Commit 234c53e5 authored Nov 14, 2022 by Yang Yingliang Committed by Greg Kroah-Hartman Mar 11, 2023

ubi: Fix possible null-ptr-deref in ubi_free_volume()



[ Upstream commit c15859bfd326c10230f09cb48a17f8a35f190342 ]

It willl cause null-ptr-deref in the following case:

uif_init()
  ubi_add_volume()
    cdev_add() -> if it fails, call kill_volumes()
    device_register()

kill_volumes() -> if ubi_add_volume() fails call this function
  ubi_free_volume()
    cdev_del()
    device_unregister() -> trying to delete a not added device,
			   it causes null-ptr-deref

So in ubi_free_volume(), it delete devices whether they are added
or not, it will causes null-ptr-deref.

Handle the error case whlie calling ubi_add_volume() to fix this
problem. If add volume fails, set the corresponding vol to null,
so it can not be accessed in kill_volumes() and release the
resource in ubi_add_volume() error path.

Fixes: 801c135c ("UBI: Unsorted Block Images")
Suggested-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 1f206002

drivers/mtd/ubi/build.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -467,6 +467,7 @@ static int uif_init(struct ubi_device *ubi)
		err = ubi_add_volume(ubi, ubi->volumes[i]);
		if (err) {
		ubi_err(ubi, "cannot add volume %d", i);
		ubi->volumes[i] = NULL;
		goto out_volumes;
		}
		}

drivers/mtd/ubi/vmt.c

+6 −6

Original line number	Diff line number	Diff line
		@@ -582,6 +582,7 @@ int ubi_add_volume(struct ubi_device ubi, struct ubi_volume vol)
		if (err) {
		ubi_err(ubi, "cannot add character device for volume %d, error %d",
		vol_id, err);
		vol_release(&vol->dev);
		return err;
		}

		@@ -592,14 +593,13 @@ int ubi_add_volume(struct ubi_device ubi, struct ubi_volume vol)
		vol->dev.groups = volume_dev_groups;
		dev_set_name(&vol->dev, "%s_%d", ubi->ubi_name, vol->vol_id);
		err = device_register(&vol->dev);
		if (err)
		goto out_cdev;

		self_check_volumes(ubi);
		if (err) {
		cdev_del(&vol->cdev);
		put_device(&vol->dev);
		return err;
		}

		out_cdev:
		cdev_del(&vol->cdev);
		self_check_volumes(ubi);
		return err;
		}