From 0913090f3a332f569bc4044be9cd8e54eb726a01 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Trevisan=20=28Trevi=C3=B1o=29?= <mail@3v1n0.net>
Date: Wed, 22 Jul 2026 17:19:51 +0200
Subject: [PATCH] pam/gdm/extension: Use upstream macros to cleanup the JSON
 request

This is what we were doing manually, as the APIs were not exposed.

Use the new upstream code for this
---
 pam/internal/gdm/extension.go                 |  3 +--
 pam/internal/gdm/extension.h                  |  6 ++++++
 .../gdm-custom-json-pam-extension.h           |  9 ++++++++
 .../extensions/gdm-pam-extensions-common.h    | 21 +++++++++++++++++++
 4 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/pam/internal/gdm/extension.go b/pam/internal/gdm/extension.go
index 0e047378ee..3e7eb254b7 100644
--- a/pam/internal/gdm/extension.go
+++ b/pam/internal/gdm/extension.go
@@ -122,8 +122,7 @@ func (msg *jsonProtoMessage) release() {
 		return
 	}
 
-	C.free(unsafe.Pointer(msg.json))
-	C.free(unsafe.Pointer(msg))
+	C.gdm_custom_json_request_free((*C.GdmPamExtensionJSONProtocol)(msg))
 }
 
 func (msg *jsonProtoMessage) protoName() string {
diff --git a/pam/internal/gdm/extension.h b/pam/internal/gdm/extension.h
index 20e36aaaff..f2def217bf 100644
--- a/pam/internal/gdm/extension.h
+++ b/pam/internal/gdm/extension.h
@@ -66,3 +66,9 @@ gdm_custom_json_request_is_valid_authd (GdmPamExtensionJSONProtocol *request)
 
   return strncmp (request->protocol_name, JSON_PROTO_NAME, sizeof (request->protocol_name)) == 0;
 }
+
+static inline void
+gdm_custom_json_request_free (GdmPamExtensionJSONProtocol *message)
+{
+  GDM_PAM_EXTENSION_CUSTOM_JSON_RESPONSE_FREE (message);
+}
diff --git a/pam/internal/gdm/extensions/gdm-custom-json-pam-extension.h b/pam/internal/gdm/extensions/gdm-custom-json-pam-extension.h
index 07052cf299..1d23484dae 100644
--- a/pam/internal/gdm/extensions/gdm-custom-json-pam-extension.h
+++ b/pam/internal/gdm/extensions/gdm-custom-json-pam-extension.h
@@ -63,3 +63,12 @@ typedef struct {
 
 #define GDM_PAM_EXTENSION_REPLY_TO_CUSTOM_JSON_RESPONSE(reply) \
         ((GdmPamExtensionJSONProtocol *) (void *) reply->resp)
+
+#define GDM_PAM_EXTENSION_CUSTOM_JSON_RESPONSE_FREE(response) \
+{ \
+        if ((response)->json != NULL) { \
+                gdm_pam_extension_zero_buffer ((response)->json, strlen ((response)->json)); \
+                free ((response)->json); \
+        } \
+        free (response); \
+}
diff --git a/pam/internal/gdm/extensions/gdm-pam-extensions-common.h b/pam/internal/gdm/extensions/gdm-pam-extensions-common.h
index 110226c4e5..4452d33729 100644
--- a/pam/internal/gdm/extensions/gdm-pam-extensions-common.h
+++ b/pam/internal/gdm/extensions/gdm-pam-extensions-common.h
@@ -27,10 +27,31 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <string.h>
+#include <strings.h>
 #include <limits.h>
 
 #include <security/pam_appl.h>
 
+#if (defined(__GLIBC__) && defined(__GLIBC_MINOR__) && \
+    (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 25)) && \
+    (defined(_GNU_SOURCE) || defined(_DEFAULT_SOURCE))) || \
+    defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__APPLE__)
+
+#define gdm_pam_extension_zero_buffer(s, n) do { \
+    explicit_bzero((s), (n)); \
+} while(0)
+
+#else
+
+#define gdm_pam_extension_zero_buffer(s, n) do { \
+    memset((s), 0, (n)); \
+    /* Memory barrier to prevent the compiler from erasing the memset */ \
+    __asm__ __volatile__ ("" : : "r"(s) : "memory"); \
+} while(0)
+
+#endif
+
 typedef struct {
         uint32_t length;