fix: panic in configpatcher when the whole section is missing

smira · smira · commit eb8480c4ce08 · 2026-01-21T16:23:14.000+04:00
Reproducer can be found in testdata, but tl;dr it tries to traverse via `*T` where `T` is a nested struct, and the pointer value is nil. It was seen in the tests with Talos 1.13+ which drops `.machine.network` completely by default. Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com> (cherry picked from commit 415bfae)
diff --git a/pkg/machinery/config/configloader/internal/decoder/selector.go b/pkg/machinery/config/configloader/internal/decoder/selector.go
@@ -141,6 +141,10 @@ func deleteForPath(val reflect.Value, path []string, key, value string) error {
 	}
 
 	if val.Kind() == reflect.Pointer || val.Kind() == reflect.Interface {
+		if val.IsNil() {
+			return ErrLookupFailed
+		}
+
 		return deleteForPath(val.Elem(), path, key, value)
 	}
 
diff --git a/pkg/machinery/config/configpatcher/apply_test.go b/pkg/machinery/config/configpatcher/apply_test.go
@@ -292,3 +292,36 @@ func TestApplyMultiDocCPDelete(t *testing.T) {
 		})
 	}
 }
+
+//go:embed testdata/patchdeletemissing/config.yaml
+var configPatchDeleteMissing []byte
+
+func TestPatchDeleteMissing(t *testing.T) {
+	patches, err := configpatcher.LoadPatches([]string{
+		"@testdata/patchdeletemissing/strategic1.yaml",
+	})
+	require.NoError(t, err)
+
+	cfg, err := configloader.NewFromBytes(configPatchDeleteMissing)
+	require.NoError(t, err)
+
+	for _, tt := range []struct {
+		name  string
+		input configpatcher.Input
+	}{
+		{
+			name:  "WithConfig",
+			input: configpatcher.WithConfig(cfg),
+		},
+		{
+			name:  "WithBytes",
+			input: configpatcher.WithBytes(configPatchDeleteMissing),
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := configpatcher.Apply(tt.input, patches)
+			require.Error(t, err)
+			require.ErrorContains(t, err, `patch delete: path 'machine.network.hostname' in document '/v1alpha1': failed to delete path 'machine.network.hostname': lookup failed`)
+		})
+	}
+}
diff --git a/pkg/machinery/config/configpatcher/testdata/patchdeletemissing/config.yaml b/pkg/machinery/config/configpatcher/testdata/patchdeletemissing/config.yaml
@@ -0,0 +1,2 @@
+version: v1alpha1
+machine: {}
diff --git a/pkg/machinery/config/configpatcher/testdata/patchdeletemissing/strategic1.yaml b/pkg/machinery/config/configpatcher/testdata/patchdeletemissing/strategic1.yaml
@@ -0,0 +1,4 @@
+machine:
+  network:
+    hostname:
+      $patch: delete

Original file line number	Diff line number	Diff line change
`@@ -141,6 +141,10 @@ func deleteForPath(val reflect.Value, path []string, key, value string) error {`
`141`	`141`	`}`
`142`	`142`
`143`	`143`	`if val.Kind() == reflect.Pointer \|\| val.Kind() == reflect.Interface {`
	`144`	`+ if val.IsNil() {`
	`145`	`+ return ErrLookupFailed`
	`146`	`+ }`
	`147`	`+`
`144`	`148`	`return deleteForPath(val.Elem(), path, key, value)`
`145`	`149`	`}`
`146`	`150`