gdbusmessage: Validate type of message header signature field

Parsing a D-Bus message with the signature field in the message header
of type other than ‘g’ (GVariant type signature) would cause a critical
warning. Instead, we should return a runtime error.

Includes a test.

oss-fuzz#9825

Signed-off-by: Philip Withnall <withnall@endlessm.com>
This commit is contained in:
Philip Withnall 2018-08-16 21:33:52 +01:00
parent f148687b02
commit af712bbce1
2 changed files with 75 additions and 0 deletions

View File

@ -2115,6 +2115,15 @@ g_dbus_message_new_from_blob (guchar *blob,
const gchar *signature_str;
gsize signature_str_len;
if (!g_variant_is_of_type (signature, G_VARIANT_TYPE_SIGNATURE))
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_INVALID_ARGUMENT,
_("Signature header found but is not of type signature"));
goto out;
}
signature_str = g_variant_get_string (signature, &signature_str_len);
/* signature but no body */
@ -2695,6 +2704,16 @@ g_dbus_message_to_blob (GDBusMessage *message,
body_start_offset = mbuf.valid_len;
signature = g_dbus_message_get_header (message, G_DBUS_MESSAGE_HEADER_FIELD_SIGNATURE);
if (signature != NULL && !g_variant_is_of_type (signature, G_VARIANT_TYPE_SIGNATURE))
{
g_set_error_literal (error,
G_IO_ERROR,
G_IO_ERROR_INVALID_ARGUMENT,
_("Signature header found but is not of type signature"));
goto out;
}
signature_str = NULL;
if (signature != NULL)
signature_str = g_variant_get_string (signature, NULL);

View File

@ -873,6 +873,20 @@ message_serialize_header_checks (void)
g_assert (blob == NULL);
g_object_unref (message);
/*
* check that we can't serialize messages with SIGNATURE set to a non-signature-typed value
*/
message = g_dbus_message_new_signal ("/the/path", "The.Interface", "TheMember");
g_dbus_message_set_header (message, G_DBUS_MESSAGE_HEADER_FIELD_SIGNATURE, g_variant_new_boolean (FALSE));
blob = g_dbus_message_to_blob (message, &blob_size, G_DBUS_CAPABILITY_FLAGS_NONE, &error);
g_assert_error (error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT);
g_assert_cmpstr (error->message, ==, "Signature header found but is not of type signature");
g_assert_null (blob);
g_clear_error (&error);
g_clear_object (&message);
/*
* check we can't serialize signal messages with INTERFACE, PATH or MEMBER unset / set to reserved value
*/
@ -1083,6 +1097,46 @@ test_double_array (void)
/* ---------------------------------------------------------------------------------------------------- */
/* Test that an invalid header in a D-Bus message (specifically, with a type
* which doesnt match whats expected for the given header) is gracefully
* handled with an error rather than a crash.
* The set of bytes here come directly from fuzzer output. */
static void
test_message_parse_non_signature_header (void)
{
const guint8 data[] = {
0x6c, /* byte order */
0x04, /* message type */
0x0f, /* message flags */
0x01, /* major protocol version */
0x00, 0x00, 0x00, 0x00, /* body length */
0x00, 0x00, 0x00, 0xbc, /* message serial */
/* a{yv} of header fields:
* (things start to be invalid below here) */
0x02, 0x00, 0x00, 0x00, /* array length (in bytes) */
G_DBUS_MESSAGE_HEADER_FIELD_SIGNATURE, /* array key */
/* GVariant array value: */
0x04, /* signature length */
'd', 0x00, 0x00, 'F', /* signature (invalid) */
0x00, /* nul terminator */
/* (GVariant array value payload missing) */
/* (message body length missing) */
};
gsize size = sizeof (data);
GDBusMessage *message = NULL;
GError *local_error = NULL;
message = g_dbus_message_new_from_blob ((guchar *) data, size,
G_DBUS_CAPABILITY_FLAGS_NONE,
&local_error);
g_assert_error (local_error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT);
g_assert_null (message);
g_clear_error (&local_error);
}
/* ---------------------------------------------------------------------------------------------------- */
int
main (int argc,
char *argv[])
@ -1102,6 +1156,8 @@ main (int argc,
message_parse_empty_arrays_of_arrays);
g_test_add_func ("/gdbus/message-serialize/double-array", test_double_array);
g_test_add_func ("/gdbus/message-parse/non-signature-header",
test_message_parse_non_signature_header);
return g_test_run();
}