static struct block_device *ext4_blkdev_get(dev_t dev, struct super_block *sb)
{
	struct block_device *bdev;
	char b[BDEVNAME_SIZE];

	bdev = blkdev_get_by_dev(dev, FMODE_READ|FMODE_WRITE|FMODE_EXCL, sb);
	if (IS_ERR(bdev))
		goto fail;
	return bdev;

fail:
	ext4_msg(sb, KERN_ERR, "failed to open journal device %s: %ld",
			__bdevname(dev, b), PTR_ERR(bdev));
	return NULL;
}

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.