fix: panic if Terraform module references path outside repository. (#…

…2013)

## What this PR does / why we need it:

Fix a panic in the case a Terraform module has module calls with source
outside of the project root directory.

## Which issue(s) this PR fixes:
Fixes #2012 

## Special notes for your reviewer:

## Does this PR introduce a user-facing change?
```
yes, fixes a panic.
```

CHANGELOG.md

@@ -29,6 +29,10 @@ Given a version number `MAJOR.MINOR.PATCH`, we increment the:
   - The API Key configuration has precedence over all other authentication methods.
 - Add support for unprefixed Bitbucket URLs in Terraform `module.source`.
 
+### Fixed
+
+- Fix `terramate list --changed` panic when a Terraform module references a path outside the project root.
+
 ## v0.11.4
 
 ### Added

stack/manager.go

@@ -10,6 +10,7 @@ import (
 	"path"
 	"path/filepath"
 	"sort"
+	"strings"
 
 	"github.com/rs/zerolog/log"
 	"github.com/terramate-io/terramate/config"
@@ -570,6 +571,14 @@ func (m *Manager) tfModuleChanged(
 	}
 
 	modAbsPath := filepath.Join(basedir, mod.Source)
+	rootdir := m.root.Tree().RootDir()
+	if modAbsPath != rootdir && !strings.HasPrefix(modAbsPath, rootdir+string(filepath.Separator)) {
+		printer.Stderr.WarnWithDetails("skipping module call outside of the root directory", errors.E(
+			"module at %q references path %s (abspath %s) outside of the project root",
+			basedir, mod.Source, modAbsPath,
+		))
+		return false, "", nil
+	}
 	modPath := project.PrjAbsPath(m.root.HostDir(), modAbsPath)
 
 	st, err := os.Stat(modAbsPath)

stack/manager_test.go

@@ -145,6 +145,14 @@ func TestListChangedStacks(t *testing.T) {
 				changed: []string{"/stack"},
 			},
 		},
+		{
+			name:        "single stack: dependent module changed has source path outside project root",
+			repobuilder: singleStackDependentModuleChangedWithSourceOutsideRepo,
+			want: listTestResult{
+				list:    []string{"/stack"},
+				changed: []string{},
+			},
+		},
 		{
 			name:        "multiple stack: single module changed",
 			repobuilder: multipleStackOneChangedModule,
@@ -708,6 +716,49 @@ module "module2" {
 	return repo
 }
 
+func singleStackDependentModuleChangedWithSourceOutsideRepo(t *testing.T) repository {
+	repo := singleMergeCommitRepoNoStack(t)
+
+	modules := test.Mkdir(t, repo.Dir, "modules")
+	module1 := test.Mkdir(t, modules, "module1")
+	module2 := test.Mkdir(t, modules, "module2")
+
+	repo.modules = append(repo.modules, module1, module2)
+
+	stack := test.Mkdir(t, repo.Dir, "stack")
+	root, err := config.LoadRoot(repo.Dir)
+	assert.NoError(t, err)
+	createStack(t, root, stack)
+	g := test.NewGitWrapper(t, repo.Dir, []string{})
+
+	test.WriteFile(t, stack, "main.tf", `
+module "module1" {
+	source = "../modules/module1"
+}
+`)
+	test.WriteFile(t, module1, "main.tf", `
+module "module2" {
+	source = "../../../../../../../module2"
+}
+`)
+
+	test.WriteFile(t, module2, "main.tf", `# nothing here`)
+
+	assert.NoError(t, g.Add(repo.Dir), "add files")
+	assert.NoError(t, g.Commit("files"), "commit files")
+	assert.NoError(t, g.Push("origin", "main"))
+
+	assert.NoError(t, g.Checkout("change-module", true))
+
+	test.WriteFile(t, module2, "main.tf", `
+# any change
+`)
+
+	assert.NoError(t, g.Add(repo.Dir), "add main.tf")
+	assert.NoError(t, g.Commit("commit module1/main.tf"), "commit main.tf")
+	return repo
+}
+
 func singleTerragruntStackWithNoChangesRepo(t *testing.T) repository {
 	repo := singleMergeCommitRepoNoStack(t)
 	test.WriteFile(t, repo.Dir, "terramate.tm.hcl", Doc(