From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C3EFC4332F for ; Mon, 18 Apr 2022 13:57:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245013AbiDROAa (ORCPT ); Mon, 18 Apr 2022 10:00:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244426AbiDRN5Q (ORCPT ); Mon, 18 Apr 2022 09:57:16 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A4B262AE1F; Mon, 18 Apr 2022 06:07:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 4D42BB80EDF; Mon, 18 Apr 2022 13:07:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B381C385A1; Mon, 18 Apr 2022 13:07:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650287240; bh=DIc246/X8wYTM5k2axiagUIBH36M/LUB6zhxhna5S8M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=USEWtSjiZR7TFQ1L//tktJy1xldolqjzfpWY3j0jmNcTZ+y5zIQ5CeknZq1IBwapY wDhS1WxqNYOv/TMPlvLVzKN8PzMUFQLZiGEa5Ne47+i/aIsDen5JEL46lIJX8QYtZU 2m1B/QJndUiYuy5MILkTrKmF2KqMAkNoZIMvn8Ts= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Petr Machata , Ido Schimmel , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.9 100/218] af_netlink: Fix shift out of bounds in group mask calculation Date: Mon, 18 Apr 2022 14:12:46 +0200 Message-Id: <20220418121202.465021832@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121158.636999985@linuxfoundation.org> References: <20220418121158.636999985@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Petr Machata [ Upstream commit 0caf6d9922192dd1afa8dc2131abfb4df1443b9f ] When a netlink message is received, netlink_recvmsg() fills in the address of the sender. One of the fields is the 32-bit bitfield nl_groups, which carries the multicast group on which the message was received. The least significant bit corresponds to group 1, and therefore the highest group that the field can represent is 32. Above that, the UB sanitizer flags the out-of-bounds shift attempts. Which bits end up being set in such case is implementation defined, but it's either going to be a wrong non-zero value, or zero, which is at least not misleading. Make the latter choice deterministic by always setting to 0 for higher-numbered multicast groups. To get information about membership in groups >= 32, userspace is expected to use nl_pktinfo control messages[0], which are enabled by NETLINK_PKTINFO socket option. [0] https://lwn.net/Articles/147608/ The way to trigger this issue is e.g. through monitoring the BRVLAN group: # bridge monitor vlan & # ip link add name br type bridge Which produces the following citation: UBSAN: shift-out-of-bounds in net/netlink/af_netlink.c:162:19 shift exponent 32 is too large for 32-bit type 'int' Fixes: f7fa9b10edbb ("[NETLINK]: Support dynamic number of multicast groups per netlink family") Signed-off-by: Petr Machata Reviewed-by: Ido Schimmel Link: https://lore.kernel.org/r/2bef6aabf201d1fc16cca139a744700cff9dcb04.1647527635.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/netlink/af_netlink.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 13d69cbd14c2..8aef475fef31 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -161,6 +161,8 @@ static const struct rhashtable_params netlink_rhashtable_params; static inline u32 netlink_group_mask(u32 group) { + if (group > 32) + return 0; return group ? 1 << (group - 1) : 0; } -- 2.34.1