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 D54C72D29CF for ; Mon, 20 Jul 2026 15:15:27 +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=1784560529; cv=none; b=OaEgNFfRb5rIVpfGN/1bAQgSGT7bHxCOdhZFxedTEkK3TFW5+7KKrbj8PzI2bcN+oaNUYxp9gUkD4uavS8nfJrU2CzvU3tXtAGB/WZGsIvT8w5HZ5NMaq19pNtjjamhUCbXmbAKdfID99FU0tSfQp6D13/ThWRGIiQUAddzjCbc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784560529; c=relaxed/simple; bh=bGdX5EbxUamjfiQDTIQa58GeWIndcw8xNEtLlT7B+ys=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=A/9jVCzkz642kvYnZDWBcQ0YSMpI+g0ZDFHajL+6PgK0M4ZAtcjfeiMfNuLM7apJXsLUiZnlrTULympmak+ISq1cuoISW+KNDh/EHdltdLyaMXGLVYkkcipcSbnaQUWFSNy5StFtRNsQbPjowLWrTnidfWlLY+T1+cj/wcQA7t4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Wk07JpQq; 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="Wk07JpQq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 488E61F000E9; Mon, 20 Jul 2026 15:15:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784560527; bh=jPnaRRQIe6JA1aPukLZ+VdS7sih0MprPZPf/Ldlc4nA=; h=Subject:To:Cc:From:Date; b=Wk07JpQqYGr1c9utSB9Od6fBfwWUa/6Ta49/JVSVkN80WrGsqeUnLZLmiJ1d9dXCz gTUzmNJSNH9wgquADjc69cSCU+lKaFbpKAe5Y6Rv33qXoqOUYV809VxqNHm6EOeYkC jBkNuyQRYKD1sDzvt/sZMn9Httb9VFcPoyj1J1tQ= Subject: FAILED: patch "[PATCH] can: bcm: add missing device refcount for CAN filter removal" failed to apply to 6.6-stable tree To: socketcan@hartkopp.net,mkl@pengutronix.de Cc: From: Date: Mon, 20 Jul 2026 17:14:38 +0200 Message-ID: <2026072038-cosmos-bulge-2f0e@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x d59948293ea34b6337ce2b5febab8510de70048c # git commit -s git send-email --to '' --in-reply-to '2026072038-cosmos-bulge-2f0e@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From d59948293ea34b6337ce2b5febab8510de70048c Mon Sep 17 00:00:00 2001 From: Oliver Hartkopp Date: Tue, 14 Jul 2026 18:55:30 +0200 Subject: [PATCH] can: bcm: add missing device refcount for CAN filter removal 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 diff --git a/net/can/bcm.c b/net/can/bcm.c index 2d9c9cd74536..25842061800b 100644 --- a/net/can/bcm.c +++ b/net/can/bcm.c @@ -128,6 +128,7 @@ struct bcm_op { struct canfd_frame last_sframe; struct sock *sk; struct net_device *rx_reg_dev; + netdevice_tracker rx_reg_dev_tracker; spinlock_t bcm_tx_lock; /* protect tx data and timer updates */ spinlock_t bcm_rx_update_lock; /* protect filter/timer data updates */ }; @@ -937,6 +938,7 @@ static void bcm_rx_unreg(struct net_device *dev, struct bcm_op *op) /* mark as removed subscription */ op->rx_reg_dev = NULL; + netdev_put(dev, &op->rx_reg_dev_tracker); } else printk(KERN_ERR "can-bcm: bcm_rx_unreg: registered device " "mismatch %p %p\n", op->rx_reg_dev, dev); @@ -967,17 +969,14 @@ 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, @@ -1496,7 +1495,17 @@ 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 tracked 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; + netdev_hold(dev, + &op->rx_reg_dev_tracker, + GFP_KERNEL); + } dev_put(dev); } else { /* the requested device is gone - do not @@ -1873,16 +1882,14 @@ 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),