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 2368EC54EE9 for ; Tue, 13 Sep 2022 15:45:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231877AbiIMPpn (ORCPT ); Tue, 13 Sep 2022 11:45:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231886AbiIMPpH (ORCPT ); Tue, 13 Sep 2022 11:45:07 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 146D65F7F6; Tue, 13 Sep 2022 07:48:46 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 8CEBF614D1; Tue, 13 Sep 2022 14:25:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8DE03C433C1; Tue, 13 Sep 2022 14:25:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663079109; bh=XkQbDJaMEkaRdkohvyKxOTHcsS3Jp20F3IRQadi3+84=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a8OpAXWXCTLYCZL/LrbnHxDKrdyNjyDPsMio7ggFGrsbxSNElRsCedjniTS9qk15u oaydv2ROX/uN0CsqDzWIhLUJBPa79H2+QaBperm5EWcQxIc2DbAPyo7vcXrNcV5HLM 8lvQfnsCyOadc/Hf/19Kf9RR3DFHV0+t59/xPN7s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lucas Leong , David Lebrun , "David S. Miller" , Sasha Levin Subject: [PATCH 5.10 62/79] ipv6: sr: fix out-of-bounds read when setting HMAC data. Date: Tue, 13 Sep 2022 16:05:07 +0200 Message-Id: <20220913140353.206087559@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220913140350.291927556@linuxfoundation.org> References: <20220913140350.291927556@linuxfoundation.org> User-Agent: quilt/0.67 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: David Lebrun [ Upstream commit 84a53580c5d2138c7361c7c3eea5b31827e63b35 ] The SRv6 layer allows defining HMAC data that can later be used to sign IPv6 Segment Routing Headers. This configuration is realised via netlink through four attributes: SEG6_ATTR_HMACKEYID, SEG6_ATTR_SECRET, SEG6_ATTR_SECRETLEN and SEG6_ATTR_ALGID. Because the SECRETLEN attribute is decoupled from the actual length of the SECRET attribute, it is possible to provide invalid combinations (e.g., secret = "", secretlen = 64). This case is not checked in the code and with an appropriately crafted netlink message, an out-of-bounds read of up to 64 bytes (max secret length) can occur past the skb end pointer and into skb_shared_info: Breakpoint 1, seg6_genl_sethmac (skb=, info=) at net/ipv6/seg6.c:208 208 memcpy(hinfo->secret, secret, slen); (gdb) bt #0 seg6_genl_sethmac (skb=, info=) at net/ipv6/seg6.c:208 #1 0xffffffff81e012e9 in genl_family_rcv_msg_doit (skb=skb@entry=0xffff88800b1f9f00, nlh=nlh@entry=0xffff88800b1b7600, extack=extack@entry=0xffffc90000ba7af0, ops=ops@entry=0xffffc90000ba7a80, hdrlen=4, net=0xffffffff84237580 , family=, family=) at net/netlink/genetlink.c:731 #2 0xffffffff81e01435 in genl_family_rcv_msg (extack=0xffffc90000ba7af0, nlh=0xffff88800b1b7600, skb=0xffff88800b1f9f00, family=0xffffffff82fef6c0 ) at net/netlink/genetlink.c:775 #3 genl_rcv_msg (skb=0xffff88800b1f9f00, nlh=0xffff88800b1b7600, extack=0xffffc90000ba7af0) at net/netlink/genetlink.c:792 #4 0xffffffff81dfffc3 in netlink_rcv_skb (skb=skb@entry=0xffff88800b1f9f00, cb=cb@entry=0xffffffff81e01350 ) at net/netlink/af_netlink.c:2501 #5 0xffffffff81e00919 in genl_rcv (skb=0xffff88800b1f9f00) at net/netlink/genetlink.c:803 #6 0xffffffff81dff6ae in netlink_unicast_kernel (ssk=0xffff888010eec800, skb=0xffff88800b1f9f00, sk=0xffff888004aed000) at net/netlink/af_netlink.c:1319 #7 netlink_unicast (ssk=ssk@entry=0xffff888010eec800, skb=skb@entry=0xffff88800b1f9f00, portid=portid@entry=0, nonblock=) at net/netlink/af_netlink.c:1345 #8 0xffffffff81dff9a4 in netlink_sendmsg (sock=, msg=0xffffc90000ba7e48, len=) at net/netlink/af_netlink.c:1921 ... (gdb) p/x ((struct sk_buff *)0xffff88800b1f9f00)->head + ((struct sk_buff *)0xffff88800b1f9f00)->end $1 = 0xffff88800b1b76c0 (gdb) p/x secret $2 = 0xffff88800b1b76c0 (gdb) p slen $3 = 64 '@' The OOB data can then be read back from userspace by dumping HMAC state. This commit fixes this by ensuring SECRETLEN cannot exceed the actual length of SECRET. Reported-by: Lucas Leong Tested: verified that EINVAL is correctly returned when secretlen > len(secret) Fixes: 4f4853dc1c9c1 ("ipv6: sr: implement API to control SR HMAC structure") Signed-off-by: David Lebrun Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv6/seg6.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c index d2f8138e5a73a..2278c0234c497 100644 --- a/net/ipv6/seg6.c +++ b/net/ipv6/seg6.c @@ -135,6 +135,11 @@ static int seg6_genl_sethmac(struct sk_buff *skb, struct genl_info *info) goto out_unlock; } + if (slen > nla_len(info->attrs[SEG6_ATTR_SECRET])) { + err = -EINVAL; + goto out_unlock; + } + if (hinfo) { err = seg6_hmac_info_del(net, hmackeyid); if (err) -- 2.35.1