block: don't create too many partitions

Commit a33df75 ("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 <[email protected]> Reported-by: [email protected] Fixes: a33df75 ("block: use an xarray for disk->part_tbl") Signed-off-by: Ming Lei <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
mrcsosa · Mar 27, 2021 · e82fc78 · e82fc78
1 parent 7de55b7
commit e82fc78
Showing 1 changed file with 7 additions and 0 deletions.
diff --git 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.