From c7cd606f60e7679c7f9eee7010f02a6f000209c1 Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Sat, 12 Dec 2009 04:13:21 +0000 Subject: [PATCH] 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 Signed-off-by: Wolfgang Grandegger Signed-off-by: David S. Miller --- drivers/net/can/at91_can.c | 2 +- drivers/net/can/bfin_can.c | 2 +- drivers/net/can/mcp251x.c | 13 +++---------- drivers/net/can/mscan/mscan.c | 3 ++- drivers/net/can/sja1000/sja1000.c | 18 ++++++++---------- drivers/net/can/ti_hecc.c | 2 +- drivers/net/can/usb/ems_usb.c | 2 +- include/linux/can/dev.h | 9 +++++++++ 8 files changed, 26 insertions(+), 25 deletions(-) diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c index cbe3fce53e3b..d0ec17878ffc 100644 --- a/drivers/net/can/at91_can.c +++ b/drivers/net/can/at91_can.c @@ -474,7 +474,7 @@ static void at91_read_mb(struct net_device *dev, unsigned int mb, reg_msr = at91_read(priv, AT91_MSR(mb)); if (reg_msr & AT91_MSR_MRTR) cf->can_id |= CAN_RTR_FLAG; - cf->can_dlc = min_t(__u8, (reg_msr >> 16) & 0xf, 8); + cf->can_dlc = get_can_dlc((reg_msr >> 16) & 0xf); *(u32 *)(cf->data + 0) = at91_read(priv, AT91_MDL(mb)); *(u32 *)(cf->data + 4) = at91_read(priv, AT91_MDH(mb)); diff --git a/drivers/net/can/bfin_can.c b/drivers/net/can/bfin_can.c index c7fc1de28173..0ec1524523cc 100644 --- a/drivers/net/can/bfin_can.c +++ b/drivers/net/can/bfin_can.c @@ -392,7 +392,7 @@ static void bfin_can_rx(struct net_device *dev, u16 isrc) 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) { diff --git a/drivers/net/can/mcp251x.c b/drivers/net/can/mcp251x.c index 78b1b69b2921..9c5a1537939c 100644 --- a/drivers/net/can/mcp251x.c +++ b/drivers/net/can/mcp251x.c @@ -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++; diff --git a/drivers/net/can/mscan/mscan.c b/drivers/net/can/mscan/mscan.c index bb06dfb58f25..07346f880ca6 100644 --- a/drivers/net/can/mscan/mscan.c +++ b/drivers/net/can/mscan/mscan.c @@ -297,7 +297,8 @@ static void mscan_get_rx_frame(struct net_device *dev, struct can_frame *frame) frame->can_id |= can_id >> 1; if (can_id & 1) frame->can_id |= CAN_RTR_FLAG; - frame->can_dlc = in_8(®s->rx.dlr) & 0xf; + + frame->can_dlc = get_can_dlc(in_8(®s->rx.dlr) & 0xf); if (!(frame->can_id & CAN_RTR_FLAG)) { void __iomem *data = ®s->rx.dsr1_0; diff --git a/drivers/net/can/sja1000/sja1000.c b/drivers/net/can/sja1000/sja1000.c index b4ba88a31075..542a4f7255b4 100644 --- a/drivers/net/can/sja1000/sja1000.c +++ b/drivers/net/can/sja1000/sja1000.c @@ -293,15 +293,14 @@ static void sja1000_rx(struct net_device *dev) uint8_t fi; uint8_t dreg; canid_t id; - uint8_t dlc; int i; + /* create zero'ed CAN frame buffer */ skb = alloc_can_skb(dev, &cf); if (skb == NULL) return; fi = priv->read_reg(priv, REG_FI); - dlc = fi & 0x0F; if (fi & FI_FF) { /* extended frame format (EFF) */ @@ -318,16 +317,15 @@ static void sja1000_rx(struct net_device *dev) | (priv->read_reg(priv, REG_ID2) >> 5); } - if (fi & FI_RTR) + if (fi & FI_RTR) { id |= CAN_RTR_FLAG; + } else { + cf->can_dlc = get_can_dlc(fi & 0x0F); + for (i = 0; i < cf->can_dlc; i++) + cf->data[i] = priv->read_reg(priv, dreg++); + } cf->can_id = id; - cf->can_dlc = dlc; - for (i = 0; i < dlc; i++) - cf->data[i] = priv->read_reg(priv, dreg++); - - while (i < 8) - cf->data[i++] = 0; /* release receive buffer */ priv->write_reg(priv, REG_CMR, CMD_RRB); @@ -335,7 +333,7 @@ static void sja1000_rx(struct net_device *dev) netif_rx(skb); stats->rx_packets++; - stats->rx_bytes += dlc; + stats->rx_bytes += cf->can_dlc; } static int sja1000_err(struct net_device *dev, uint8_t isrc, uint8_t status) diff --git a/drivers/net/can/ti_hecc.c b/drivers/net/can/ti_hecc.c index 07e8016b17ec..5c993c2da528 100644 --- a/drivers/net/can/ti_hecc.c +++ b/drivers/net/can/ti_hecc.c @@ -552,7 +552,7 @@ static int ti_hecc_rx_pkt(struct ti_hecc_priv *priv, int mbxno) data = hecc_read_mbx(priv, mbxno, HECC_CANMCF); if (data & HECC_CANMCF_RTR) cf->can_id |= CAN_RTR_FLAG; - cf->can_dlc = data & 0xF; + cf->can_dlc = get_can_dlc(data & 0xF); data = hecc_read_mbx(priv, mbxno, HECC_CANMDL); *(u32 *)(cf->data) = cpu_to_be32(data); if (cf->can_dlc > 4) { diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c index 591eb0eb1c2b..efbb05c71bf4 100644 --- a/drivers/net/can/usb/ems_usb.c +++ b/drivers/net/can/usb/ems_usb.c @@ -316,7 +316,7 @@ static void ems_usb_rx_can_msg(struct ems_usb *dev, struct ems_cpc_msg *msg) return; cf->can_id = le32_to_cpu(msg->msg.can_msg.id); - cf->can_dlc = min_t(u8, msg->msg.can_msg.length, 8); + cf->can_dlc = get_can_dlc(msg->msg.can_msg.length & 0xF); if (msg->type == CPC_MSG_TYPE_EXT_CAN_FRAME || msg->type == CPC_MSG_TYPE_EXT_RTR_FRAME) 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); -- 2.20.1