From patchwork Wed May 5 15:35:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 431522 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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS autolearn=ham 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 9B81BC43460 for ; Wed, 5 May 2021 15:36:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 746A6613C9 for ; Wed, 5 May 2021 15:36:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233545AbhEEPhP (ORCPT ); Wed, 5 May 2021 11:37:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:27589 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233525AbhEEPhM (ORCPT ); Wed, 5 May 2021 11:37:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1620228975; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hgkEObWrhPpU0VWlIFg59d/bFDsmQ4iUBVoNuyOzllY=; b=Ps+Uicae+ArtTTTBlmcnYvUqN8N0ZlmI1NlMSESMtaMlkGPK7J7bEOXr5pUBJiOLlChRDI tx6teUkNUC99AH2/NwPUykCh4JI6oLe7LsiWaV8uDgOqbkiY/z27mCZgMmeQW5kRYEpaer o5JhH99t3QozE0rA+mlRAky7XkErbRM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-104-QvKtzQ0dNSqwtQjUaT4kGA-1; Wed, 05 May 2021 11:36:13 -0400 X-MC-Unique: QvKtzQ0dNSqwtQjUaT4kGA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D0086107ACC7; Wed, 5 May 2021 15:36:11 +0000 (UTC) Received: from gerbillo.redhat.com (ovpn-113-175.ams2.redhat.com [10.36.113.175]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4A7635C1A3; Wed, 5 May 2021 15:36:10 +0000 (UTC) From: Paolo Abeni To: netdev@vger.kernel.org Cc: "David S. Miller" , Jakub Kicinski , Steffen Klassert , Willem de Bruijn , Miaohe Lin Subject: [PATCH net 2/4] udp: fix out-of-bound at segmentation time Date: Wed, 5 May 2021 17:35:02 +0200 Message-Id: <5e72b33838c6f19d770062e736f0517610ada4e7.1620223174.git.pabeni@redhat.com> In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In the following scenario: GRO -> SKB_GSO_FRAGLIST aggregation -> forward -> xmit over UDP tunnel -> segmentation __udp_gso_segment_list() will take place and later skb_udp_tunnel_segment() will try to make the segmented packets outer UDP header checksum via gso_make_checksum(). The latter expect valids SKB_GSO_CB(skb)->csum and SKB_GSO_CB(skb)->csum_start, but such fields are not initialized by __udp_gso_segment_list(). gso_make_checksum() will end-up using a negative offset and that will trigger the following splat: ================================================================== BUG: KASAN: slab-out-of-bounds in do_csum+0x3d8/0x400 Read of size 1 at addr ffff888113ab5880 by task napi/br_port-81/1105 CPU: 1 PID: 1105 Comm: napi/br_port-81 Not tainted 5.12.0-rc2.mptcp_autotune_ce84e1323bebe+ #268 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 Call Trace: dump_stack+0xfa/0x151 print_address_description.constprop.0+0x16/0xa0 __kasan_report.cold+0x37/0x80 kasan_report+0x3a/0x50 do_csum+0x3d8/0x400 csum_partial+0x21/0x30 __skb_udp_tunnel_segment+0xd79/0x1ae0 skb_udp_tunnel_segment+0x233/0x460 udp4_ufo_fragment+0x50d/0x720 inet_gso_segment+0x525/0x1120 skb_mac_gso_segment+0x278/0x570 __udp_gso_segment_list() already has all the relevant data handy, fix the issue traversing the segments list and updating the GSO CB, if this is a tunnel GSO packet. The issue is present since SKB_GSO_FRAGLIST introduction, but is observable only since commit 18f25dc39990 ("udp: skip L4 aggregation for UDP tunnel packets") Fixes: 18f25dc39990 ("udp: skip L4 aggregation for UDP tunnel packets") Signed-off-by: Paolo Abeni --- net/ipv4/udp_offload.c | 45 +++++++++++++++++++++++++++++------------- 1 file changed, 31 insertions(+), 14 deletions(-) diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 54e06b88af69..9f6022ba6bcd 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -214,8 +214,10 @@ static void __udpv4_gso_segment_csum(struct sk_buff *seg, *oldip = *newip; } -static struct sk_buff *__udpv4_gso_segment_list_csum(struct sk_buff *segs) +static void __udp_gso_segment_list_csum(struct sk_buff *segs, bool is_ipv6, + bool is_tunnel) { + bool update_csum = !is_ipv6; struct sk_buff *seg; struct udphdr *uh, *uh2; struct iphdr *iph, *iph2; @@ -224,31 +226,45 @@ static struct sk_buff *__udpv4_gso_segment_list_csum(struct sk_buff *segs) uh = udp_hdr(seg); iph = ip_hdr(seg); - if ((udp_hdr(seg)->dest == udp_hdr(seg->next)->dest) && + if (update_csum && (udp_hdr(seg)->dest == udp_hdr(seg->next)->dest) && (udp_hdr(seg)->source == udp_hdr(seg->next)->source) && (ip_hdr(seg)->daddr == ip_hdr(seg->next)->daddr) && (ip_hdr(seg)->saddr == ip_hdr(seg->next)->saddr)) - return segs; + update_csum = false; + + if (!update_csum && !is_tunnel) + return; + /* this skb is CHECKSUM_NONE, if it has also a tunnel header + * later __skb_udp_tunnel_segment() will try to make the + * outer header csum and will need valid csum* fields + */ + SKB_GSO_CB(seg)->csum = ~uh->check; + SKB_GSO_CB(seg)->csum_start = seg->transport_header; while ((seg = seg->next)) { uh2 = udp_hdr(seg); - iph2 = ip_hdr(seg); - - __udpv4_gso_segment_csum(seg, - &iph2->saddr, &iph->saddr, - &uh2->source, &uh->source); - __udpv4_gso_segment_csum(seg, - &iph2->daddr, &iph->daddr, - &uh2->dest, &uh->dest); - } + if (update_csum) { + iph2 = ip_hdr(seg); + + __udpv4_gso_segment_csum(seg, + &iph2->saddr, &iph->saddr, + &uh2->source, &uh->source); + __udpv4_gso_segment_csum(seg, + &iph2->daddr, &iph->daddr, + &uh2->dest, &uh->dest); + } - return segs; + SKB_GSO_CB(seg)->csum = ~uh2->check; + SKB_GSO_CB(seg)->csum_start = seg->transport_header; + } } static struct sk_buff *__udp_gso_segment_list(struct sk_buff *skb, netdev_features_t features, bool is_ipv6) { + bool is_tunnel = !!(skb_shinfo(skb)->gso_type & + (SKB_GSO_UDP_TUNNEL | SKB_GSO_UDP_TUNNEL_CSUM)); unsigned int mss = skb_shinfo(skb)->gso_size; skb = skb_segment_list(skb, features, skb_mac_header_len(skb)); @@ -257,7 +273,8 @@ static struct sk_buff *__udp_gso_segment_list(struct sk_buff *skb, udp_hdr(skb)->len = htons(sizeof(struct udphdr) + mss); - return is_ipv6 ? skb : __udpv4_gso_segment_list_csum(skb); + __udp_gso_segment_list_csum(skb, is_ipv6, is_tunnel); + return skb; } struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,