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[stable-4.19,Resend,1/7] block: fix NULL pointer dereference in register_disk

Message ID 20210208150426.62755-2-jinpu.wang@cloud.ionos.com
State New
Headers show
Series block layer bugfix | expand

Commit Message

Jinpu Wang Feb. 8, 2021, 3:04 p.m. UTC 
From: zhengbin <zhengbin13@huawei.com>

If __device_add_disk-->bdi_register_owner-->bdi_register-->
bdi_register_va-->device_create_vargs fails, bdi->dev is still
NULL, __device_add_disk-->register_disk will visit bdi->dev->kobj.
This patch fixes that.

Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 4d7c1d3fd7c7eda7dea351f071945e843a46c145)
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
---
 block/genhd.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/block/genhd.c b/block/genhd.c
index 2b536ab570ac..6965dde96373 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -652,10 +652,12 @@  static void register_disk(struct device *parent, struct gendisk *disk)
 		kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
 	disk_part_iter_exit(&piter);
 
-	err = sysfs_create_link(&ddev->kobj,
-				&disk->queue->backing_dev_info->dev->kobj,
-				"bdi");
-	WARN_ON(err);
+	if (disk->queue->backing_dev_info->dev) {
+		err = sysfs_create_link(&ddev->kobj,
+			  &disk->queue->backing_dev_info->dev->kobj,
+			  "bdi");
+		WARN_ON(err);
+	}
 }
 
 /**