From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Grandegger Subject: Re: [PATCH net-2.6] can: Fix data length code handling in rx path Date: Sat, 12 Dec 2009 19:09:54 +0100 Message-ID: <4B23DC72.6030307@grandegger.com> References: <4B23A501.9000208@hartkopp.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: SocketCAN Core Mailing List , Linux Netdev List , David Miller To: Oliver Hartkopp Return-path: In-Reply-To: <4B23A501.9000208-fJ+pQTUTwRTk1uMJSBkQmQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: socketcan-core-bounces-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org Errors-To: socketcan-core-bounces-0fE9KPoRgkgATYTw5x5z8w@public.gmane.org List-Id: netdev.vger.kernel.org Oliver Hartkopp wrote: > A valid CAN dataframe can have a data length code (DLC) of 0 .. 8 data bytes. > > When reading the CAN controllers register the 4-bit value may contain values > from 0 .. 15 which may exceed the reserved space in the socket buffer! > > The ISO 11898-1 Chapter 8.4.2.3 (DLC field) says that register values > 8 > should be reduced to 8 without any error reporting or frame drop. > > This patch introduces a new helper macro to cast a given 4-bit data length > code (dlc) to __u8 and ensure the DLC value to be max. 8 bytes. > > The different handlings in the rx path of the CAN netdevice drivers are fixed. > > Signed-off-by: Oliver Hartkopp Signed-off-by: Wolfgang Grandegger Thanks, Wolfgang.