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 F3CEC35C6AC; Tue, 21 Jul 2026 21:17:06 +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=1784668630; cv=none; b=WTQziPtpr/j/Fitdk0SFpCLTQt3XWDVgRc1cshiY1hI5eDA/queE2kZcI5DDm+MXaP7JZSBQoRSdUjueMmfYIuhEdwkmq3K9UWxG5RPkJtw7rcunGiyikFfeLbGnLzj2IhtH023gmE0+8aTG5vTrBUmXlUzx8YNpW0Icyied9DI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784668630; c=relaxed/simple; bh=NSDg9qQ9P8uRAsL4FY+/FHZ3ZVLsYpwVJgo865iRDN0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GDpcONMBNp1jDN10kNqxvdvpfrD+n6uACrlXo09TGJ7NK/l4YbNlLIp1S102tehigTjGuNIlxDVnzUTXGQlhsLAYfBJPOkGWiUjnb0wltNq9camTCj9dcvPeLkjwoUrB9UDL7P7OE2JAQNBGWWuyZBU9li3BqORl5UxcovtcRJo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RK4SEys9; 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="RK4SEys9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 492BB1F000E9; Tue, 21 Jul 2026 21:17:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784668625; bh=0gbGlVcQlkXRzt9GMziosJ17phRCWISXn3dZa88mhP4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=RK4SEys92wDU2i8DkPlwlQe3EBBhVuFSjrNwzXLKIQ9hrdTFTZxsdGqUSC0tSfeQt +eZuvnjpDyvnSGDD8rVseJ6eJ8Onq+byWiP1ca8PAX05hK5yGnjJizaj1kF80u+ML6 ZuAiqyPZGZQzBH8+4Kj0ZqGd2ZtPA6bvA9AUiYQo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alberto Ruiz , Miklos Szeredi Subject: [PATCH 6.1 0248/1067] fuse: fix device node leak in cuse_process_init_reply() Date: Tue, 21 Jul 2026 17:14:09 +0200 Message-ID: <20260721152430.146427232@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152424.521567757@linuxfoundation.org> References: <20260721152424.521567757@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alberto Ruiz commit 9fa4f7a53406430ee9982f2f636a15b338185122 upstream. If device_add() succeeds during CUSE initialization but a subsequent step (cdev_alloc() or cdev_add()) fails, the error path calls put_device() without first calling device_del(). This leaks the devtmpfs entry created by device_add(), leaving a stale /dev/ node that persists until reboot. Since the cuse_conn is never linked into cuse_conntbl on the failure path, cuse_channel_release() sees cc->dev == NULL and skips device_unregister(), so no other code path cleans up the node. This has several consequences: - The device name is permanently poisoned: any subsequent attempt to create a CUSE device with the same name hits the stale sysfs entry, device_add() fails, and the new device is aborted. - The collision manifests as ENODEV returned to userspace with no dmesg diagnostic, making it very difficult to debug. - The failure is self-perpetuating: once a name is leaked, all future attempts with that name fail identically. Fix this by introducing an err_dev label that calls device_del() to undo device_add() before falling through to err_unlock. The existing err_unlock path from a device_add() failure correctly skips device_del() since the device was never added. Testing instructions can be found at the lore link below. Link: https://lore.kernel.org/all/20260408-wip-cuse-leak-fix-v1-0-1c028d575e97@redhat.com/ Signed-off-by: Alberto Ruiz Fixes: 151060ac1314 ("CUSE: implement CUSE - Character device in Userspace") Cc: stable@vger.kernel.org Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/fuse/cuse.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/fs/fuse/cuse.c +++ b/fs/fuse/cuse.c @@ -386,7 +386,7 @@ static void cuse_process_init_reply(stru rc = -ENOMEM; cdev = cdev_alloc(); if (!cdev) - goto err_unlock; + goto err_dev; cdev->owner = THIS_MODULE; cdev->ops = &cuse_frontend_fops; @@ -412,6 +412,8 @@ out: err_cdev: cdev_del(cdev); +err_dev: + device_del(dev); err_unlock: mutex_unlock(&cuse_lock); put_device(dev);