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 @@ -256,14 +256,17 @@ 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; }