netdev - Re: [PATCH 1/1] ipv6: Check AF_UNSPEC in ip6_route_multipath

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Message-ID: <0c3291b0-ab8a-4958-b317-ffdafe61b332@redhat.com>
Date: Tue, 12 Aug 2025 10:16:59 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Maksimilijan Marosevic <maksimilijan.marosevic@...ton.me>,
 davem@...emloft.net, dsahern@...nel.org
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-kernel-mentees@...ts.linux.dev,
 syzbot+a259a17220263c2d73fc@...kaller.appspotmail.com
Subject: Re: [PATCH 1/1] ipv6: Check AF_UNSPEC in ip6_route_multipath_add()

On 8/4/25 10:42 PM, Maksimilijan Marosevic wrote:
> This check was removed in commit e6f497955fb6 ("ipv6: Check GATEWAY
> in rtm_to_fib6_multipath_config().") as part of rt6_qualify_for ecmp().
> The author correctly recognises that rt6_qualify_for_ecmp() returns
> false if fb_nh_gw_family is set to AF_UNSPEC, but then mistakes
> AF_UNSPEC for AF_INET6 when reasoning that the check is unnecessary.
> This means certain malformed entries don't get caught in
> ip6_route_multipath_add().
> 
> This patch reintroduces the AF_UNSPEC check while respecting changes
> of the initial patch.
> 
> Reported-by: syzbot+a259a17220263c2d73fc@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=a259a17220263c2d73fc
> Fixes: e6f497955fb6 ("ipv6: Check GATEWAY in rtm_to_fib6_multipath_config().")
> Signed-off-by: Maksimilijan Marosevic <maksimilijan.marosevic@...ton.me>

Please resend in a 2 patches series including an additional self-test as
asked by David.

Also please insert into the subj prefix the target tree ('net' in this
case) and add Kuniyuki into the CC list.

Thanks,

Paolo