[SECURITY] Test XSS in wiki last commit information

On the wiki and revisions page, information is shown about the last
commit that modified that wiki page. This includes the time it was last
edited and by whom. Verify it is sanitized.

(cherry picked from commit 565e331238)

tests/integration/xss_test.go

@@ -4,14 +4,24 @@
 package integration
 
 import (
+	"context"
+	"fmt"
 	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
 	"testing"
+	"time"
 
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/tests"
 
+	gogit "github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing/object"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestXSSUserFullName(t *testing.T) {
@@ -37,3 +47,68 @@ func TestXSSUserFullName(t *testing.T) {
 		htmlDoc.doc.Find("div.content").Find(".header.text.center").Text(),
 	)
 }
+
+func TestXSSWikiLastCommitInfo(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		// Prepare the environment.
+		dstPath := t.TempDir()
+		r := fmt.Sprintf("%suser2/repo1.wiki.git", u.String())
+		u, err := url.Parse(r)
+		assert.NoError(t, err)
+		u.User = url.UserPassword("user2", userPassword)
+		assert.NoError(t, git.CloneWithArgs(context.Background(), git.AllowLFSFiltersArgs(), u.String(), dstPath, git.CloneRepoOptions{}))
+
+		// Use go-git here, because using git wouldn't work, it has code to remove
+		// `<`, `>` and `\n` in user names. Even though this is permitted and
+		// wouldn't result in a error by a Git server.
+		gitRepo, err := gogit.PlainOpen(dstPath)
+		require.NoError(t, err)
+
+		w, err := gitRepo.Worktree()
+		require.NoError(t, err)
+
+		filename := filepath.Join(dstPath, "Home.md")
+		err = os.WriteFile(filename, []byte("Oh, a XSS attack?"), 0o644)
+		require.NoError(t, err)
+
+		_, err = w.Add("Home.md")
+		require.NoError(t, err)
+
+		_, err = w.Commit("Yay XSS", &gogit.CommitOptions{
+			Author: &object.Signature{
+				Name:  `Gusted<script class="evil">alert('Oh no!');</script>`,
+				Email: "valid@example.org",
+				When:  time.Date(2024, time.January, 31, 0, 0, 0, 0, time.UTC),
+			},
+		})
+		require.NoError(t, err)
+
+		// Push.
+		_, _, err = git.NewCommand(git.DefaultContext, "push").AddArguments(git.ToTrustedCmdArgs([]string{"origin", "master"})...).RunStdString(&git.RunOpts{Dir: dstPath})
+		require.NoError(t, err)
+
+		// Check on page view.
+		t.Run("Page view", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, http.MethodGet, "/user2/repo1/wiki/Home")
+			resp := MakeRequest(t, req, http.StatusOK)
+			htmlDoc := NewHTMLParser(t, resp.Body)
+
+			htmlDoc.AssertElement(t, "script.evil", false)
+			assert.Contains(t, htmlDoc.Find(".ui.sub.header").Text(), `Gusted<script class="evil">alert('Oh no!');</script> edited this page 2024-01-31`)
+		})
+
+		// Check on revisions page.
+		t.Run("Revision page", func(t *testing.T) {
+			defer tests.PrintCurrentTest(t)()
+
+			req := NewRequest(t, http.MethodGet, "/user2/repo1/wiki/Home?action=_revision")
+			resp := MakeRequest(t, req, http.StatusOK)
+			htmlDoc := NewHTMLParser(t, resp.Body)
+
+			htmlDoc.AssertElement(t, "script.evil", false)
+			assert.Contains(t, htmlDoc.Find(".ui.sub.header").Text(), `Gusted<script class="evil">alert('Oh no!');</script> edited this page 2024-01-31`)
+		})
+	})
+}