From 8ce6cbc44f9ca78cac43506c84fcdd7beadee07f Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Mon, 22 Feb 2021 11:00:20 +0800 Subject: [PATCH] block: fix use-after-free in disk_part_iter_next 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: Reported-by: syzbot+825f0f9657d4e528046e@syzkaller.appspotmail.com Signed-off-by: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang Signed-off-by: Cheng Jian --- 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; } -- GitLab