Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.10.3 windows/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

set GOARCH=amd64
set GOBIN=
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GORACE=
set GOTMPDIR=
set GCCGO=gccgo
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config

What did you do?

package main

import (
	"strings"

	"golang.org/x/net/html"
)

func main() {
	r := strings.NewReader("<table><math><select><mi><select></table>")
	html.Parse(r)
}

What did you expect to see?

graceful exit

What did you see instead?

An infinite loop