struct buffer_head *isofs_bread(struct inode *inode, sector_t block)
{
	sector_t blknr = isofs_bmap(inode, block);
	if (!blknr)
		return NULL;
	return sb_bread(inode->i_sb, blknr);
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.