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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4672DC3A5A8 for ; Wed, 4 Sep 2019 18:17:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22F5B206B8 for ; Wed, 4 Sep 2019 18:17:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567621058; bh=9j13SR6PFoGHS9DU6kXVZT3HtgNT+HZ/YvMRajqX1co=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Wd1U2NxTDEsI+o4yKs91HmtyI1iDydi1IZ29jqNSJjJeAnRJQFTNTlt6ENgeFLvFX 9cgYYptHVjxV4+yXJTg/biDA8G2C90GkvTxMsRLkfc7SFXxoI5/2Syp7toiGan0UPy URg6JSF8a7nPFeMhFOBYcUDJJMp3GQMUNyVCI5yk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389620AbfIDSMm (ORCPT ); Wed, 4 Sep 2019 14:12:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:57190 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733228AbfIDSMl (ORCPT ); Wed, 4 Sep 2019 14:12:41 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5B778206BA; Wed, 4 Sep 2019 18:12:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567620760; bh=9j13SR6PFoGHS9DU6kXVZT3HtgNT+HZ/YvMRajqX1co=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S/aFSJHOxyK+rNYtQX7lDG4CCSKzHaaynUVJW/elX4v25VM5r5aiLHZBMx1Yu6hC6 /1nY9zSOf771JrVl4YO2jt4efcVGnhqEMVfF5jNf4uKNs9Wvm/OBMM2GZt+sVqesv2 wchixQAJNL1p/C4dfw/omwcI8W1ZkbTy3VRN/s6M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hangbin Liu , Jonathan Lemon , "David S. Miller" Subject: [PATCH 5.2 058/143] xfrm/xfrm_policy: fix dst dev null pointer dereference in collect_md mode Date: Wed, 4 Sep 2019 19:53:21 +0200 Message-Id: <20190904175316.343523033@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190904175314.206239922@linuxfoundation.org> References: <20190904175314.206239922@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hangbin Liu [ Upstream commit c3b4c3a47e05d5fecf7354d75824a9d1b37f3e84 ] In decode_session{4,6} there is a possibility that the skb dst dev is NULL, e,g, with tunnel collect_md mode, which will cause kernel crash. Here is what the code path looks like, for GRE: - ip6gre_tunnel_xmit - ip6gre_xmit_ipv6 - __gre6_xmit - ip6_tnl_xmit - if skb->len - t->tun_hlen - eth_hlen > mtu; return -EMSGSIZE - icmpv6_send - icmpv6_route_lookup - xfrm_decode_session_reverse - decode_session4 - oif = skb_dst(skb)->dev->ifindex; <-- here - decode_session6 - oif = skb_dst(skb)->dev->ifindex; <-- here The reason is __metadata_dst_init() init dst->dev to NULL by default. We could not fix it in __metadata_dst_init() as there is no dev supplied. On the other hand, the skb_dst(skb)->dev is actually not needed as we called decode_session{4,6} via xfrm_decode_session_reverse(), so oif is not used by: fl4->flowi4_oif = reverse ? skb->skb_iif : oif; So make a dst dev check here should be clean and safe. v4: No changes. v3: No changes. v2: fix the issue in decode_session{4,6} instead of updating shared dst dev in {ip_md, ip6}_tunnel_xmit. Fixes: 8d79266bc48c ("ip6_tunnel: add collect_md mode to IPv6 tunnels") Signed-off-by: Hangbin Liu Tested-by: Jonathan Lemon Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/xfrm/xfrm_policy.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -3272,7 +3272,7 @@ decode_session4(struct sk_buff *skb, str struct flowi4 *fl4 = &fl->u.ip4; int oif = 0; - if (skb_dst(skb)) + if (skb_dst(skb) && skb_dst(skb)->dev) oif = skb_dst(skb)->dev->ifindex; memset(fl4, 0, sizeof(struct flowi4)); @@ -3390,7 +3390,7 @@ decode_session6(struct sk_buff *skb, str nexthdr = nh[nhoff]; - if (skb_dst(skb)) + if (skb_dst(skb) && skb_dst(skb)->dev) oif = skb_dst(skb)->dev->ifindex; memset(fl6, 0, sizeof(struct flowi6));