Update Golang 1.12.12 (CVE-2019-17596)

Golang 1.12.12
-------------------------------

go1.12.12 (released 2019/10/17) includes fixes to the go command, runtime,
syscall and net packages. See the Go 1.12.12 milestone on our issue tracker for
details.

https://github.com/golang/go/issues?q=milestone%3AGo1.12.12

Golang 1.12.11 (CVE-2019-17596)
-------------------------------

go1.12.11 (released 2019/10/17) includes security fixes to the crypto/dsa
package. See the Go 1.12.11 milestone on our issue tracker for details.
https://github.com/golang/go/issues?q=milestone%3AGo1.12.11

[security] Go 1.13.2 and Go 1.12.11 are released

Hi gophers,

We have just released Go 1.13.2 and Go 1.12.11 to address a recently reported
security issue. We recommend that all affected users update to one of these
releases (if you're not sure which, choose Go 1.13.2).

Invalid DSA public keys can cause a panic in dsa.Verify. In particular, using
crypto/x509.Verify on a crafted X.509 certificate chain can lead to a panic,
even if the certificates don't chain to a trusted root. The chain can be
delivered via a crypto/tls connection to a client, or to a server that accepts
and verifies client certificates. net/http clients can be made to crash by an
HTTPS server, while net/http servers that accept client certificates will
recover the panic and are unaffected.

Moreover, an application might crash invoking
crypto/x509.(*CertificateRequest).CheckSignature on an X.509 certificate
request, parsing a golang.org/x/crypto/openpgp Entity, or during a
golang.org/x/crypto/otr conversation. Finally, a golang.org/x/crypto/ssh client
can panic due to a malformed host key, while a server could panic if either
PublicKeyCallback accepts a malformed public key, or if IsUserAuthority accepts
a certificate with a malformed public key.

The issue is CVE-2019-17596 and Go issue golang.org/issue/34960.

Thanks to Daniel Mandragona for discovering and reporting this issue. We'd also
like to thank regilero for a previous disclosure of CVE-2019-16276.

The Go 1.13.2 release also includes a fix to the compiler that prevents improper
access to negative slice indexes in rare cases. Affected code, in which the
compiler can prove that the index is zero or negative, would have resulted in a
panic in Go 1.12, but could have led to arbitrary memory read and writes in Go
1.13 and Go 1.13.1. This is Go issue golang.org/issue/34802.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.appveyor.yml

@@ -12,7 +12,7 @@ environment:
   GOPATH: C:\gopath
   CGO_ENABLED: 1
   matrix:
-    - GO_VERSION: 1.12.10
+    - GO_VERSION: 1.12.12
 
 before_build:
   - choco install -y mingw --version 5.3.0

contrib/Dockerfile.test

@@ -6,7 +6,7 @@
 # 3.) $ make binaries install test
 #
 
-ARG GOLANG_VERSION=1.12
+ARG GOLANG_VERSION=1.12.12
 
 FROM golang:${GOLANG_VERSION} AS golang-base
 RUN mkdir -p /go/src/github.com/containerd/containerd