On Tue, Dec 13, 2022 at 03:16:55PM +0800, Ming Lei wrote:
v5.11 changes the blkdev lookup mechanism completely since commit 22ae8ce8b892 ("block: simplify bdev/disk lookup in blkdev_get"), and small part of the change is to unhash part bdev inode when deleting partition. Turns out this kind of change does fix one nasty issue in case of BLOCK_EXT_MAJOR:
- when one partition is deleted & closed, disk_put_part() is always
called before bdput(bdev), see blkdev_put(); so the part's devt can be freed & re-used before the inode is dropped
- then new partition with same devt can be created just before the
inode in 1) is dropped, then the old inode/bdev structurein 1) is re-used for this new partition, this way causes use-after-free and kernel panic.
It isn't possible to backport the whole big patchset of "merge struct block_device and struct hd_struct v4" for addressing this issue.
https://lore.kernel.org/linux-block/20201128161510.347752-1-hch@lst.de/
So fixes it by unhashing part bdev in delete_partition(), and this way is actually aligned with v5.11+'s behavior.
Backported from the following 5.10.y commit:
5f2f77560591 ("block: unhash blkdev part inode when the part is deleted")
Reported-by: Shiwei Cui cuishw@inspur.com Tested-by: Shiwei Cui cuishw@inspur.com Cc: Christoph Hellwig hch@lst.de Cc: Jan Kara jack@suse.cz Signed-off-by: Ming Lei ming.lei@redhat.com
block/partition-generic.c | 6 ++++++ 1 file changed, 6 insertions(+)
All now queued up, thanks!
greg k-h