2 files changed, 93 insertions, 1 deletions
diff --git a/pkg/aflow/tool/codeeditor/codeeditor.go b/pkg/aflow/tool/codeeditor/codeeditor.go
index f67abbd69..ce2d7afb7 100644
--- a/pkg/aflow/tool/codeeditor/codeeditor.go
+++ b/pkg/aflow/tool/codeeditor/codeeditor.go
@@ -4,7 +4,11 @@
 package codeeditor
 
 import (
+	"path/filepath"
+	"strings"
+
 	"github.com/google/syzkaller/pkg/aflow"
+	"github.com/google/syzkaller/pkg/osutil"
 )
 
 var Tool = aflow.NewFuncTool("codeeditor", codeeditor, `
@@ -26,7 +30,16 @@ type args struct {
 }
 
 func codeeditor(ctx *aflow.Context, state state, args args) (struct{}, error) {
-	// TODO: check that the SourceFile is not escaping.
+	if strings.Contains(filepath.Clean(args.SourceFile), "..") {
+		return struct{}{}, aflow.BadCallError("SourceFile %q is outside of the source tree", args.SourceFile)
+	}
+	file := filepath.Join(state.KernelScratchSrc, args.SourceFile)
+	if !osutil.IsExist(file) {
+		return struct{}{}, aflow.BadCallError("SourceFile %q does not exist", args.SourceFile)
+	}
+	if strings.TrimSpace(args.CurrentCode) == "" {
+		return struct{}{}, aflow.BadCallError("CurrentCode snippet is empty")
+	}
 	// If SourceFile is incorrect, or CurrentCode is not matched, return aflow.BadCallError
 	// with an explanation. Say that it needs to increase context if CurrentCode is not matched.
 	// Try to do as fuzzy match for CurrentCode as possible (strip line numbers,
diff --git a/pkg/aflow/tool/codeeditor/codeeditor_test.go b/pkg/aflow/tool/codeeditor/codeeditor_test.go
new file mode 100644
index 000000000..4ba556f1b
--- /dev/null
+++ b/pkg/aflow/tool/codeeditor/codeeditor_test.go
@@ -0,0 +1,79 @@
+// Copyright 2026 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package codeeditor
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/google/syzkaller/pkg/aflow"
+	"github.com/google/syzkaller/pkg/osutil"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCodeeditorEscapingPath(t *testing.T) {
+	aflow.TestTool(t, Tool,
+		state{
+			KernelScratchSrc: "whatever",
+		},
+		args{
+			SourceFile: "../../passwd",
+		},
+		struct{}{},
+		`SourceFile "../../passwd" is outside of the source tree`,
+	)
+}
+
+func TestCodeeditorMissingPath(t *testing.T) {
+	aflow.TestTool(t, Tool,
+		state{
+			KernelScratchSrc: t.TempDir(),
+		},
+		args{
+			SourceFile: "missing-file",
+		},
+		struct{}{},
+		`SourceFile "missing-file" does not exist`,
+	)
+}
+
+func TestCodeeditorEmptyCurrentCode(t *testing.T) {
+	dir := writeTestFile(t, "foo", "data")
+	aflow.TestTool(t, Tool,
+		state{
+			KernelScratchSrc: dir,
+		},
+		args{
+			SourceFile: "foo",
+		},
+		struct{}{},
+		`CurrentCode snippet is empty`,
+	)
+}
+
+func writeTestFile(t *testing.T, filename, data string) string {
+	dir := t.TempDir()
+	if err := osutil.WriteFile(filepath.Join(dir, filename), []byte(data)); err != nil {
+		t.Fatal(err)
+	}
+	return dir
+}
+
+func Fuzz(f *testing.F) {
+	dir := f.TempDir()
+	const filename = "src.c"
+	fullFilename := filepath.Join(dir, filename)
+	f.Fuzz(func(t *testing.T, fileData []byte, curCode, newCode string) {
+		require.NoError(t, osutil.WriteFile(fullFilename, fileData))
+		aflow.FuzzTool(t, Tool,
+			state{
+				KernelScratchSrc: dir,
+			},
+			args{
+				SourceFile:  filename,
+				CurrentCode: curCode,
+				NewCode:     newCode,
+			})
+	})
+}