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Message-ID: <4B23DC72.6030307@grandegger.com>
Date: Sat, 12 Dec 2009 19:09:54 +0100
From: Wolfgang Grandegger <wg@...ndegger.com>
To: Oliver Hartkopp <oliver@...tkopp.net>
CC: David Miller <davem@...emloft.net>,
Linux Netdev List <netdev@...r.kernel.org>,
SocketCAN Core Mailing List <socketcan-core@...ts.berlios.de>
Subject: Re: [PATCH net-2.6] can: Fix data length code handling in rx path
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 <oliver@...tkopp.net>
Signed-off-by: Wolfgang Grandegger <wg@...ndegger.com>
Thanks,
Wolfgang.
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