Commit e82fc785 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: don't create too many partitions 



Commit a33df75c ("block: use an xarray for disk->part_tbl") drops the
check on max supported number of partitionsr, and allows partition with
bigger partition numbers to be added. However, ->bd_partno is defined as
u8, so partition index of xarray table may not match with ->bd_partno.
Then delete_partition() may delete one unmatched partition, and caused
use-after-free.

Reviewed-by: default avatarBart Van Assche <bvanassche@acm.org>
Reported-by: default avatar <syzbot+8fede7e30c7cee0de139@syzkaller.appspotmail.com>
Fixes: a33df75c ("block: use an xarray for disk->part_tbl")
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7de55b7d

block/partitions/core.c

+7 −0
Original line number Diff line number Diff line
@@ -322,6 +322,13 @@ static struct block_device *add_partition(struct gendisk *disk, int partno, 
	const char *dname;

	int err;



	/*

	 * disk_max_parts() won't be zero, either GENHD_FL_EXT_DEVT is set

	 * or 'minors' is passed to alloc_disk().

	 */

	if (partno >= disk_max_parts(disk))

		return ERR_PTR(-EINVAL);



	/*

	 * Partitions are not supported on zoned block devices that are used as

	 * such.