From patchwork Fri May 8 12:34:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 226236 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, USER_AGENT_GIT 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 4A801C47247 for ; Fri, 8 May 2020 12:48:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D3E321473 for ; Fri, 8 May 2020 12:48:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588942132; bh=gI8pMIvh5jN8BWPY6uAaQ6DrV5F1LYg7eIi5Fw+94Pk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cHh3b4tEX4ge96N27kh5StQNR03oc9bw/JGKkGhd11xNz7GIfBPRU1wPSnHGr8JmI nObQ7N4kGhWA791pkuG4zozZZ81C5LLbfoxEzGJN2xlxkgaHm7FmpUQX+ujMYdJsIi SviRDbytH8sPCqwRoJXFPsOJaenelG3g10tHOGpE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729697AbgEHMsu (ORCPT ); Fri, 8 May 2020 08:48:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:53260 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729692AbgEHMst (ORCPT ); Fri, 8 May 2020 08:48:49 -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 D09C821473; Fri, 8 May 2020 12:48:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588942128; bh=gI8pMIvh5jN8BWPY6uAaQ6DrV5F1LYg7eIi5Fw+94Pk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F5/LECh5Vlxx9uqDnllvOW04/bJ/esz4JSHlS6xB9HbckMJdGPTH8SqP1kKW2jybk 77Yc5avwbzq9XlG/+gjOCNjg9TjMN8sqUs/Tj/m2K6dhzwbeannuwPTjj36BLapeAu l72EoGslCJVZ3BaG8B4EcAQOkWHLqxaqTMZeIfTY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shmulik Ladkani , Pravin Shelar , "David S. Miller" Subject: [PATCH 4.4 307/312] net: skbuff: Remove errornous length validation in skb_vlan_pop() Date: Fri, 8 May 2020 14:34:58 +0200 Message-Id: <20200508123146.094231743@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200508123124.574959822@linuxfoundation.org> References: <20200508123124.574959822@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Shmulik Ladkani commit 636c2628086e40c86dac7ddc84a1c4b4fcccc6e3 upstream. In 93515d53b1 "net: move vlan pop/push functions into common code" skb_vlan_pop was moved from its private location in openvswitch to skbuff common code. In case skb has non hw-accel vlan tag, the original 'pop_vlan()' assured that skb->len is sufficient (if skb->len < VLAN_ETH_HLEN then pop was considered a no-op). This validation was moved as is into the new common 'skb_vlan_pop'. Alas, in its original location (openvswitch), there was a guarantee that 'data' points to the mac_header, therefore the 'skb->len < VLAN_ETH_HLEN' condition made sense. However there's no such guarantee in the generic 'skb_vlan_pop'. For short packets received in rx path going through 'skb_vlan_pop', this causes 'skb_vlan_pop' to fail pop-ing a valid vlan hdr (in the non hw-accel case) or to fail moving next tag into hw-accel tag. Remove the 'skb->len < VLAN_ETH_HLEN' condition entirely: It is superfluous since inner '__skb_vlan_pop' already verifies there are VLAN_ETH_HLEN writable bytes at the mac_header. Note this presents a slight change to skb_vlan_pop() users: In case total length is smaller than VLAN_ETH_HLEN, skb_vlan_pop() now returns an error, as opposed to previous "no-op" behavior. Existing callers (e.g. tc act vlan, ovs) usually drop the packet if 'skb_vlan_pop' fails. Fixes: 93515d53b1 ("net: move vlan pop/push functions into common code") Signed-off-by: Shmulik Ladkani Cc: Pravin Shelar Reviewed-by: Pravin B Shelar Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/skbuff.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4451,9 +4451,8 @@ int skb_vlan_pop(struct sk_buff *skb) if (likely(skb_vlan_tag_present(skb))) { skb->vlan_tci = 0; } else { - if (unlikely((skb->protocol != htons(ETH_P_8021Q) && - skb->protocol != htons(ETH_P_8021AD)) || - skb->len < VLAN_ETH_HLEN)) + if (unlikely(skb->protocol != htons(ETH_P_8021Q) && + skb->protocol != htons(ETH_P_8021AD))) return 0; err = __skb_vlan_pop(skb, &vlan_tci); @@ -4461,9 +4460,8 @@ int skb_vlan_pop(struct sk_buff *skb) return err; } /* move next vlan tag to hw accel tag */ - if (likely((skb->protocol != htons(ETH_P_8021Q) && - skb->protocol != htons(ETH_P_8021AD)) || - skb->len < VLAN_ETH_HLEN)) + if (likely(skb->protocol != htons(ETH_P_8021Q) && + skb->protocol != htons(ETH_P_8021AD))) return 0; vlan_proto = skb->protocol;