From: Ming Lei ming.lei@redhat.com
stable inclusion from linux-4.19.168 commit 3d13ebbd06697e2fb180a61bbff1ff244a9513e4
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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; }