From: Ido Schimmel <idosch@nvidia.com>
To: Kuniyuki Iwashima <kuniyu@google.com>
Cc: David Ahern <dsahern@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
Kuniyuki Iwashima <kuni1840@gmail.com>,
netdev@vger.kernel.org
Subject: Re: [PATCH v1 net] ipv4: fib: Don't ignore error route in local/main tables.
Date: Mon, 22 Jun 2026 10:05:49 +0300 [thread overview]
Message-ID: <20260622070549.GA89414@shredder> (raw)
In-Reply-To: <20260619212753.3367244-1-kuniyu@google.com>
On Fri, Jun 19, 2026 at 09:27:20PM +0000, Kuniyuki Iwashima wrote:
> When CONFIG_IP_MULTIPLE_TABLES is enabled but no rule is added,
> fib_lookup() performs route lookup directly on two tables.
>
> Since the first lookup does not properly bail out, the result
> of an error route in the merged local/main table could be
> overwritten by another route in the default table:
>
> # unshare -n
> # ip link set lo up
> # ip route add 192.168.0.0/24 dev lo table 253
> # ip route add unreachable 192.168.0.0/24
> # ip route get 192.168.0.1
> 192.168.0.1 dev lo table default uid 0
> cache <local>
>
> Once a random rule is added, the error route is respected:
>
> # ip rule add table 0
> # ip rule del table 0
> # ip route get 192.168.0.1
> RTNETLINK answers: No route to host
>
> Let's fix the inconsistent behaviour.
>
> Fixes: f4530fa574df ("ipv4: Avoid overhead when no custom FIB rules are installed.")
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
prev parent reply other threads:[~2026-06-22 7:06 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-19 21:27 [PATCH v1 net] ipv4: fib: Don't ignore error route in local/main tables Kuniyuki Iwashima
2026-06-22 7:05 ` Ido Schimmel [this message]
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