From 302e8b6d02dc9ccac00284b3cdf9a69c001882c0 Mon Sep 17 00:00:00 2001
From: zeripath <art27@cantab.net>
Date: Wed, 30 Jun 2021 21:07:23 +0100
Subject: [PATCH] Prevent zombie processes (#16314)

Unfortunately go doesn't always ensure that execd processes are completely
waited for. On linux this means that zombie processes can occur.

This PR ensures that these are waited for by using signal notifier in serv and
passing a context elsewhere.

Signed-off-by: Andrew Thornton <art27@cantab.net>
---
 cmd/serv.go                         | 26 ++++++++++++++++++++++++--
 modules/markup/external/external.go | 10 +++++++++-
 modules/ssh/ssh.go                  |  2 +-
 3 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/cmd/serv.go b/cmd/serv.go
index 1c9f5dc44..40f8b89c9 100644
--- a/cmd/serv.go
+++ b/cmd/serv.go
@@ -6,14 +6,17 @@
 package cmd
 
 import (
+	"context"
 	"fmt"
 	"net/http"
 	"net/url"
 	"os"
 	"os/exec"
+	"os/signal"
 	"regexp"
 	"strconv"
 	"strings"
+	"syscall"
 	"time"
 
 	"code.gitea.io/gitea/models"
@@ -273,12 +276,31 @@ func runServ(c *cli.Context) error {
 		verb = strings.Replace(verb, "-", " ", 1)
 	}
 
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	go func() {
+		// install notify
+		signalChannel := make(chan os.Signal, 1)
+
+		signal.Notify(
+			signalChannel,
+			syscall.SIGINT,
+			syscall.SIGTERM,
+		)
+		select {
+		case <-signalChannel:
+		case <-ctx.Done():
+		}
+		cancel()
+		signal.Reset()
+	}()
+
 	var gitcmd *exec.Cmd
 	verbs := strings.Split(verb, " ")
 	if len(verbs) == 2 {
-		gitcmd = exec.Command(verbs[0], verbs[1], repoPath)
+		gitcmd = exec.CommandContext(ctx, verbs[0], verbs[1], repoPath)
 	} else {
-		gitcmd = exec.Command(verb, repoPath)
+		gitcmd = exec.CommandContext(ctx, verb, repoPath)
 	}
 
 	gitcmd.Dir = setting.RepoRootPath
diff --git a/modules/markup/external/external.go b/modules/markup/external/external.go
index c849f505e..e35a1b99c 100644
--- a/modules/markup/external/external.go
+++ b/modules/markup/external/external.go
@@ -5,6 +5,7 @@
 package external
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -15,6 +16,7 @@ import (
 
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/markup"
+	"code.gitea.io/gitea/modules/process"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
 )
@@ -96,7 +98,13 @@ func (p *Renderer) Render(ctx *markup.RenderContext, input io.Reader, output io.
 		args = append(args, f.Name())
 	}
 
-	cmd := exec.Command(commands[0], args...)
+	processCtx, cancel := context.WithCancel(ctx.Ctx)
+	defer cancel()
+
+	pid := process.GetManager().Add(fmt.Sprintf("Render [%s] for %s", commands[0], ctx.URLPrefix), cancel)
+	defer process.GetManager().Remove(pid)
+
+	cmd := exec.CommandContext(processCtx, commands[0], args...)
 	cmd.Env = append(
 		os.Environ(),
 		"GITEA_PREFIX_SRC="+ctx.URLPrefix,
diff --git a/modules/ssh/ssh.go b/modules/ssh/ssh.go
index bcaae5a18..c0897377c 100644
--- a/modules/ssh/ssh.go
+++ b/modules/ssh/ssh.go
@@ -66,7 +66,7 @@ func sessionHandler(session ssh.Session) {
 
 	args := []string{"serv", "key-" + keyID, "--config=" + setting.CustomConf}
 	log.Trace("SSH: Arguments: %v", args)
-	cmd := exec.Command(setting.AppPath, args...)
+	cmd := exec.CommandContext(session.Context(), setting.AppPath, args...)
 	cmd.Env = append(
 		os.Environ(),
 		"SSH_ORIGINAL_COMMAND="+command,