| From aebf5db917055b38f4945ed6d621d9f07a44ff30 Mon Sep 17 00:00:00 2001 |
| From: Ming Lei <ming.lei@redhat.com> |
| Date: Mon, 21 Dec 2020 12:33:35 +0800 |
| Subject: block: fix use-after-free in disk_part_iter_next |
| |
| From: Ming Lei <ming.lei@redhat.com> |
| |
| commit aebf5db917055b38f4945ed6d621d9f07a44ff30 upstream. |
| |
| Make sure that bdgrab() is done on the 'block_device' instance before |
| referring to it for avoiding use-after-free. |
| |
| Cc: <stable@vger.kernel.org> |
| Reported-by: syzbot+825f0f9657d4e528046e@syzkaller.appspotmail.com |
| Signed-off-by: Ming Lei <ming.lei@redhat.com> |
| Reviewed-by: Christoph Hellwig <hch@lst.de> |
| Signed-off-by: Jens Axboe <axboe@kernel.dk> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| block/genhd.c | 9 ++++++--- |
| 1 file changed, 6 insertions(+), 3 deletions(-) |
| |
| --- a/block/genhd.c |
| +++ b/block/genhd.c |
| @@ -159,14 +159,17 @@ struct hd_struct *disk_part_iter_next(st |
| part = rcu_dereference(ptbl->part[piter->idx]); |
| if (!part) |
| continue; |
| + get_device(part_to_dev(part)); |
| + piter->part = part; |
| if (!part_nr_sects_read(part) && |
| !(piter->flags & DISK_PITER_INCL_EMPTY) && |
| !(piter->flags & DISK_PITER_INCL_EMPTY_PART0 && |
| - piter->idx == 0)) |
| + piter->idx == 0)) { |
| + put_device(part_to_dev(part)); |
| + piter->part = NULL; |
| continue; |
| + } |
| |
| - get_device(part_to_dev(part)); |
| - piter->part = part; |
| piter->idx += inc; |
| break; |
| } |