backports: Add a backport of g_memdup2()

g_memdup2() replaces g_memdup(), which is prone to integer overflow on
64-bit systems if copying a very large object with an
attacker-controlled size.

The original version in GLib is extern, but it seems simple enough to
inline a backport.

Related: https://gitlab.gnome.org/GNOME/glib/-/issues/2319
Signed-off-by: Simon McVittie <smcv@collabora.com>

1 files changed, 29 insertions, 5 deletions

diff --git a/glnx-backports.h b/glnx-backports.h
index afab392..f99f08f 100644
--- a/glnx-backports.h
+++ b/glnx-backports.h
@@ -1,8 +1,10 @@
 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
  *
+ * Copyright 1998 Manish Singh
+ * Copyright 1998 Tim Janik
  * Copyright (C) 2015 Colin Walters <walters@verbum.org>
  * Copyright 2017 Emmanuele Bassi
- * SPDX-License-Identifier: LGPL-2.0-or-later
+ * SPDX-License-Identifier: LGPL-2.1-or-later
  * 
  * GLIB - Library of useful routines for C programming
  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
@@ -10,7 +12,7 @@
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
+ * version 2.1 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -18,13 +20,13 @@
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */
 
 #pragma once
 
+#include <string.h>
+
 #include <gio/gio.h>
 
 G_BEGIN_DECLS
@@ -85,6 +87,28 @@ gboolean              glnx_set_object  (GObject **object_ptr,
 #define G_DBUS_METHOD_INVOCATION_UNHANDLED FALSE
 #endif
 
+#if !GLIB_CHECK_VERSION(2, 68, 0)
+static inline gpointer _glnx_memdup2 (gconstpointer mem,
+                                      gsize         byte_size) G_GNUC_ALLOC_SIZE(2);
+static inline gpointer
+_glnx_memdup2 (gconstpointer mem,
+               gsize         byte_size)
+{
+  gpointer new_mem;
+
+  if (mem && byte_size != 0)
+    {
+      new_mem = g_malloc (byte_size);
+      memcpy (new_mem, mem, byte_size);
+    }
+  else
+    new_mem = NULL;
+
+  return new_mem;
+}
+#define g_memdup2 _glnx_memdup2
+#endif
+
 #ifndef G_OPTION_ENTRY_NULL   /* added in 2.70 */
 #define G_OPTION_ENTRY_NULL { NULL, 0, 0, 0, NULL, NULL, NULL }
 #endif