On 11.05.2022 15:24:21, Marc Kleine-Budde wrote: > On 11.05.2022 14:38:32, Oliver Hartkopp wrote: > > IMO this patch does not work as intended. > > > > You probably need to revisit every place where can_skb_reserve() is used, > > e.g. in raw_sendmsg(). > > And the loopback for devices that don't support IFF_ECHO: > > | https://elixir.bootlin.com/linux/latest/source/net/can/af_can.c#L257 BTW: There is a bug with interfaces that don't support IFF_ECHO. Assume an invalid CAN frame is passed to can_send() on an interface that doesn't support IFF_ECHO. The above mentioned code does happily generate an echo frame and it's send, even if the driver drops it, due to can_dropped_invalid_skb(dev, skb). The echoed back CAN frame is treated in raw_rcv() as if the headroom is valid: | https://elixir.bootlin.com/linux/v5.17.6/source/net/can/raw.c#L138 But as far as I can see the can_skb_headroom_valid() check never has been done. What about this patch? index 1fb49d51b25d..fda4807ad165 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -255,6 +255,9 @@ int can_send(struct sk_buff *skb, int loop) */ if (!(skb->dev->flags & IFF_ECHO)) { + if (can_dropped_invalid_skb(dev, skb)) + return -EINVAL; + /* If the interface is not capable to do loopback * itself, we do it here. */ 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 |
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