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 2D454C433EF for ; Mon, 18 Apr 2022 13:46:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244285AbiDRNrc (ORCPT ); Mon, 18 Apr 2022 09:47:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55972 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243810AbiDRN3H (ORCPT ); Mon, 18 Apr 2022 09:29:07 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32AB72183; Mon, 18 Apr 2022 05:53:53 -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 C8601B80E44; Mon, 18 Apr 2022 12:53:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 22286C385A7; Mon, 18 Apr 2022 12:53:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650286430; bh=imPm8s3163js/UbzvT+fhP1EWKFf3vbLroPYzRpbxfQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ly8JZqrQVoIFgcHyNmbzX8OxLvJegTdCw3AX5AIa67qacl7B/y+MtqMLobP8SpLsj u7H+9asZuzaCppIOnQC1idUKfjBNeZL+B0NsyNAwE0uoQg4duzIHiFbg+oTKZb7abv bLzIeRLDWhxUlr2InY2yP58NHwqEDFXDMCfucjok= 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 4.14 125/284] af_netlink: Fix shift out of bounds in group mask calculation Date: Mon, 18 Apr 2022 14:11:46 +0200 Message-Id: <20220418121214.755164993@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121210.689577360@linuxfoundation.org> References: <20220418121210.689577360@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: linux-kernel@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 0563b4d34eae..24e8ac2b724e 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -154,6 +154,8 @@ 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