> -----Original Message----- > From: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> > Sent: 2020年10月21日 15:21 > To: Joakim Zhang <qiangqing.zhang@xxxxxxx>; Vincent MAILHOL > <mailhol.vincent@xxxxxxxxxx>; Oliver Hartkopp <socketcan@xxxxxxxxxxxx>; > linux-can@xxxxxxxxxxxxxxx > Cc: kernel@xxxxxxxxxxxxxx; Stéphane Grosjean > <s.grosjean@xxxxxxxxxxxxxxx> > Subject: Re: [net-rfc 04/16] can: dev: can_get_len(): add a helper function to > get the correct length of Classical frames > > On 10/21/20 9:11 AM, Joakim Zhang wrote: > > I wonder if it's appropriate to ask this question here, why this > > RAW_DLC issue might run into some buffer overflow issue? Will it cause > > frames dropped finally? > > On the wire the dlc for CAN-2.0 frames ca go from 0...15. In the RX-path the > DLC for CAN-2.0 frames is capped to 8. > > So userspace only ever sees a max dlc of 8. This way you can loop over the > struct can_frame::data. If we pass the dlc of the wire uncapped, you may loop > until 15 :) > > In the TX-path we currently drop CAN-2.0 frames with dlc >8. Thanks Marc, now I understand the meaning of "run into some buffer overflow". 😊 Best Regards, Joakim Zhang > regards, > Marc > > -- > Pengutronix e.K. | Marc Kleine-Budde | > Embedded Linux | https://www.pengutronix.de | > Vertretung West/Dortmund | Phone: +49-231-2826-924 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
