Re: KMSAN: uninit-value in can_receive

[Oliver Hartkopp]

On 19/11/2019 22.09, Eric Dumazet wrote:
> On 11/19/19 12:24 PM, Oliver Hartkopp wrote:
> > Please check commit d3b58c47d330d ("can: replace timestamp as unique skb attribute").
>
> Oh well... This notion of 'unique skb attribute' is interesting...

Yes. The problem is that the joined filter needs to detect the identical 
skb which is delivered several times to raw_rcv() to process filters 
that are logical ANDed.

> > can_skb_prv(skb)->skbcnt is set to 0 at skb creation time when sending CAN frames from local host or receiving CAN frames from a real CAN interface.
>
> We can not enforce this to happen with a virtual interface.

You are right. I just discovered that I'm not able to send CAN frames 
via PF_PACKET sockets anymore.

Receiving with a simple test program and Wireshark is fine - but sending 
does not work. PF_PACKET is not creating the same kind of skbs as e.g. 
the CAN_RAW socket does.

So the KMSAN detection was right at the end :-(

I'll take a closer look to enable PF_PACKET to send CAN frames again 
which will fix up the entire  problem.

Thanks for your feedback!

Best,
Oliver