From 7f2d3f2c5c783dfacc7bc3bb86da4008d8b61bd6 Mon Sep 17 00:00:00 2001
From: Anton Averchenkov <84287187+averche@users.noreply.github.com>
Date: Tue, 30 May 2023 12:23:51 -0400
Subject: [PATCH] fix exitCh race condition (#20817)

---
 command/agent/exec/exec.go | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/command/agent/exec/exec.go b/command/agent/exec/exec.go
index fa91003964..a1ea97addc 100644
--- a/command/agent/exec/exec.go
+++ b/command/agent/exec/exec.go
@@ -257,7 +257,16 @@ func (s *Server) bounceCmd(newEnvVars []string) error {
 	}
 	s.childProcess = proc
 
-	// listen if the child process exits and bubble it up to the main loop
+	if err := s.childProcess.Start(); err != nil {
+		return fmt.Errorf("error starting the child process: %w", err)
+	}
+
+	s.childProcessState = childProcessStateRunning
+
+	// Listen if the child process exits and bubble it up to the main loop.
+	//
+	// NOTE: this must be invoked after child.Start() to avoid a potential
+	// race condition with ExitCh not being initialized.
 	go func() {
 		ctx, cancel := context.WithCancel(context.Background())
 		s.childProcessExitCodeCloser = cancel
@@ -270,10 +279,5 @@ func (s *Server) bounceCmd(newEnvVars []string) error {
 		}
 	}()
 
-	if err := s.childProcess.Start(); err != nil {
-		return fmt.Errorf("error starting child process: %w", err)
-	}
-	s.childProcessState = childProcessStateRunning
-
 	return nil
 }