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=-16.8 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=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 C069DC4338F for ; Fri, 20 Aug 2021 09:03:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A2CF760F25 for ; Fri, 20 Aug 2021 09:03:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234963AbhHTJEU (ORCPT ); Fri, 20 Aug 2021 05:04:20 -0400 Received: from smtp11.smtpout.orange.fr ([80.12.242.133]:40667 "EHLO smtp.smtpout.orange.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234684AbhHTJET (ORCPT ); Fri, 20 Aug 2021 05:04:19 -0400 Received: from tomoyo.flets-east.jp ([114.149.34.46]) by mwinf5d89 with ME id jl3S250090zjR6y03l3dMz; Fri, 20 Aug 2021 11:03:39 +0200 X-ME-Helo: tomoyo.flets-east.jp X-ME-Auth: bWFpbGhvbC52aW5jZW50QHdhbmFkb28uZnI= X-ME-Date: Fri, 20 Aug 2021 11:03:39 +0200 X-ME-IP: 114.149.34.46 From: Vincent Mailhol To: Marc Kleine-Budde , linux-can@vger.kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Vincent Mailhol Subject: [PATCH] can: netlink: prevent incoherent can configuration in case of early return Date: Fri, 20 Aug 2021 18:03:13 +0900 Message-Id: <20210820090313.299483-1-mailhol.vincent@wanadoo.fr> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org struct can_priv has a set of flags (can_priv::ctrlmode) which are correlated with the other field of the structure. In can_changelink(), those flags are set first and copied to can_priv. If the function has to return early, for example due to an out of range value provided by the user, then the global configuration might become incoherent. Example: the user provides an out of range dbitrate (e.g. 20 Mbps). The command fails (-EINVAL), however the FD flag was already set resulting in a configuration where FD is on but the databittiming parameters are empty. Illustration of above example: | $ ip link set can0 type can bitrate 500000 dbitrate 20000000 fd on | RTNETLINK answers: Invalid argument | $ ip --details link show can0 | 1: can0: mtu 72 qdisc noop state DOWN mode DEFAULT group default qlen 10 | link/can promiscuity 0 minmtu 0 maxmtu 0 | can state STOPPED restart-ms 0 ^^ FD flag is set without any of the databittiming parameters... | bitrate 500000 sample-point 0.875 | tq 12 prop-seg 69 phase-seg1 70 phase-seg2 20 sjw 1 | ES582.1/ES584.1: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp-inc 1 | ES582.1/ES584.1: dtseg1 2..32 dtseg2 1..16 dsjw 1..8 dbrp 1..32 dbrp-inc 1 | clock 80000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 To prevent this from happening, we do a local copy of can_priv, work on it, an copy it at the very end of the function (i.e. only if all previous checks succeeded). Once this done, there is no more need to have a temporary variable for a specific parameter. As such, the bittiming and data bittiming (bt and dbt) are directly written to the temporary priv variable. Signed-off-by: Vincent Mailhol --- Hi Marc, Do you think this need a "Fixes" tag? If yes, feel free to add this line to the patch: Fixes: 9859ccd2c8be ("can: introduce the data bitrate configuration for CAN FD") --- drivers/net/can/dev/netlink.c | 86 ++++++++++++++++++----------------- 1 file changed, 45 insertions(+), 41 deletions(-) diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c index 80425636049d..6a14c51a058b 100644 --- a/drivers/net/can/dev/netlink.c +++ b/drivers/net/can/dev/netlink.c @@ -58,14 +58,20 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], struct nlattr *data[], struct netlink_ext_ack *extack) { - struct can_priv *priv = netdev_priv(dev); + /* Work on a local copy of priv to prevent inconsistent value + * in case of early return. net/core/rtnetlink.c has a global + * mutex so static declaration is OK + */ + static struct can_priv priv; int err; /* We need synchronization with dev->stop() */ ASSERT_RTNL(); + memcpy(&priv, netdev_priv(dev), sizeof(priv)); + if (data[IFLA_CAN_BITTIMING]) { - struct can_bittiming bt; + struct can_bittiming *bt = &priv.bittiming; /* Do not allow changing bittiming while running */ if (dev->flags & IFF_UP) @@ -76,28 +82,26 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], * directly via do_set_bitrate(). Bail out if neither * is given. */ - if (!priv->bittiming_const && !priv->do_set_bittiming) + if (!priv.bittiming_const && !priv.do_set_bittiming) return -EOPNOTSUPP; - memcpy(&bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(bt)); - err = can_get_bittiming(dev, &bt, - priv->bittiming_const, - priv->bitrate_const, - priv->bitrate_const_cnt); + memcpy(bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(*bt)); + err = can_get_bittiming(dev, bt, + priv.bittiming_const, + priv.bitrate_const, + priv.bitrate_const_cnt); if (err) return err; - if (priv->bitrate_max && bt.bitrate > priv->bitrate_max) { + if (priv.bitrate_max && bt->bitrate > priv.bitrate_max) { netdev_err(dev, "arbitration bitrate surpasses transceiver capabilities of %d bps\n", - priv->bitrate_max); + priv.bitrate_max); return -EINVAL; } - memcpy(&priv->bittiming, &bt, sizeof(bt)); - - if (priv->do_set_bittiming) { + if (priv.do_set_bittiming) { /* Finally, set the bit-timing registers */ - err = priv->do_set_bittiming(dev); + err = priv.do_set_bittiming(dev); if (err) return err; } @@ -112,11 +116,11 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], if (dev->flags & IFF_UP) return -EBUSY; cm = nla_data(data[IFLA_CAN_CTRLMODE]); - ctrlstatic = priv->ctrlmode_static; + ctrlstatic = priv.ctrlmode_static; maskedflags = cm->flags & cm->mask; /* check whether provided bits are allowed to be passed */ - if (maskedflags & ~(priv->ctrlmode_supported | ctrlstatic)) + if (maskedflags & ~(priv.ctrlmode_supported | ctrlstatic)) return -EOPNOTSUPP; /* do not check for static fd-non-iso if 'fd' is disabled */ @@ -128,16 +132,16 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], return -EOPNOTSUPP; /* clear bits to be modified and copy the flag values */ - priv->ctrlmode &= ~cm->mask; - priv->ctrlmode |= maskedflags; + priv.ctrlmode &= ~cm->mask; + priv.ctrlmode |= maskedflags; /* CAN_CTRLMODE_FD can only be set when driver supports FD */ - if (priv->ctrlmode & CAN_CTRLMODE_FD) { + if (priv.ctrlmode & CAN_CTRLMODE_FD) { dev->mtu = CANFD_MTU; } else { dev->mtu = CAN_MTU; - memset(&priv->data_bittiming, 0, - sizeof(priv->data_bittiming)); + memset(&priv.data_bittiming, 0, + sizeof(priv.data_bittiming)); } } @@ -145,7 +149,7 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], /* Do not allow changing restart delay while running */ if (dev->flags & IFF_UP) return -EBUSY; - priv->restart_ms = nla_get_u32(data[IFLA_CAN_RESTART_MS]); + priv.restart_ms = nla_get_u32(data[IFLA_CAN_RESTART_MS]); } if (data[IFLA_CAN_RESTART]) { @@ -158,7 +162,7 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], } if (data[IFLA_CAN_DATA_BITTIMING]) { - struct can_bittiming dbt; + struct can_bittiming *dbt = &priv.data_bittiming; /* Do not allow changing bittiming while running */ if (dev->flags & IFF_UP) @@ -169,31 +173,29 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], * directly via do_set_bitrate(). Bail out if neither * is given. */ - if (!priv->data_bittiming_const && !priv->do_set_data_bittiming) + if (!priv.data_bittiming_const && !priv.do_set_data_bittiming) return -EOPNOTSUPP; - memcpy(&dbt, nla_data(data[IFLA_CAN_DATA_BITTIMING]), - sizeof(dbt)); - err = can_get_bittiming(dev, &dbt, - priv->data_bittiming_const, - priv->data_bitrate_const, - priv->data_bitrate_const_cnt); + memcpy(dbt, nla_data(data[IFLA_CAN_DATA_BITTIMING]), + sizeof(*dbt)); + err = can_get_bittiming(dev, dbt, + priv.data_bittiming_const, + priv.data_bitrate_const, + priv.data_bitrate_const_cnt); if (err) return err; - if (priv->bitrate_max && dbt.bitrate > priv->bitrate_max) { + if (priv.bitrate_max && dbt->bitrate > priv.bitrate_max) { netdev_err(dev, "canfd data bitrate surpasses transceiver capabilities of %d bps\n", - priv->bitrate_max); + priv.bitrate_max); return -EINVAL; } - memcpy(&priv->data_bittiming, &dbt, sizeof(dbt)); - can_calc_tdco(dev); - if (priv->do_set_data_bittiming) { + if (priv.do_set_data_bittiming) { /* Finally, set the bit-timing registers */ - err = priv->do_set_data_bittiming(dev); + err = priv.do_set_data_bittiming(dev); if (err) return err; } @@ -201,28 +203,30 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], if (data[IFLA_CAN_TERMINATION]) { const u16 termval = nla_get_u16(data[IFLA_CAN_TERMINATION]); - const unsigned int num_term = priv->termination_const_cnt; + const unsigned int num_term = priv.termination_const_cnt; unsigned int i; - if (!priv->do_set_termination) + if (!priv.do_set_termination) return -EOPNOTSUPP; /* check whether given value is supported by the interface */ for (i = 0; i < num_term; i++) { - if (termval == priv->termination_const[i]) + if (termval == priv.termination_const[i]) break; } if (i >= num_term) return -EINVAL; /* Finally, set the termination value */ - err = priv->do_set_termination(dev, termval); + err = priv.do_set_termination(dev, termval); if (err) return err; - priv->termination = termval; + priv.termination = termval; } + memcpy(netdev_priv(dev), &priv, sizeof(priv)); + return 0; } -- 2.31.1