| Message ID | 20221205122502.841896-1-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [5.10.y,stable] block: unhash blkdev part inode when the part is deleted | expand |
On Mon, Dec 05, 2022 at 08:25:02PM +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: > > 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 fbig patchset of "merge struct "fbig"? > 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. > > Reported-by: cuishw@inspur.com > Tested-by: cuishw@inspur.com We need a real name and this in a proper format as well (<>) > Cc: Christoph Hellwig <hch@lst.de> > Cc: Jan Kara <jack@suse.cz> > Signed-off-by: Ming Lei <ming.lei@redhat.com> What about for kernels older than 5.10? thanks, greg k-h
On Mon, Dec 05, 2022 at 01:33:32PM +0100, Greg Kroah-Hartman wrote: > On Mon, Dec 05, 2022 at 08:25:02PM +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: > > > > 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 fbig patchset of "merge struct > > "fbig"? OK, will fix it in v2. > > > 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. > > > > Reported-by: cuishw@inspur.com > > Tested-by: cuishw@inspur.com > > We need a real name and this in a proper format as well (<>) cuishw, care to share us your name? :-) > > > Cc: Christoph Hellwig <hch@lst.de> > > Cc: Jan Kara <jack@suse.cz> > > Signed-off-by: Ming Lei <ming.lei@redhat.com> > > What about for kernels older than 5.10? All -stable kernels older should need this kind of fix. If this patch is acked, I can backport to other -stable kernels. Thanks, Ming
diff --git a/block/partitions/core.c b/block/partitions/core.c index a02e22411594..e3d61ec4a5a6 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -329,6 +329,7 @@ void delete_partition(struct hd_struct *part) struct gendisk *disk = part_to_disk(part); struct disk_part_tbl *ptbl = rcu_dereference_protected(disk->part_tbl, 1); + struct block_device *bdev; /* * ->part_tbl is referenced in this part's release handler, so @@ -346,6 +347,12 @@ void delete_partition(struct hd_struct *part) * "in-use" until we really free the gendisk. */ blk_invalidate_devt(part_devt(part)); + + bdev = bdget_part(part); + if (bdev) { + remove_inode_hash(bdev->bd_inode); + bdput(bdev); + } percpu_ref_kill(&part->ref); }
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 fbig 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. Reported-by: cuishw@inspur.com Tested-by: 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/partitions/core.c | 7 +++++++ 1 file changed, 7 insertions(+)