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=-13.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 4FA5EC433E1 for ; Sun, 2 Aug 2020 19:50:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43C5820759 for ; Sun, 2 Aug 2020 19:50:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ODggDmsS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727019AbgHBTuw (ORCPT ); Sun, 2 Aug 2020 15:50:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726364AbgHBTuv (ORCPT ); Sun, 2 Aug 2020 15:50:51 -0400 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78A06C06174A; Sun, 2 Aug 2020 12:50:51 -0700 (PDT) Received: by mail-pf1-x444.google.com with SMTP id j20so17068948pfe.5; Sun, 02 Aug 2020 12:50:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=B9BYrY99T620aK2jc5HkCpNbc33t/1UkwxGWa0hFtbs=; b=ODggDmsS4CbzPlYSm6/dZcfz6K+93ERd+GcOsML7aNME26dExFXZziMERjT2KwMU+d 99jbl6tYo88EkBQV5YqzWL6QJKSjK7hMGenklAnk30W1yLci29kGEMhqfybzTL8cr6Vc ZoRAm7PCva0v0Q26qsIQBjYjoNhCI/ekKOoutnScumQnMwVKwz1hGJkO+M/PMvOoFg3h HLxwSShsOwQAYd55FOG93JUv3MRckVtXMlDw3e5rLCvCPKwlhe6CwlmOl2Bo0l6dDjBE QGH8eO2+FExYSRjf3mOhizKN2kRnRCzHhp8hRgyPSBH0Hxeoan4PsnnzIER9f3kCSS7X IiPg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=B9BYrY99T620aK2jc5HkCpNbc33t/1UkwxGWa0hFtbs=; b=bdl17I8My1SV7TrGwBlhOhcKoJmY1Yl+GNRanSr2JsIisr4Pm2Wnh1zw9ofNenml3h +QxYQB5GPMDzBJtir92xoUZnVK0YraBYps0eNIFOBRLiwOhIOAz252+U3zYExl9Wjne+ JndLbUMQC7C2NiU419F3GlrskLeI0bMi4aJ6T+1K2LBvJJnG02/TrpSZe0Zni/D8lTYW s/MRd/LXJCNQ3zq+RhPc53MY4EhY8bxyuntFUVMzffr2CKmDRulgaULkovQiwqERITlc vL1w9tKs7YIjd6q4Fa0HQDg+fgI9qPRHSnQVCXVYYwIMH5Yg4xBZgvmqlHP48CYnyWPZ 8CXA== X-Gm-Message-State: AOAM533pkdy9PkirRSYDBHRV0u6RLwm7Kq9M8GwV0P0zKBz213A6mdwB 5jFrmzQnae0R0c6U6Zafs54= X-Google-Smtp-Source: ABdhPJzQLiTKbO0Bx455zrbOP8QWJoW9XzcFMG00gL1yem0uoe1qn1Q0RHnZiUU+gv6jNk6d2VaVMw== X-Received: by 2002:a63:c509:: with SMTP id f9mr12096008pgd.144.1596397850910; Sun, 02 Aug 2020 12:50:50 -0700 (PDT) Received: from shane-XPS-13-9380.hsd1.ca.comcast.net ([2601:646:8880:9ae0:d9e7:bb5e:b692:1567]) by smtp.gmail.com with ESMTPSA id d5sm15189190pju.15.2020.08.02.12.50.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 02 Aug 2020 12:50:50 -0700 (PDT) From: Xie He To: "David S. Miller" , Jakub Kicinski , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-x25@vger.kernel.org Cc: Xie He , Willem de Bruijn , Brian Norris Subject: [net v3] drivers/net/wan/lapbether: Use needed_headroom instead of hard_header_len Date: Sun, 2 Aug 2020 12:50:46 -0700 Message-Id: <20200802195046.402539-1-xie.he.0141@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In net/packet/af_packet.c, the function packet_snd first reserves a headroom of length (dev->hard_header_len + dev->needed_headroom). Then if the socket is a SOCK_DGRAM socket, it calls dev_hard_header, which calls dev->header_ops->create, to create the link layer header. If the socket is a SOCK_RAW socket, it "un-reserves" a headroom of length (dev->hard_header_len), and assumes the user to provide the appropriate link layer header. So according to the logic of af_packet.c, dev->hard_header_len should be the length of the header that would be created by dev->header_ops->create. However, this driver doesn't provide dev->header_ops, so logically dev->hard_header_len should be 0. So we should use dev->needed_headroom instead of dev->hard_header_len to request necessary headroom to be allocated. This change fixes kernel panic when this driver is used with AF_PACKET SOCK_RAW sockets. Call stack when panic: [ 168.399197] skbuff: skb_under_panic: text:ffffffff819d95fb len:20 put:14 head:ffff8882704c0a00 data:ffff8882704c09fd tail:0x11 end:0xc0 dev:veth0 ... [ 168.399255] Call Trace: [ 168.399259] skb_push.cold+0x14/0x24 [ 168.399262] eth_header+0x2b/0xc0 [ 168.399267] lapbeth_data_transmit+0x9a/0xb0 [lapbether] [ 168.399275] lapb_data_transmit+0x22/0x2c [lapb] [ 168.399277] lapb_transmit_buffer+0x71/0xb0 [lapb] [ 168.399279] lapb_kick+0xe3/0x1c0 [lapb] [ 168.399281] lapb_data_request+0x76/0xc0 [lapb] [ 168.399283] lapbeth_xmit+0x56/0x90 [lapbether] [ 168.399286] dev_hard_start_xmit+0x91/0x1f0 [ 168.399289] ? irq_init_percpu_irqstack+0xc0/0x100 [ 168.399291] __dev_queue_xmit+0x721/0x8e0 [ 168.399295] ? packet_parse_headers.isra.0+0xd2/0x110 [ 168.399297] dev_queue_xmit+0x10/0x20 [ 168.399298] packet_sendmsg+0xbf0/0x19b0 ...... Additional change: When sending, check skb->len to ensure the 1-byte pseudo header is present before reading it. Cc: Willem de Bruijn Cc: Brian Norris Signed-off-by: Xie He --- Change from v2: Added skb->len check when sending. Change from v1: None --- drivers/net/wan/lapbether.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c index b2868433718f..8a3f7ba36f7e 100644 --- a/drivers/net/wan/lapbether.c +++ b/drivers/net/wan/lapbether.c @@ -157,6 +157,9 @@ static netdev_tx_t lapbeth_xmit(struct sk_buff *skb, if (!netif_running(dev)) goto drop; + if (skb->len < 1) + goto drop; + switch (skb->data[0]) { case X25_IFACE_DATA: break; @@ -305,6 +308,7 @@ static void lapbeth_setup(struct net_device *dev) dev->netdev_ops = &lapbeth_netdev_ops; dev->needs_free_netdev = true; dev->type = ARPHRD_X25; + dev->hard_header_len = 0; dev->mtu = 1000; dev->addr_len = 0; } @@ -331,7 +335,8 @@ static int lapbeth_new_device(struct net_device *dev) * then this driver prepends a length field of 2 bytes, * then the underlying Ethernet device prepends its own header. */ - ndev->hard_header_len = -1 + 3 + 2 + dev->hard_header_len; + ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len + + dev->needed_headroom; lapbeth = netdev_priv(ndev); lapbeth->axdev = ndev; -- 2.25.1