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can: peak_usb: fix a potential out-of-sync while decoding packets

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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>
This commit is contained in:
Stephane Grosjean
2019-10-08 10:35:44 +02:00
committed by Marc Kleine-Budde
parent 5e269324db
commit de280f403f
1 changed files with 12 additions and 5 deletions
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17
drivers/net/can/usb/peak_usb/pcan_usb.c
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@ -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++;
}
}