From: Ming Lei <[email protected]> commit aebf5db917055b38f4945ed6d621d9f07a44ff30 upstream.
Make sure that bdgrab() is done on the 'block_device' instance before referring to it for avoiding use-after-free. Cc: <[email protected]> Reported-by: [email protected] Signed-off-by: Ming Lei <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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; }
