ecryptfs_write_header_metadata(char *virt,
			       struct ecryptfs_crypt_stat *crypt_stat,
			       size_t *written)
{
	u32 header_extent_size;
	u16 num_header_extents_at_front;

	header_extent_size = (u32)crypt_stat->extent_size;
	num_header_extents_at_front =
		(u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
	put_unaligned_be32(header_extent_size, virt);
	virt += 4;
	put_unaligned_be16(num_header_extents_at_front, virt);
	(*written) = 6;
}

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