linux-kernel - [PATCH][next] null_blk: Fix null pointer dereference on nullb->disk on blk_cleanup

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Message-Id: <20210602100659.11058-1-colin.king@canonical.com>
Date:   Wed,  2 Jun 2021 11:06:59 +0100
From:   Colin King <colin.king@...onical.com>
To:     Jens Axboe <axboe@...nel.dk>,
        Damien Le Moal <damien.lemoal@....com>,
        Christoph Hellwig <hch@....de>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-block@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] null_blk: Fix null pointer dereference on nullb->disk on blk_cleanup_disk call

From: Colin Ian King <colin.king@...onical.com>

The error handling on a nullb->disk allocation currently jumps to
out_cleanup_disk that calls blk_cleanup_disk with a null pointer causing
a null pointer dereference issue. Fix this by jumping to out_cleanup_tags
instead.

Addresses-Coverity: ("Dereference after null check")
Fixes: 132226b301b5 ("null_blk: convert to blk_alloc_disk/blk_cleanup_disk")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/block/null_blk/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index d8e098f1e5b5..83d803cb57c8 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -1856,7 +1856,7 @@ static int null_add_dev(struct nullb_device *dev)
 			goto out_cleanup_tags;
 		nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
 		if (!nullb->disk)
-			goto out_cleanup_disk;
+			goto out_cleanup_tags;
 		nullb->disk->queue = nullb->q;
 	} else if (dev->queue_mode == NULL_Q_BIO) {
 		rv = -ENOMEM;
-- 
2.31.1