Re: [PATCH net v3] net: ipv6: Fix a bug in ndisc_send_ns when netdev only has a global address

[David Miller]

From: Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx>
Date: Wed, 31 Jul 2019 09:52:52 +0800

> When the egress interface does not have a link local address, it can
> not communicate with other hosts.
> 
> In RFC4861, 7.2.2 says
> "If the source address of the packet prompting the solicitation is the
> same as one of the addresses assigned to the outgoing interface, that
> address SHOULD be placed in the IP Source Address of the outgoing
> solicitation.  Otherwise, any one of the addresses assigned to the
> interface should be used."
> 
> In this patch we try get a global address if we get ll address failed.
> 
> Signed-off-by: Su Yanjun <suyj.fnst@xxxxxxxxxxxxxx>
> ---
> Changes since V2:
> 	- Let banned_flags under the scope of its use.

I do not want to apply this.

The only situation where this can occur is when userland is managing the
interface addresses and has failed to properly add a link local address.

That is a failure by userspace to uphold it's responsibilites when it
has taken over management of these issues, not a situation the kernel
should handle.

Sorry.