From e82fc7855749aa197740a60ef22c492c41ea5d5f Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Sat, 27 Mar 2021 15:13:09 +0800 Subject: [PATCH] block: don't create too many partitions Commit a33df75c6328 ("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: Bart Van Assche Reported-by: syzbot+8fede7e30c7cee0de139@syzkaller.appspotmail.com Fixes: a33df75c6328 ("block: use an xarray for disk->part_tbl") Signed-off-by: Ming Lei Signed-off-by: Jens Axboe --- block/partitions/core.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/block/partitions/core.c b/block/partitions/core.c index 1a7558917c47..46f055bc7ecb 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -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.