From patchwork Wed Jan 20 10:24:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincent MAILHOL X-Patchwork-Id: 367656 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, 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 B8DFFC4360C for ; Wed, 20 Jan 2021 11:21:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77D1C22AAA for ; Wed, 20 Jan 2021 11:21:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389045AbhATLP7 (ORCPT ); Wed, 20 Jan 2021 06:15:59 -0500 Received: from smtp13.smtpout.orange.fr ([80.12.242.135]:44217 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731181AbhATK2F (ORCPT ); Wed, 20 Jan 2021 05:28:05 -0500 Received: from localhost.localdomain ([153.202.107.157]) by mwinf5d76 with ME id JyS92400F3PnFJp03ySFsm; Wed, 20 Jan 2021 11:26:20 +0100 X-ME-Helo: localhost.localdomain X-ME-Auth: bWFpbGhvbC52aW5jZW50QHdhbmFkb28uZnI= X-ME-Date: Wed, 20 Jan 2021 11:26:20 +0100 X-ME-IP: 153.202.107.157 From: Vincent Mailhol To: Marc Kleine-Budde , Oliver Hartkopp , linux-can@vger.kernel.org Cc: netdev@vger.kernel.org, Wolfgang Grandegger , Stephane Grosjean , Loris Fauster , Alejandro Concepcion Rodriguez , Dan Carpenter , Vincent Mailhol Subject: [PATCH v3 2/3] can: vxcan: vxcan_xmit: fix use after free bug Date: Wed, 20 Jan 2021 19:24:42 +0900 Message-Id: <20210120102443.198143-3-mailhol.vincent@wanadoo.fr> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210120102443.198143-1-mailhol.vincent@wanadoo.fr> References: <20210120102443.198143-1-mailhol.vincent@wanadoo.fr> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org After calling netif_rx_ni(skb), dereferencing skb is unsafe. Especially, the canfd_frame cfd which aliases skb memory is accessed after the netif_rx_ni(). Fixes: a8f820a380a2 ("can: add Virtual CAN Tunnel driver (vxcan)") Signed-off-by: Vincent Mailhol --- drivers/net/can/vxcan.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/can/vxcan.c b/drivers/net/can/vxcan.c index fa47bab510bb..f9a524c5f6d6 100644 --- a/drivers/net/can/vxcan.c +++ b/drivers/net/can/vxcan.c @@ -39,6 +39,7 @@ static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev) struct net_device *peer; struct canfd_frame *cfd = (struct canfd_frame *)skb->data; struct net_device_stats *peerstats, *srcstats = &dev->stats; + u8 len; if (can_dropped_invalid_skb(dev, skb)) return NETDEV_TX_OK; @@ -61,12 +62,13 @@ static netdev_tx_t vxcan_xmit(struct sk_buff *skb, struct net_device *dev) skb->dev = peer; skb->ip_summed = CHECKSUM_UNNECESSARY; + len = cfd->len; if (netif_rx_ni(skb) == NET_RX_SUCCESS) { srcstats->tx_packets++; - srcstats->tx_bytes += cfd->len; + srcstats->tx_bytes += len; peerstats = &peer->stats; peerstats->rx_packets++; - peerstats->rx_bytes += cfd->len; + peerstats->rx_bytes += len; } out_unlock: