6.4-stable review patch. If anyone has any objections, please let me know.
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From: Yu Kuai yukuai3@huawei.com
[ 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@fatooh.org Closes: https://lore.kernel.org/all/cddd7213-3dfd-4ab7-a3ac-edd54d74a626@fatooh.org/ Signed-off-by: Yu Kuai yukuai3@huawei.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Song Liu song@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 5c246b2697e0b..21653e1ed9384 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); }
/*