From 0d0bd28c500173bfca78aa840f8f36d261ef1765 Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Tue, 8 Aug 2023 18:49:12 +0800 Subject: md/raid5-cache: fix null-ptr-deref for r5l_flush_stripe_to_raid() 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 Closes: https://lore.kernel.org/all/cddd7213-3dfd-4ab7-a3ac-edd54d74a626@fatooh.org/ Signed-off-by: Yu Kuai Reviewed-by: Christoph Hellwig Signed-off-by: Song Liu --- drivers/md/raid5-cache.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c index a29b9650260a..518b7cfa78b9 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); } /* -- cgit v1.2.3