Found by Coverity.
Reviewed-by: NMatt Caswell <matt@openssl.org>
Reviewed-by: NTim Hudson <tjh@openssl.org>
Reviewed-by: NPaul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8274)

(cherry picked from commit 23dc8feba817560485da00d690d7b7b9e5b15682)