From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 7E4BE423782; Thu, 30 Jul 2026 14:56:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423368; cv=none; b=WrJQ9jqO+/Reaq3Tl4sNToAcIx+cohX1CtCG2MP6zc1M0u50/HWwTgAWJiTkO3JmSuQPI+m/iass6wGtu9Sc1zewP4F3T5URVtn8POGr2NvzIkfyc171I8tcU7a0ibIulMoXqMnfUx2bNKPbJrnSRYj0DwmqAIKQTVbca7EEUiU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423368; c=relaxed/simple; bh=Vsw6OCkQ6F2KmJPdBSgxP2oTLvnebxEx+aNni81ON5E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=psx5Vz55m4PAuWncH7XSogqJRMPz7mQ2olHhz2JtA52IXrdQvNcwSec1O8+7UFwtVg8wXbgqpaREgRIGB1UHnET5SOLckm0ApkZNu6UR7q8f82VH2G4faymC7CmminiVCqlhX+rVzM/poe8qQnBwre9Exfowqp8wA69WOHXzjr4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Cd7NLT7x; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Cd7NLT7x" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3DB21F00A3E; Thu, 30 Jul 2026 14:56:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785423367; bh=qZRhKsnVnAlJpA1oh4W9OXwyE1K9sv/DOw1xqsgW5qc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Cd7NLT7x1cwzj6ZAObQ3NoJFYUPayJMTGLkCbElvEI1ITllE4qJOPlY6dWJyOz1BD K+3kL9QZoeh81yDqiy4HN0j0GUnbUa/aFY8B1L6W66Pnh9j2FLHIZ6iIeUdONG8N+t 33QqBe+TR9C3IX1183stHfgP8CJsnbUmVtVn82SM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, sashiko-bot@kernel.org, Oliver Hartkopp , stable@kernel.org, Marc Kleine-Budde , Sasha Levin Subject: [PATCH 6.18 020/675] can: bcm: add missing device refcount for CAN filter removal Date: Thu, 30 Jul 2026 16:05:50 +0200 Message-ID: <20260730141445.550731533@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@linuxfoundation.org> User-Agent: quilt/0.69 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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oliver Hartkopp commit d59948293ea34b6337ce2b5febab8510de70048c upstream. sashiko-bot remarked a problem with a concurrent device unregistration in isotp.c which also is present in the bcm.c code. A former fix for raw.c commit c275a176e4b6 ("can: raw: add missing refcount for memory leak fix") introduced a netdevice_tracker which solves the issue for bcm.c too. bcm_release(), bcm_delete_rx_op() and bcm_notifier() relied on dev_get_by_index(ifindex) to re-find the device for an rx_op before unregistering its filter. If a concurrent NETDEV_UNREGISTER has already unlisted the device from the ifindex table, that lookup fails and can_rx_unregister() is silently skipped, leaving a stale CAN filter pointing at the soon-to-be-freed bcm_op/socket. Hold a netdev_hold()/netdev_put() tracked reference on op->rx_reg_dev from the moment the rx filter is registered in bcm_rx_setup() until it is unregistered in bcm_rx_unreg(), and use that reference directly in bcm_release() and bcm_delete_rx_op() instead of re-looking the device up by ifindex. Reported-by: sashiko-bot@kernel.org Closes: https://sashiko.dev/#/patchset/20260707094716.63578-1-socketcan@hartkopp.net Fixes: ffd980f976e7 ("[CAN]: Add broadcast manager (bcm) protocol") Signed-off-by: Oliver Hartkopp Link: https://patch.msgid.link/20260714-bcm_fixes-v15-8-562f7e3e42da@hartkopp.net Cc: stable@kernel.org Signed-off-by: Marc Kleine-Budde Signed-off-by: Oliver Hartkopp Signed-off-by: Sasha Levin --- net/can/bcm.c | 44 ++++++++++++++++++++++++-------------------- 1 file changed, 24 insertions(+), 20 deletions(-) diff --git a/net/can/bcm.c b/net/can/bcm.c index 2de64d7a99a216..ca0dd2229f5b86 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -932,6 +932,7 @@ static void bcm_rx_unreg(struct net_device *dev, struct bcm_op *op) /* mark as removed subscription */ op->rx_reg_dev = NULL; + dev_put(dev); } else printk(KERN_ERR "can-bcm: bcm_rx_unreg: registered device " "mismatch %p %p\n", op->rx_reg_dev, dev); @@ -962,17 +963,14 @@ static int bcm_delete_rx_op(struct list_head *ops, struct bcm_msg_head *mh, * Only remove subscriptions that had not * been removed due to NETDEV_UNREGISTER * in bcm_notifier() + * + * op->rx_reg_dev is a tracked reference taken + * when the subscription was registered, so it + * stays valid here even if a concurrent + * NETDEV_UNREGISTER already unlisted the dev. */ - if (op->rx_reg_dev) { - struct net_device *dev; - - dev = dev_get_by_index(sock_net(op->sk), - op->ifindex); - if (dev) { - bcm_rx_unreg(dev, op); - dev_put(dev); - } - } + if (op->rx_reg_dev) + bcm_rx_unreg(op->rx_reg_dev, op); } else can_rx_unregister(sock_net(op->sk), NULL, op->can_id, @@ -1491,7 +1489,15 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg, bcm_rx_handler, op, "bcm", sk); - op->rx_reg_dev = dev; + /* keep a reference so that a later + * unregister can safely reach the device even + * if a concurrent NETDEV_UNREGISTER has + * already unlisted it by ifindex + */ + if (!err) { + op->rx_reg_dev = dev; + dev_hold(dev); + } dev_put(dev); } else { /* the requested device is gone - do not @@ -1864,16 +1870,14 @@ static int bcm_release(struct socket *sock) * Only remove subscriptions that had not * been removed due to NETDEV_UNREGISTER * in bcm_notifier() + * + * op->rx_reg_dev is a tracked reference taken + * when the subscription was registered, so it + * stays valid here even if a concurrent + * NETDEV_UNREGISTER already unlisted the device. */ - if (op->rx_reg_dev) { - struct net_device *dev; - - dev = dev_get_by_index(net, op->ifindex); - if (dev) { - bcm_rx_unreg(dev, op); - dev_put(dev); - } - } + if (op->rx_reg_dev) + bcm_rx_unreg(op->rx_reg_dev, op); } else can_rx_unregister(net, NULL, op->can_id, REGMASK(op->can_id), -- 2.53.0