Re: [PATCH net 1/2] gre: Fix IPv6 multicast route creation.

[Ido Schimmel <idosch@nvidia.com>]

On Wed, Jul 09, 2025 at 04:30:10PM +0200, Guillaume Nault wrote:
> Use addrconf_add_dev() instead of ipv6_find_idev() in
> addrconf_gre_config() so that we don't just get the inet6_dev, but also
> install the default ff00::/8 multicast route.
> 
> Before commit 3e6a0243ff00 ("gre: Fix again IPv6 link-local address
> generation."), the multicast route was created at the end of the
> function by addrconf_add_mroute(). But this code path is now only taken
> in one particular case (gre devices not bound to a local IP address and
> in EUI64 mode). For all other cases, the function exits early and
> addrconf_add_mroute() is not called anymore.
> 
> Using addrconf_add_dev() instead of ipv6_find_idev() in
> addrconf_gre_config(), fixes the problem as it will create the default
> multicast route for all gre devices. This also brings
> addrconf_gre_config() a bit closer to the normal netdevice IPv6
> configuration code (addrconf_dev_config()).
> 
> Fixes: 3e6a0243ff00 ("gre: Fix again IPv6 link-local address generation.")
> Reported-by: Aiden Yang <ling@moedove.com>
> Closes: https://lore.kernel.org/netdev/CANR=AhRM7YHHXVxJ4DmrTNMeuEOY87K2mLmo9KMed1JMr20p6g@mail.gmail.com/
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Tested-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: Guillaume Nault <gnault@redhat.com>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>