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authorOliver Hartkopp <oliver@hartkopp.net>2009-12-12 07:13:21 +0300
committerDavid S. Miller <davem@davemloft.net>2009-12-14 06:47:42 +0300
commitc7cd606f60e7679c7f9eee7010f02a6f000209c1 (patch)
tree31c19fd7617ede807757b0ae5c29d218587dc43f /include/linux
parentd90a909e1f3e006a1d57fe11fd417173b6494701 (diff)
downloadlinux-c7cd606f60e7679c7f9eee7010f02a6f000209c1.tar.xz
can: Fix data length code handling in rx path
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@hartkopp.net> Signed-off-by: Wolfgang Grandegger <wg@grandegger.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/can/dev.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 1ed2a5cc03f5..3db7767d2a17 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -51,6 +51,15 @@ struct can_priv {
struct sk_buff **echo_skb;
};
+/*
+ * get_can_dlc(value) - helper macro to cast a given data length code (dlc)
+ * to __u8 and ensure the dlc value to be max. 8 bytes.
+ *
+ * To be used in the CAN netdriver receive path to ensure conformance with
+ * ISO 11898-1 Chapter 8.4.2.3 (DLC field)
+ */
+#define get_can_dlc(i) (min_t(__u8, (i), 8))
+
struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max);
void free_candev(struct net_device *dev);