xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

can: Fix data length code handling in rx path

Browse Source 
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>
This commit is contained in:
Oliver Hartkopp
2009-12-12 04:13:21 +00:00
committed by David S. Miller
parent d90a909e1f
commit c7cd606f60
8 changed files with 26 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/net/can/mcp251x.c
View File

@@ -403,9 +403,8 @@ static void mcp251x_hw_rx_frame(struct spi_device *spi, u8 *buf,
for (i = 1; i < RXBDAT_OFF; i++)
buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
len = buf[RXBDLC_OFF] & RXBDLC_LEN_MASK;
if (len > 8)
len = 8;
len = get_can_dlc(buf[RXBDLC_OFF] & RXBDLC_LEN_MASK);
for (; i < (RXBDAT_OFF + len); i++)
buf[i] = mcp251x_read_reg(spi, RXBCTRL(buf_idx) + i);
} else {
@@ -455,13 +454,7 @@ static void mcp251x_hw_rx(struct spi_device *spi, int buf_idx)
(buf[RXBSIDL_OFF] >> RXBSIDL_SHIFT);
}
/* Data length */
frame->can_dlc = buf[RXBDLC_OFF] & RXBDLC_LEN_MASK;
if (frame->can_dlc > 8) {
dev_warn(&spi->dev, "invalid frame recevied\n");
priv->net->stats.rx_errors++;
dev_kfree_skb(skb);
return;
}
frame->can_dlc = get_can_dlc(buf[RXBDLC_OFF] & RXBDLC_LEN_MASK);
memcpy(frame->data, buf + RXBDAT_OFF, frame->can_dlc);
priv->net->stats.rx_packets++;