From patchwork Sat Nov 14 17:33:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Kleine-Budde X-Patchwork-Id: 11905741 X-Patchwork-Delegate: kuba@kernel.org 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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 0FE3DC5519F for ; Sat, 14 Nov 2020 17:35:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E15EF2222C for ; Sat, 14 Nov 2020 17:35:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726203AbgKNRef (ORCPT ); Sat, 14 Nov 2020 12:34:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55992 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726175AbgKNRee (ORCPT ); Sat, 14 Nov 2020 12:34:34 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01E72C0613D2 for ; Sat, 14 Nov 2020 09:34:33 -0800 (PST) Received: from heimdall.vpn.pengutronix.de ([2001:67c:670:205:1d::14] helo=blackshift.org) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1kdzRX-0000mY-RY; Sat, 14 Nov 2020 18:34:31 +0100 From: Marc Kleine-Budde To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org, kernel@pengutronix.de, Anant Thazhemadam , syzbot+9bcb0c9409066696d3aa@syzkaller.appspotmail.com, Marc Kleine-Budde Subject: [net 02/15] can: af_can: prevent potential access of uninitialized member in canfd_rcv() Date: Sat, 14 Nov 2020 18:33:46 +0100 Message-Id: <20201114173358.2058600-3-mkl@pengutronix.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201114173358.2058600-1-mkl@pengutronix.de> References: <20201114173358.2058600-1-mkl@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:205:1d::14 X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: netdev@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Anant Thazhemadam In canfd_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 > CANFD_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: d4689846881d ("can: af_can: canfd_rcv(): replace WARN_ONCE by pr_warn_once") Reported-by: syzbot+9bcb0c9409066696d3aa@syzkaller.appspotmail.com Tested-by: Anant Thazhemadam Signed-off-by: Anant Thazhemadam Link: https://lore.kernel.org/r/20201103213906.24219-3-anant.thazhemadam@gmail.com Signed-off-by: Marc Kleine-Budde --- 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 e8d4e3ef5322..5d124c155904 100644 --- a/net/can/af_can.c +++ b/net/can/af_can.c @@ -703,16 +703,25 @@ static int canfd_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 != CANFD_MTU || - cfd->len > CANFD_MAX_DLEN)) { - pr_warn_once("PF_CAN: dropped non conform CAN FD skbuf: dev type %d, len %d, datalen %d\n", + if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU)) { + pr_warn_once("PF_CAN: dropped non conform CAN FD 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 > CANFD_MAX_DLEN)) { + pr_warn_once("PF_CAN: dropped non conform CAN FD 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; } /* af_can protocol functions */