From ea6a84f336d5bb7e2ccab04cc6b2a4b2722b503d Mon Sep 17 00:00:00 2001 From: Clayton O'Neill Date: Wed, 11 Nov 2015 20:11:24 +0000 Subject: [PATCH] Fix apt_key tempfile race condition The Ruby Tempfile class has a finalizer that removes the file when the GC runs. It's not predictible when the GC will run, so you have to ensure that the instance of the class stays in scope for as long as you need it. Unfortunately the tempfile method is returning just the filename of the temporary file, which means it goes out of scope when that method returns. This allows the GC to reap it at any time after return. In both CI and production environments we've seen this race fail, causing apt-key add to fail a small (2-3%) amount of the time. This changes the tempfile and source_to_file methods to return the underlying Tempfile object, pushing it up into the caller's scope. Both of the callers immediately use the object to get its filename and then open the file, eliminating the race. Tested this by adding 'GC.start; sleep(1)' immediately before the command is run, to give the GC plenty of time to remove the tempfile if it was going to. --- lib/puppet/provider/apt_key/apt_key.rb | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/lib/puppet/provider/apt_key/apt_key.rb b/lib/puppet/provider/apt_key/apt_key.rb index f8c7d19..a6d68b1 100644 --- a/lib/puppet/provider/apt_key/apt_key.rb +++ b/lib/puppet/provider/apt_key/apt_key.rb @@ -118,7 +118,13 @@ Puppet::Type.type(:apt_key).provide(:apt_key) do parsedValue = URI::parse(value) if parsedValue.scheme.nil? fail("The file #{value} does not exist") unless File.exists?(value) - value + # Because the tempfile method has to return a live object to prevent GC + # of the underlying file from occuring too early, we also have to return + # a file object here. The caller can still call the #path method on the + # closed file handle to get the path. + f = File.open(value, 'r') + f.close + f else begin key = parsedValue.read @@ -132,6 +138,9 @@ Puppet::Type.type(:apt_key).provide(:apt_key) do end end + # The tempfile method needs to return the tempfile object to the caller, so + # that it doesn't get deleted by the GC immediately after it returns. We + # want the caller to control when it goes out of scope. def tempfile(content) file = Tempfile.new('apt_key') file.write content @@ -155,7 +164,7 @@ Puppet::Type.type(:apt_key).provide(:apt_key) do warning('/usr/bin/gpg cannot be found for verification of the id.') end end - file.path + file end def exists? @@ -173,9 +182,11 @@ Puppet::Type.type(:apt_key).provide(:apt_key) do end command.push('--recv-keys', resource[:id]) elsif resource[:content] - command.push('add', tempfile(resource[:content])) + key_file = tempfile(resource[:content]) + command.push('add', key_file.path) elsif resource[:source] - command.push('add', source_to_file(resource[:source])) + key_file = source_to_file(resource[:source]) + command.push('add', key_file.path) # In case we really screwed up, better safe than sorry. else fail("an unexpected condition occurred while trying to add the key: #{resource[:id]}")