linux-kernel - [PATCH 4.4 51/58] virtio_blk: fix panic in initialization error path

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Date:   Wed,  9 Aug 2017 12:42:03 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Omar Sandoval <osandov@...com>,
        Jeff Moyer <jmoyer@...hat.com>, Jens Axboe <axboe@...com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 4.4 51/58] virtio_blk: fix panic in initialization error path

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Omar Sandoval <osandov@...com>


[ Upstream commit 6bf6b0aa3da84a3d9126919a94c49c0fb7ee2fb3 ]

If blk_mq_init_queue() returns an error, it gets assigned to
vblk->disk->queue. Then, when we call put_disk(), we end up calling
blk_put_queue() with the ERR_PTR, causing a bad dereference. Fix it by
only assigning to vblk->disk->queue on success.

Signed-off-by: Omar Sandoval <osandov@...com>
Reviewed-by: Jeff Moyer <jmoyer@...hat.com>
Signed-off-by: Jens Axboe <axboe@...com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/block/virtio_blk.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -641,11 +641,12 @@ static int virtblk_probe(struct virtio_d
 	if (err)
 		goto out_put_disk;
 
-	q = vblk->disk->queue = blk_mq_init_queue(&vblk->tag_set);
+	q = blk_mq_init_queue(&vblk->tag_set);
 	if (IS_ERR(q)) {
 		err = -ENOMEM;
 		goto out_free_tags;
 	}
+	vblk->disk->queue = q;
 
 	q->queuedata = vblk;