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=-7.0 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 E0B1AC282C3 for ; Thu, 24 Jan 2019 17:26:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF8122184C for ; Thu, 24 Jan 2019 17:26:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728986AbfAXR0A (ORCPT ); Thu, 24 Jan 2019 12:26:00 -0500 Received: from shiva144.upmc.fr ([134.157.0.144]:47328 "EHLO shiva144.upmc.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727765AbfAXR0A (ORCPT ); Thu, 24 Jan 2019 12:26:00 -0500 Received: from shiva144.upmc.fr (localhost [127.0.0.1]) by shiva144.upmc.fr (Postfix) with ESMTP id 6EFB061AB7; Thu, 24 Jan 2019 18:25:57 +0100 (CET) Received: from courriel.upmc.fr (courriel5.reseau.jussieu.fr [134.157.0.196]) by shiva144.upmc.fr (Postfix) with ESMTP id 603D76112D; Thu, 24 Jan 2019 18:25:57 +0100 (CET) X-CIds: courriel5 Received: from [44.168.19.30] (lfbn-1-499-146.w86-245.abo.wanadoo.fr [86.245.202.146]) (authentified, mech=PLAIN) by courriel.upmc.fr (8.14.5/jtpda-5.5pre1) with ESMTP id x0OHPtvH062813 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO) ; Thu, 24 Jan 2019 18:25:56 +0100 (CET) (envelope-from f6bvp@free.fr) Subject: Re: [PATCH] NET:AX25:ROSE NULL ax25_cb kernel panic To: linux-hams Cc: Ralf Baechle , Dmitry Vyukov , David Miller , Linux Netdev List , n1uro@n1uro.ampr.org, f6bvp , Dmitry Vyukov References: <57ADC4F4.6080707@free.fr> <19a0a879-8a8d-4c84-5de9-5ce222377fcb@free.fr> From: Bernard Pidoux Message-ID: Date: Thu, 24 Jan 2019 18:30:24 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <19a0a879-8a8d-4c84-5de9-5ce222377fcb@free.fr> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: fr X-Virus-Scanned: ClamAV using ClamSMTP Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > [PATCH] [ROSE] NULL ax25_cb kernel panic > > When an internally generated frame is handled by rose_xmit(), > rose_route_frame() is called: > > if (!rose_route_frame(skb, NULL)) { > dev_kfree_skb(skb); > stats->tx_errors++; > return NETDEV_TX_OK; > } > > We have the same code sequence in Net/Rom where an internally generated > frame is handled by nr_xmit() calling nr_route_frame(skb, NULL). > However, in this function NULL argument is tested while it is not in > rose_route_frame(). > Then kernel panic occurs later on when calling ax25cmp() with a NULL > ax25_cb argument as reported many times and recently with syzbot. > > We need to test if ax25 is NULL before using it. > > Here is the patch: > > diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c > index 77e9f85a2c92..7f075255a372 100644 > --- a/net/rose/rose_route.c > +++ b/net/rose/rose_route.c > @@ -850,6 +850,7 @@ void rose_link_device_down(struct net_device *dev) > > /* > * Route a frame to an appropriate AX.25 connection. > + * a NULL ax25_cb indicates an internally generated frame. > */ > int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25) > { > @@ -867,6 +868,10 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb > *ax25) > > if (skb->len < ROSE_MIN_LEN) > return res; > + > + if (!ax25) > + return rose_loopback_queue(skb, NULL); > + > frametype = skb->data[2]; > lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF); > if (frametype == ROSE_CALL_REQUEST && > Reported-by:syzbot+1a2c456a1ea08fa5b5f7@syzkaller.appspotmail.com > Signed-off-by: Bernard Pidoux, f6bvp