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 E9CD634B1A6; Tue, 21 Jul 2026 22:13:35 +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=1784672017; cv=none; b=MZVyntStNWuPnS9tZNJ9KweJ+HYkxLz4DqwlvYJgmhonXt4DbMRqt7IUL2/roEXpsJ9Y3Xo2hgWmVs6in/LZ/S7prBArd/65y2k5hu+KaBUz/y7YZ3JoCTOk8Go+PxR+PevRkX02ADg3z7/ga6rnIRKdzE7R+kH2SiFn+OjzBMI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784672017; c=relaxed/simple; bh=8Us0TWz09azUTrNvL9OfdYmxkG9PdBNc5OXOrr6KfJI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LeFtJ3nn1niiIIKQhI41IBKo2/ZLyoT9zRBE6cy1bEznPmEUgAL5KMQwoRSfPaqzKZLGvWfaIQ3A5DJe0t1kj+ovEFrQKOUpoU2kLkalkTZaIN60jKR1kJyd6dgopKB4as8u7vH0DLK2z4nrNrvtix1UjWZtY1xQcFaVBC7dV1M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=p0eR/dwK; 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="p0eR/dwK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5AACC1F000E9; Tue, 21 Jul 2026 22:13:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784672015; bh=r5FHfGzq2nUd/LeJV+Ml90XAUby68qiBoguiSVnIsQQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=p0eR/dwKeyqfEFtXDCjPHBHR3AGmVEzEYKQM1MXRDnwIq8vft2dGHDmhpuj1/cPLT RoeyUZ2weMhjK58AaDR2nsAEs3deqKwYIx4Vy9VT674+JyB35dFfKQKwCpsCwU4hVo 9etaQBceLshHVXTaJoLL0SuDh+yEsgOwuvwdk/T8= 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 5.15 466/843] ipv4: fib: Dont ignore error route in local/main tables. Date: Tue, 21 Jul 2026 17:21:41 +0200 Message-ID: <20260721152416.519992107@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152405.946368001@linuxfoundation.org> References: <20260721152405.946368001@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 5.15-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 9f6e2a476dc280..718b9799d77d78 100644 --- a/include/net/ip_fib.h +++ b/include/net/ip_fib.h @@ -366,7 +366,7 @@ 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) @@ -380,17 +380,16 @@ 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