From acb7b0ec69f26a7df10af3992359890b09f076e8 Mon Sep 17 00:00:00 2001
From: Krzesimir Nowak <qdlacz@gmail.com>
Date: Wed, 10 Feb 2021 23:51:07 +0100
Subject: [PATCH] gbytearray: Do not accept too large byte arrays

GByteArray uses guint for storing the length of the byte array, but it
also has a constructor (g_byte_array_new_take) that takes length as a
gsize. gsize may be larger than guint (64 bits for gsize vs 32 bits
for guint). It is possible to call the function with a value greater
than G_MAXUINT, which will result in silent length truncation. This
may happen as a result of unreffing GBytes into GByteArray, so rather
be loud about it.

(Test case tweaked by Philip Withnall.)
[Peter: Fixes CVE-2021-27218, drop test case]
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
---
 glib/garray.c      |  6 ++++++
 glib/gbytes.c      |  4 ++++
 2 files changed, 10 insertions(+), 0 deletion(-)

diff --git a/glib/garray.c b/glib/garray.c
index de720210c..2b66f16a6 100644
--- a/glib/garray.c
+++ b/glib/garray.c
@@ -2261,6 +2261,10 @@ g_byte_array_steal (GByteArray *array,
  * Create byte array containing the data. The data will be owned by the array
  * and will be freed with g_free(), i.e. it could be allocated using g_strdup().
  *
+ * Do not use it if @len is greater than %G_MAXUINT. #GByteArray
+ * stores the length of its data in #guint, which may be shorter than
+ * #gsize.
+ *
  * Since: 2.32
  *
  * Returns: (transfer full): a new #GByteArray
@@ -2272,6 +2276,8 @@ g_byte_array_new_take (guint8 *data,
   GByteArray *array;
   GRealArray *real;
 
+  g_return_val_if_fail (len <= G_MAXUINT, NULL);
+
   array = g_byte_array_new ();
   real = (GRealArray *)array;
   g_assert (real->data == NULL);
diff --git a/glib/gbytes.c b/glib/gbytes.c
index 00fd79155..aaadf451b 100644
--- a/glib/gbytes.c
+++ b/glib/gbytes.c
@@ -519,6 +519,10 @@ g_bytes_unref_to_data (GBytes *bytes,
  * g_bytes_new(), g_bytes_new_take() or g_byte_array_free_to_bytes(). In all
  * other cases the data is copied.
  *
+ * Do not use it if @bytes contains more than %G_MAXUINT
+ * bytes. #GByteArray stores the length of its data in #guint, which
+ * may be shorter than #gsize, that @bytes is using.
+ *
  * Returns: (transfer full): a new mutable #GByteArray containing the same byte data
  *
  * Since: 2.32
-- 
2.20.1