From patchwork Tue Nov 3 21:39:05 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anant Thazhemadam X-Patchwork-Id: 1393455 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=uBcqtXxC; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4CQjqv2wrKz9sRK for ; Wed, 4 Nov 2020 08:40:11 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732076AbgKCVkK (ORCPT ); Tue, 3 Nov 2020 16:40:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731573AbgKCVkD (ORCPT ); Tue, 3 Nov 2020 16:40:03 -0500 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 996D7C0613D1; Tue, 3 Nov 2020 13:40:01 -0800 (PST) Received: by mail-pf1-x441.google.com with SMTP id 13so15467038pfy.4; Tue, 03 Nov 2020 13:40:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=LYxyrhJUyD7xUDhPMGT9KbQkgLtBSXjotD//z5c9IGM=; b=uBcqtXxCIT7OQTiJdT+Qnn+S0FnPXZBeM86TpyoW967BncdTfodSmN8/R+yRaV1MJQ PDw1MVYyBj2oyt+NREUIyk6viRXgbJqLHlw2l10HkuyyplZ+5K1VVP6ObwjesMPZjMTN wYEIXqB6tk0TAJqiI6in56jENXYlR8fBJkitzcc0Fcv2uTHwQQwvNXm9/AMm9wbNJ8ZJ DbWRyih0sWmnJDfAllXmXM1YOJmiMzm9oqcr2CXQW2ujcrARs/xjkH9KUsotrc1QmgAd GPi195xiIdqJVS22MVHxmvwK2KSeT/nq8gHxkM1uMDgMGrsWn5tMxUG+t8JPnJfRX0Vy YzGw== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=LYxyrhJUyD7xUDhPMGT9KbQkgLtBSXjotD//z5c9IGM=; b=V9oGW2ZyErXifScT+kVFsgFcTFZ6i3w4hwQplFmwtH5x4OZfiVHdLVo4iycwdPmpbb J9I9R8ZUGbNz8sHim+PoRhFVTGM1odmAVUpF1ZL+oiPd4UClxRTCAw6qAVXRmYgcVkpp WW0U0a/lT9It0GkUGcS7caNhp8EJX485gW41JOxStcepiyllIYIyTYrIcBUrGbFph7eC U44DXGKV2jJAgQgqOiRzk89c4fA4OGEuNyn7g22ttnH6peVreLwNFBEY2XRu7UoWcWKm 0atsPoAvZhxKxhMNa3fphNP0EEZPnUHb/mDfXWWo7cu9rwKMK/RSsrXVFMEltsc8UFUR VqOg== X-Gm-Message-State: AOAM531DD7ymDJNShCMZ+dTFRMoZKow/tWjI9VYdjITMpo3pIT2N5qqN M4Xk6S6f6bJKkfP/4wXljhydGIDias7sha1Hc/0= X-Google-Smtp-Source: ABdhPJxGpC6zBdyx3WueMwpRhFVGrjpu+F+vENteUwE9jvq/wTmHenoZXXtA4WUWxTPWpLBili+/HA== X-Received: by 2002:a17:90a:160f:: with SMTP id n15mr1193792pja.75.1604439596052; Tue, 03 Nov 2020 13:39:56 -0800 (PST) Received: from localhost.localdomain ([49.207.221.93]) by smtp.gmail.com with ESMTPSA id 15sm16420108pgs.52.2020.11.03.13.39.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Nov 2020 13:39:55 -0800 (PST) From: Anant Thazhemadam To: socketcan@hartkopp.net, mkl@pengutronix.de, davem@davemloft.net, kuba@kernel.org Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Anant Thazhemadam , syzbot+9bcb0c9409066696d3aa@syzkaller.appspotmail.com Subject: [PATCH 1/2] can: af_can: prevent potential access of uninitialized member in can_rcv() Date: Wed, 4 Nov 2020 03:09:05 +0530 Message-Id: <20201103213906.24219-2-anant.thazhemadam@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201103213906.24219-1-anant.thazhemadam@gmail.com> References: <20201103213906.24219-1-anant.thazhemadam@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In can_rcv(), cfd->len is uninitialized when skb->len = 0, and this uninitialized cfd->len is accessed nonetheless by pr_warn_once(). Fix this uninitialized variable access by checking cfd->len's validity condition (cfd->len > CAN_MAX_DLEN) separately after the skb->len's condition is checked, and appropriately modify the log messages that are generated as well. In case either of the required conditions fail, the skb is freed and NET_RX_DROP is returned, same as before. Fixes: 8cb68751c115 ("can: af_can: can_rcv(): replace WARN_ONCE by pr_warn_once") Reported-by: syzbot+9bcb0c9409066696d3aa@syzkaller.appspotmail.com Tested-by: Anant Thazhemadam Signed-off-by: Anant Thazhemadam --- net/can/af_can.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/net/can/af_can.c b/net/can/af_can.c index ea29a6d97ef5..8ea01524f062 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -677,16 +677,25 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev, { struct canfd_frame *cfd = (struct canfd_frame *)skb->data; - if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU || - cfd->len > CAN_MAX_DLEN)) { - pr_warn_once("PF_CAN: dropped non conform CAN skbuf: dev type %d, len %d, datalen %d\n", + if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU)) { + pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n", + dev->type, skb->len); + goto free_skb; + } + + /* This check is made separately since cfd->len would be uninitialized if skb->len = 0. */ + if (unlikely(cfd->len > CAN_MAX_DLEN)) { + pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d, datalen %d\n", dev->type, skb->len, cfd->len); - kfree_skb(skb); - return NET_RX_DROP; + goto free_skb; } can_receive(skb, dev); return NET_RX_SUCCESS; + +free_skb: + kfree_skb(skb); + return NET_RX_DROP; } static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,