Homeless Veterans Prevention Act of 2017 This bill provides that the services for which a recipient of a grant under the Department of Veterans Affairs (VA) comprehensive service program for homeless veterans may receive per diem payments may include furnishing care for a dependent under the care of a veteran who is receiving services. The VA shall enter into partnerships with public or private entities to fund a portion of the legal services such entities provide to homeless veterans and veterans at risk of homelessness related to housing, family law, income support, and criminal defense. The bill: (1) expands VA dental care authority authority to include those veterans receiving assistance under the United States Housing Act of 1937, (2) repeals the September 30, 2013, sunset on the authority of the VA and the Department of Labor to carry out a program of referral and counseling for veterans who are at risk of homelessness and are transitioning from certain institutions, including penal institutions, and (3) extends supportive services assistance for very low-income veteran families in permanent housing. The Government Accountability Office shall complete a study of VA assistance to homeless veterans. The requirement that the VA report annually on its assistance programs for homeless veterans is eliminated.