', however, r5l_log_flush_endio()
is clearing the list first and then clear the bio, which will cause
null-ptr-deref:
T1: submit flush io
raid5d
handle_active_stripes
r5l_flush_stripe_to_raid
// list is empty
// add 'io_end_ios' to the list
bio_init
submit_bio
// io1
T2: io1 is done
r5l_log_flush_endio
list_splice_tail_init
// clear the list
T3: submit new flush io
...
r5l_flush_stripe_to_raid
// list is empty
// add 'io_end_ios' to the list
bio_init
bio_uninit
// clear bio->bi_blkg
submit_bio
// null-ptr-deref
Fix this problem by clearing bio before clearing the list in
r5l_log_flush_endio().
Fixes: 0dd00cba99c3 ("raid5-cache: fully initialize flush_bio when needed")
Reported-and-tested-by: Corey Hickey <bugfood-ml@xxxxxxxxxx>
Closes: https://lore.kernel.org/all/cddd7213-3dfd-4ab7-a3ac-edd54d74a626@xxxxxxxxxx/
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/md/raid5-cache.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 2eac4a50d99bd..8b3fc484fd758 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1260,14 +1260,13 @@ static void r5l_log_flush_endio(struct bio *bio)
if (bio->bi_status)
md_error(log->rdev->mddev, log->rdev);
+ bio_uninit(bio);
spin_lock_irqsave(&log->io_list_lock, flags);
list_for_each_entry(io, &log->flushing_ios, log_sibling)
r5l_io_run_stripes(io);
list_splice_tail_init(&log->flushing_ios, &log->finished_ios);
spin_unlock_irqrestore(&log->io_list_lock, flags);
-
- bio_uninit(bio);
}
/*
--
2.40.1
