This is a note to let you know that I've just added the patch titled
block: unhash blkdev part inode when the part is deleted
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
block-unhash-blkdev-part-inode-when-the-part-is-deleted.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From ming.lei@xxxxxxxxxx Thu Dec 15 07:48:48 2022
From: Ming Lei <ming.lei@xxxxxxxxxx>
Date: Tue, 13 Dec 2022 15:16:03 +0800
Subject: block: unhash blkdev part inode when the part is deleted
To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>, stable@xxxxxxxxxxxxxxx
Cc: Jens Axboe <axboe@xxxxxxxxx>, linux-block@xxxxxxxxxxxxxxx, Ming Lei <ming.lei@xxxxxxxxxx>, Shiwei Cui <cuishw@xxxxxxxxxx>, Christoph Hellwig <hch@xxxxxx>, Jan Kara <jack@xxxxxxx>
Message-ID: <20221213071603.1197703-1-ming.lei@xxxxxxxxxx>
From: Ming Lei <ming.lei@xxxxxxxxxx>
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:
1) 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
2) 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@xxxxxx/
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@xxxxxxxxxx>
Tested-by: Shiwei Cui <cuishw@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
block/partition-generic.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -272,6 +272,7 @@ void delete_partition(struct gendisk *di
struct disk_part_tbl *ptbl =
rcu_dereference_protected(disk->part_tbl, 1);
struct hd_struct *part;
+ struct block_device *bdev;
if (partno >= ptbl->len)
return;
@@ -292,6 +293,12 @@ void delete_partition(struct gendisk *di
* "in-use" until we really free the gendisk.
*/
blk_invalidate_devt(part_devt(part));
+
+ bdev = bdget(part_devt(part));
+ if (bdev) {
+ remove_inode_hash(bdev->bd_inode);
+ bdput(bdev);
+ }
hd_struct_kill(part);
}
Patches currently in stable-queue which might be from ming.lei@xxxxxxxxxx are
queue-5.4/block-unhash-blkdev-part-inode-when-the-part-is-deleted.patch
