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 96E5E471435; Tue, 21 Jul 2026 20:25:54 +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=1784665555; cv=none; b=hmL1ZRHoCkefb+GkdyWLa2OFVEbxpj1iyfna6vX88yNuik3EqgO7SnAGuC7I1ommhEHJvAy8OjNeJIwP3nlwxFq78EZn5z6lXMKQW0bHpcxHocQk3m7rPO4Gq7ya7XoY/EEgzW6kF124/kDD6yLL8919C3RFNGo6ZuwYsjRv6U4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784665555; c=relaxed/simple; bh=ETMSNonKVKM30csmytFK5XUxQ0Xpvn7J/GINXJyc61E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Bqic8aANgHZYyGmGeZzp/Bs1Q0y3KP/3BEdyYGQHKgKUY5CriW3TrapMH4mvjcl3V5BZEu/+PV3xUsJ2YIdWasg+unL6W2r5ikJ/zf/klgTvc3GqdLT7EVawIO4WUHbX2S6tr1a44fRIGEp0NbPCN1TjzIuqaOCK6PfeRr/I56I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aQZB3W/C; 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="aQZB3W/C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 07DF11F000E9; Tue, 21 Jul 2026 20:25:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784665554; bh=8UUyjBP/jwTkKotJ7t4Wjc0opAO23JRLX/99fRUrEPo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=aQZB3W/Cq1Hta+mYTz6i4Yi+fWeLc5KW1ELMdCe6DzZWef9MsH9k6yQnjLkg/LLaH G7Hm+ocuysKtURYxNnAr6z3+gc0wN+IU58a3/DITvdvz4eY+zZh6RB4VrEc4e9rrZq O5LIuuAFb9lqI/QeVjnJyRUi9OnH7arBExXgE7gg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alberto Ruiz , Miklos Szeredi Subject: [PATCH 6.6 0321/1266] fuse: fix device node leak in cuse_process_init_reply() Date: Tue, 21 Jul 2026 17:12:38 +0200 Message-ID: <20260721152449.020373760@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152441.786066624@linuxfoundation.org> References: <20260721152441.786066624@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 6.6-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);