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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 25A4BC433DB for ; Tue, 23 Feb 2021 06:52:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4E0C60C41 for ; Tue, 23 Feb 2021 06:52:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231582AbhBWGwk (ORCPT ); Tue, 23 Feb 2021 01:52:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231484AbhBWGwj (ORCPT ); Tue, 23 Feb 2021 01:52:39 -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 7B3E7C06174A for ; Mon, 22 Feb 2021 22:51:58 -0800 (PST) Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lERXx-0002JM-FV; Tue, 23 Feb 2021 07:51:49 +0100 Received: from ore by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1lERXw-00045Y-Ga; Tue, 23 Feb 2021 07:51:48 +0100 Date: Tue, 23 Feb 2021 07:51:48 +0100 From: Oleksij Rempel To: Jakub Kicinski Cc: mkl@pengutronix.de, "David S. Miller" , Oliver Hartkopp , Robin van der Gracht , syzbot+5138c4dd15a0401bec7b@syzkaller.appspotmail.com, kernel@pengutronix.de, linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net v3] net: introduce CAN specific pointer in the struct net_device Message-ID: <20210223065148.kof3e4ktxawrgykn@pengutronix.de> References: <20210222150251.12911-1-o.rempel@pengutronix.de> <20210222173012.39e82e8d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210222173012.39e82e8d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 06:57:04 up 82 days, 20:03, 38 users, load average: 0.01, 0.04, 0.04 User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ore@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 Hi Jakub, On Mon, Feb 22, 2021 at 05:30:12PM -0800, Jakub Kicinski wrote: > On Mon, 22 Feb 2021 16:02:51 +0100 Oleksij Rempel wrote: > > Since 20dd3850bcf8 ("can: Speed up CAN frame receiption by using > > ml_priv") the CAN framework uses per device specific data in the AF_CAN > > protocol. For this purpose the struct net_device->ml_priv is used. Later > > the ml_priv usage in CAN was extended for other users, one of them being > > CAN_J1939. > > > > Later in the kernel ml_priv was converted to an union, used by other > > drivers. E.g. the tun driver started storing it's stats pointer. > > > > Since tun devices can claim to be a CAN device, CAN specific protocols > > will wrongly interpret this pointer, which will cause system crashes. > > Mostly this issue is visible in the CAN_J1939 stack. > > > > To fix this issue, we request a dedicated CAN pointer within the > > net_device struct. > > > > Reported-by: syzbot+5138c4dd15a0401bec7b@syzkaller.appspotmail.com > > Fixes: 20dd3850bcf8 ("can: Speed up CAN frame receiption by using ml_priv") > > Fixes: ffd956eef69b ("can: introduce CAN midlayer private and allocate it automatically") > > Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol") > > Fixes: 497a5757ce4e ("tun: switch to net core provided statistics counters") > > Signed-off-by: Oleksij Rempel > > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > > index ddf4cfc12615..6e25c6f0f190 100644 > > --- a/include/linux/netdevice.h > > +++ b/include/linux/netdevice.h > > @@ -1584,6 +1584,16 @@ enum netdev_priv_flags { > > #define IFF_L3MDEV_RX_HANDLER IFF_L3MDEV_RX_HANDLER > > #define IFF_LIVE_RENAME_OK IFF_LIVE_RENAME_OK > > > > +/** > > + * enum netdev_ml_priv_type - &struct net_device ml_priv_type > > + * > > + * This enum specifies the type of the struct net_device::ml_priv pointer. > > + */ > > kdoc (scripts/kernel-doc -none include/linux/netdevice.h) is not happy > about the fact enum values are not defined. Perhaps they will be > sufficiently self-explanatory to not bother documenting? > > Maybe just: > > /* Specifies the type of the struct net_device::ml_priv pointer */ > > ? sounds good, done. > > +enum netdev_ml_priv_type { > > + ML_PRIV_NONE, > > + ML_PRIV_CAN, > > +}; > > + > > /** > > * struct net_device - The DEVICE structure. > > * > > @@ -1779,6 +1789,7 @@ enum netdev_priv_flags { > > * @nd_net: Network namespace this network device is inside > > * > > * @ml_priv: Mid-layer private > > + @ml_priv_type: Mid-layer private type > > missing '*' at the start of the line done > > * @lstats: Loopback statistics > > * @tstats: Tunnel statistics > > * @dstats: Dummy statistics > > @@ -2094,8 +2105,10 @@ struct net_device { > > possible_net_t nd_net; > > > > /* mid-layer private */ > > + void *ml_priv; > > + enum netdev_ml_priv_type ml_priv_type; > > + > > union { > > - void *ml_priv; > > struct pcpu_lstats __percpu *lstats; > > struct pcpu_sw_netstats __percpu *tstats; > > struct pcpu_dstats __percpu *dstats; > > @@ -2286,6 +2299,29 @@ static inline void netdev_reset_rx_headroom(struct net_device *dev) > > netdev_set_rx_headroom(dev, -1); > > } > > > > +static inline void *netdev_get_ml_priv(struct net_device *dev, > > + enum netdev_ml_priv_type type) > > +{ > > + if (dev->ml_priv_type != type) > > + return NULL; > > + > > + return dev->ml_priv; > > +} > > + > > +static inline void netdev_set_ml_priv(struct net_device *dev, > > + void *ml_priv, > > + enum netdev_ml_priv_type type) > > +{ > > + WARN_ONCE(dev->ml_priv_type && dev->ml_priv_type != type, > > + "Overwriting already set ml_priv_type (%u) with different ml_priv_type (%u)!\n", > > + dev->ml_priv_type, type); > > + WARN_ONCE(!dev->ml_priv_type && dev->ml_priv, > > + "Overwriting already set ml_priv and ml_priv_type is ML_PRIV_NONE!\n"); > > nit: do we need the _ONCE() this helper should be used on control path > and relatively rarely, no? I have no strong opinion right now. Changed to WARN() > > + dev->ml_priv = ml_priv; > > + dev->ml_priv_type = type; > > +} > > + > > /* > > * Net namespace inlines > > */ > > > @@ -454,6 +455,7 @@ static int j1939_sk_bind(struct socket *sock, struct sockaddr *uaddr, int len) > > j1939_local_ecu_put(priv, jsk->addr.src_name, jsk->addr.sa); > > } else { > > struct net_device *ndev; > > + struct can_ml_priv *can_ml; > > nit: rev xmas treei done > > > > > ndev = dev_get_by_index(net, addr->can_ifindex); > > if (!ndev) { > Thank you, Regards, Oleksij -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |