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>
diff --git a/drivers/net/can/bfin_can.c b/drivers/net/can/bfin_can.c
index c7fc1de..0ec1524 100644
--- a/drivers/net/can/bfin_can.c
+++ b/drivers/net/can/bfin_can.c
@@ -392,7 +392,7 @@
cf->can_id |= CAN_RTR_FLAG;
/* get data length code */
- cf->can_dlc = bfin_read16(®->chl[obj].dlc);
+ cf->can_dlc = get_can_dlc(bfin_read16(®->chl[obj].dlc) & 0xF);
/* get payload */
for (i = 0; i < 8; i += 2) {