From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6E8ED157E6B; Wed, 30 Jul 2025 09:44:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753868673; cv=none; b=u/vPQzxkOkK5l/27Wtu6Gzua96YhBvGxDUgQbqDqASs7MKMwz/Ia7dP5uJDmnhZN/tgjmIdisu4g1vBT0mr/iGTpwtgKoa9wTKkYH8ICSwUcKBDqGSmzDt+qMW8lpv4GwtYq/EqiQw90hj0dWSvR2R+KWvUtk16h+uQfT+IXtXg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753868673; c=relaxed/simple; bh=eCtIvERHBfHdDYGhhzB2oMqgHyL4/Gst/y290dxSYRA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=guUbMh3o/b22fwLUZTDho6Vm5SEroFkC/pIgqJxANgsRXTrOkVLAP6hbD75u+HHPwT6N968P85F5AJ0zhHkZPBVezU6RPTZzKUqiMXGGs7DaUINFpHYruRlo4JTLaH/T6dsJfN9frOASsDmoUxZ2c81lw3rJs5rFjbqAANgfP8E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sOJUyJ9o; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sOJUyJ9o" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 22AA7C4CEF5; Wed, 30 Jul 2025 09:44:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1753868673; bh=eCtIvERHBfHdDYGhhzB2oMqgHyL4/Gst/y290dxSYRA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sOJUyJ9oYTBLZvHTO1KTUfnmQ/0hnnoOL6ZV5paKszuch4gV4Q8jRK/RTMFE2Hws9 VFdhTUiAjhny4+a99IqfTGv8AFrOKXzu4nIoacH9/r/pJ6SwdEvM0bYAceoAO72dSy 71xBS4qGwB+1Kks0OxTpr8dV1C5N84dxjE9uWIso= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrei Lalaev , Marc Kleine-Budde , Sasha Levin Subject: [PATCH 6.12 030/117] can: netlink: can_changelink(): fix NULL pointer deref of struct can_priv::do_set_mode Date: Wed, 30 Jul 2025 11:34:59 +0200 Message-ID: <20250730093234.738002245@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250730093233.592541778@linuxfoundation.org> References: <20250730093233.592541778@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marc Kleine-Budde [ Upstream commit c1f3f9797c1f44a762e6f5f72520b2e520537b52 ] Andrei Lalaev reported a NULL pointer deref when a CAN device is restarted from Bus Off and the driver does not implement the struct can_priv::do_set_mode callback. There are 2 code path that call struct can_priv::do_set_mode: - directly by a manual restart from the user space, via can_changelink() - delayed automatic restart after bus off (deactivated by default) To prevent the NULL pointer deference, refuse a manual restart or configure the automatic restart delay in can_changelink() and report the error via extack to user space. As an additional safety measure let can_restart() return an error if can_priv::do_set_mode is not set instead of dereferencing it unchecked. Reported-by: Andrei Lalaev Closes: https://lore.kernel.org/all/20250714175520.307467-1-andrey.lalaev@gmail.com Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface") Link: https://patch.msgid.link/20250718-fix-nullptr-deref-do_set_mode-v1-1-0b520097bb96@pengutronix.de Signed-off-by: Marc Kleine-Budde Signed-off-by: Sasha Levin --- drivers/net/can/dev/dev.c | 12 +++++++++--- drivers/net/can/dev/netlink.c | 12 ++++++++++++ 2 files changed, 21 insertions(+), 3 deletions(-) diff --git a/drivers/net/can/dev/dev.c b/drivers/net/can/dev/dev.c index 681643ab37804..63e4a495b1371 100644 --- a/drivers/net/can/dev/dev.c +++ b/drivers/net/can/dev/dev.c @@ -147,13 +147,16 @@ void can_change_state(struct net_device *dev, struct can_frame *cf, EXPORT_SYMBOL_GPL(can_change_state); /* CAN device restart for bus-off recovery */ -static void can_restart(struct net_device *dev) +static int can_restart(struct net_device *dev) { struct can_priv *priv = netdev_priv(dev); struct sk_buff *skb; struct can_frame *cf; int err; + if (!priv->do_set_mode) + return -EOPNOTSUPP; + if (netif_carrier_ok(dev)) netdev_err(dev, "Attempt to restart for bus-off recovery, but carrier is OK?\n"); @@ -175,10 +178,14 @@ static void can_restart(struct net_device *dev) if (err) { netdev_err(dev, "Restart failed, error %pe\n", ERR_PTR(err)); netif_carrier_off(dev); + + return err; } else { netdev_dbg(dev, "Restarted\n"); priv->can_stats.restarts++; } + + return 0; } static void can_restart_work(struct work_struct *work) @@ -203,9 +210,8 @@ int can_restart_now(struct net_device *dev) return -EBUSY; cancel_delayed_work_sync(&priv->restart_work); - can_restart(dev); - return 0; + return can_restart(dev); } /* CAN bus-off diff --git a/drivers/net/can/dev/netlink.c b/drivers/net/can/dev/netlink.c index 01aacdcda2606..abe8dc051d94f 100644 --- a/drivers/net/can/dev/netlink.c +++ b/drivers/net/can/dev/netlink.c @@ -285,6 +285,12 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], } if (data[IFLA_CAN_RESTART_MS]) { + if (!priv->do_set_mode) { + NL_SET_ERR_MSG(extack, + "Device doesn't support restart from Bus Off"); + return -EOPNOTSUPP; + } + /* Do not allow changing restart delay while running */ if (dev->flags & IFF_UP) return -EBUSY; @@ -292,6 +298,12 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], } if (data[IFLA_CAN_RESTART]) { + if (!priv->do_set_mode) { + NL_SET_ERR_MSG(extack, + "Device doesn't support restart from Bus Off"); + return -EOPNOTSUPP; + } + /* Do not allow a restart while not running */ if (!(dev->flags & IFF_UP)) return -EINVAL; -- 2.39.5