From: Stephane Grosjean s.grosjean@peak-system.com

When decoding a buffer received from PCAN-USB, the first timestamp read in a packet is a 16-bit coded time base, and the next ones are an 8-bit offset to this base, regardless of the type of packet read.

This patch corrects a potential loss of synchronization by using a timestamp index read from the buffer, rather than an index of received data packets, to determine on the sizeof the timestamp to be read from the packet being decoded.

Signed-off-by: Stephane Grosjean s.grosjean@peak-system.com Fixes: 46be265d3388 ("can: usb: PEAK-System Technik PCAN-USB specific part") Cc: linux-stable stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- drivers/net/can/usb/peak_usb/pcan_usb.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c index 617da295b6c1..5a66c9f53aae 100644 --- a/drivers/net/can/usb/peak_usb/pcan_usb.c +++ b/drivers/net/can/usb/peak_usb/pcan_usb.c @@ -100,7 +100,7 @@ struct pcan_usb_msg_context { u8 *end; u8 rec_cnt; u8 rec_idx; - u8 rec_data_idx; + u8 rec_ts_idx; struct net_device *netdev; struct pcan_usb *pdev; }; @@ -547,10 +547,15 @@ static int pcan_usb_decode_status(struct pcan_usb_msg_context *mc, mc->ptr += PCAN_USB_CMD_ARGS;

if (status_len & PCAN_USB_STATUSLEN_TIMESTAMP) { - int err = pcan_usb_decode_ts(mc, !mc->rec_idx); + int err = pcan_usb_decode_ts(mc, !mc->rec_ts_idx);

if (err) return err; + + /* Next packet in the buffer will have a timestamp on a single + * byte + */ + mc->rec_ts_idx++; }

switch (f) { @@ -632,10 +637,13 @@ static int pcan_usb_decode_data(struct pcan_usb_msg_context *mc, u8 status_len)

cf->can_dlc = get_can_dlc(rec_len);

- /* first data packet timestamp is a word */ - if (pcan_usb_decode_ts(mc, !mc->rec_data_idx)) + /* Only first packet timestamp is a word */ + if (pcan_usb_decode_ts(mc, !mc->rec_ts_idx)) goto decode_failed;

+ /* Next packet in the buffer will have a timestamp on a single byte */ + mc->rec_ts_idx++; + /* read data */ memset(cf->data, 0x0, sizeof(cf->data)); if (status_len & PCAN_USB_STATUSLEN_RTR) { @@ -688,7 +696,6 @@ static int pcan_usb_decode_msg(struct peak_usb_device *dev, u8 *ibuf, u32 lbuf) /* handle normal can frames here */ } else { err = pcan_usb_decode_data(&mc, sl); - mc.rec_data_idx++; } }