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block: don't create too many partitions 

Commit a33df75c63 ("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 <bvanassche@acm.org>
Reported-by: syzbot+8fede7e30c7cee0de139@syzkaller.appspotmail.com
Fixes: a33df75c63 ("block: use an xarray for disk->part_tbl")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
rM2-mainline
Ming Lei 2021-03-27 15:13:09 +08:00 committed by Jens Axboe
parent 7de55b7d6f
commit e82fc78557
1 changed files with 7 additions and 0 deletions
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7
block/partitions/core.c
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@ -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.