From 9af48e576487c8b7dd00d6f8c4769cfaf7dcda33 Mon Sep 17 00:00:00 2001
From: Jeff Bonhag <jbonhag@hashicorp.com>
Date: Fri, 26 Jun 2020 13:25:59 -0400
Subject: [PATCH] Raise an error on nil exit status

This commit changes the SSH communicator to raise an error if Vagrant
doesn't receive an exit status from an SSH command, for example if the
command is terminated by the OOM-killer.
---
 lib/vagrant/errors.rb                                    | 4 ++++
 plugins/communicators/ssh/communicator.rb                | 5 +++++
 templates/locales/en.yml                                 | 5 +++++
 test/unit/plugins/communicators/ssh/communicator_test.rb | 9 +++++++++
 4 files changed, 23 insertions(+)

diff --git a/lib/vagrant/errors.rb b/lib/vagrant/errors.rb
index 05e821bba..cdb365bf0 100644
--- a/lib/vagrant/errors.rb
+++ b/lib/vagrant/errors.rb
@@ -796,6 +796,10 @@ module Vagrant
       error_key(:ssh_key_type_not_supported)
     end
 
+    class SSHNoExitStatus < VagrantError
+      error_key(:ssh_no_exit_status)
+    end
+
     class SSHNoRoute < VagrantError
       error_key(:ssh_no_route)
     end
diff --git a/plugins/communicators/ssh/communicator.rb b/plugins/communicators/ssh/communicator.rb
index da43cb23e..80a2c108c 100644
--- a/plugins/communicators/ssh/communicator.rb
+++ b/plugins/communicators/ssh/communicator.rb
@@ -729,6 +729,11 @@ module VagrantPlugins
           yield :stdout, data if block_given?
         end
 
+        if !exit_status
+          @logger.debug("Exit status: #{exit_status.inspect}")
+          raise Vagrant::Errors::SSHNoExitStatus
+        end
+
         # Return the final exit status
         return exit_status
       end
diff --git a/templates/locales/en.yml b/templates/locales/en.yml
index 985006e0d..a961388a2 100644
--- a/templates/locales/en.yml
+++ b/templates/locales/en.yml
@@ -1435,6 +1435,11 @@ en:
         usually indicates that SSH within the guest machine was unable to
         properly start up. Please boot the VM in GUI mode to check whether
         it is booting properly.
+      ssh_no_exit_status: |-
+        The SSH command completed, but Vagrant did not receive an exit status.
+        This indicates that the command was terminated unexpectedly. Please
+        check that the VM has sufficient memory to run the command and that no
+        processes were killed by the guest operating system.
       ssh_no_route: |-
         While attempting to connect with SSH, a "no route to host" (EHOSTUNREACH)
         error was received. Please verify your network settings are correct
diff --git a/test/unit/plugins/communicators/ssh/communicator_test.rb b/test/unit/plugins/communicators/ssh/communicator_test.rb
index d6e9d2b85..f25d93163 100644
--- a/test/unit/plugins/communicators/ssh/communicator_test.rb
+++ b/test/unit/plugins/communicators/ssh/communicator_test.rb
@@ -317,6 +317,15 @@ describe VagrantPlugins::CommunicatorSSH::Communicator do
       end
     end
 
+    context "with no exit code received" do
+      let(:exit_data) { double("exit_data", read_long: nil) }
+
+      it "raises error when exit code is nil" do
+        expect(command_channel).to receive(:send_data).with(/make\n/)
+        expect{ communicator.execute("make") }.to raise_error(Vagrant::Errors::SSHNoExitStatus)
+      end
+    end
+
     context "with garbage content prepended to command output" do
       let(:command_stdout_data) do
         "Line of garbage\nMore garbage\n#{command_garbage_marker}bin\ntmp\n"