From: Ming Lei <ming.lei@redhat.com> stable inclusion from linux-4.19.168 commit 3d13ebbd06697e2fb180a61bbff1ff244a9513e4 -------------------------------- 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> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com> --- block/genhd.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 862a2f3c536f..d8a9c901eaef 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -208,14 +208,17 @@ struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter) 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; } -- 2.25.1