EVP_MD_CTX_copy_ex was implemented with a memcpy, which doesn't work well when some of the pointers need to be copied, and ssl_verify_cert_chain didn't account for set_ex_data failing. Change-Id: Ieb556aeda6ab2e4c810f27012fefb1e65f860023 Reviewed-on: https://boringssl-review.googlesource.com/5911 Reviewed-by: Adam Langley <agl@google.com>