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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 8FBCBC433E0 for ; Tue, 23 Feb 2021 01:30:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38F8860233 for ; Tue, 23 Feb 2021 01:30:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230060AbhBWBa5 (ORCPT ); Mon, 22 Feb 2021 20:30:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:39246 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230042AbhBWBa5 (ORCPT ); Mon, 22 Feb 2021 20:30:57 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7DFFF64E57; Tue, 23 Feb 2021 01:30:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614043816; bh=ncie3eGoP1Lo7pENaLRqCW2fkUMl2yR3qc5u8v9f/Cs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MyaOfdQ9yb+Jt1rs6BqyaFO5YLrlUhDHHOh2P6qeIQvBeKoXJV6f/o5WInaM0gWds 567BIW+sx8ibyf8SpHpSMFPxwhfG9tUAFIwAJC0omA/3h+qtASKo4guFtMrr5QOG2O wTqnSPJ5TiwOfiTRz2a9quZsIasxGTyXiNfjzMyTpeGemqWvZAH26YoHbgp7wnnG81 FPqUI5oZUQKmcRF/2NqkbGNjb1WybkM8DtHTk7d6fReE0HIiGIpHULqejofiDpqn6f BJU1QTcKUCM5RKK5csIN8uc0xTYwrYy6zeS+lgNRFioqoePS5mLm143FDaZ/2FRMUs WyDxYAHySz5YA== Date: Mon, 22 Feb 2021 17:30:12 -0800 From: Jakub Kicinski To: Oleksij Rempel 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: <20210222173012.39e82e8d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: <20210222150251.12911-1-o.rempel@pengutronix.de> References: <20210222150251.12911-1-o.rempel@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-can@vger.kernel.org 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 */ ? > +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 > * @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? > + 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 tree > > ndev = dev_get_by_index(net, addr->can_ifindex); > if (!ndev) {