From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AAB6B35DA40; Tue, 21 Jul 2026 19:42:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784662957; cv=none; b=n8/Y+E4tQWqQLx8iv02qQNV8qOejPbkD7yB1nxszK6QEv6NH4r/fPGzEVNKkdMEgtztRBTYasFVAlrzeqPNL7HTiZD9e4Z8UV3G6ebD1uT3aYehVQgYD4RFgTSOvnvVjExJJA5Odt0IBXMpar6CYqRF+L7Ts6KYtOypqqTTjDck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784662957; c=relaxed/simple; bh=wwZn89HIbg9BNjBfgqOVmzGmnmgxJClHlGghZSRKLl0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ixv5MVYM+681VhxSrf/5+6vdmgTdTTWTROr+peW5qnKseHTSmYMAVRhXqrKlQUUbhWHeRzvjFx3cB+7OxMHVbgqvgBf6ON67y1gtC64/k/CMpjZgmFPgdTzNigH0ll7pMsz5RJjAf3zBWuSagvK2lFI8CmMKHzWMQRP06FuLQBI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OtE9pz0A; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="OtE9pz0A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C78D1F000E9; Tue, 21 Jul 2026 19:42:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784662956; bh=SKA4MGfDVHW4LnNbhVd47Bi1qThq4P6an+7NDXefXNY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OtE9pz0AKAp0QKP5ZLy2yikiEAH3xueWQJeRkfKtyLiSj0NtmJfxEHiCGuOAsWv8C S37XmJSxBpXONZnw51jcpHlPMsKyruWnuI0Miew9rqhqardvJYopX91B4D9XSp4XSp 8E/Tr6W8xoR9K7YeDyjQSamaZumqkUsh7RdKWdmg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kuniyuki Iwashima , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 0639/1276] ipv4: fib: Dont ignore error route in local/main tables. Date: Tue, 21 Jul 2026 17:18:02 +0200 Message-ID: <20260721152500.410783985@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152446.065700225@linuxfoundation.org> References: <20260721152446.065700225@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit b72f0db64205d9ce462038ba995d5d31eff32dc1 ] 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 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 Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260619212753.3367244-1-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/ip_fib.h | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h index 339b92cd5cec69..50060441fa93b9 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -373,7 +373,7 @@ static inline int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res, unsigned int flags) { struct fib_table *tb; - int err = -ENETUNREACH; + int err = -EAGAIN; flags |= FIB_LOOKUP_NOREF; if (net->ipv4.fib_has_custom_rules) @@ -387,17 +387,16 @@ static inline int fib_lookup(struct net *net, struct flowi4 *flp, if (tb) err = fib_table_lookup(tb, flp, res, flags); - if (!err) + if (err != -EAGAIN) goto out; tb = rcu_dereference_rtnl(net->ipv4.fib_default); if (tb) err = fib_table_lookup(tb, flp, res, flags); -out: if (err == -EAGAIN) err = -ENETUNREACH; - +out: rcu_read_unlock(); return err; -- 2.53.0