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 EA4F2559CB1; Mon, 31 Aug 2026 13:47:16 +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=1788184040; cv=none; b=GdY1nDy3hVaAZoUMY3dtT+KeDCPv5ngoAGPusfuRBVt39t+hzhr3noxFweWZ/7f2VLWIi8PdiR7WSeRheAGyz7ix8Hu/BuABNzalY4aG4jOfklDT1V8JIAb9zr/4IKD9+zQOICPAVSXJheyDvCC6+iKMU2HU2cAos2DHh9hrDBk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788184040; c=relaxed/simple; bh=kH69iWh0feqmj+H1R0EAK1lw/P8oqi7VDnJjCNhEFzU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f1koaRJIMUWi7dp3P/AmpDNWYrL4rUPg+Zed92t8oM2EHRQco3Xxfxp4k16afkzGo3P3xlsF5BUmg+LjSRtEfxQtxLl/G4i8uG4f7q08rTJeTyi3oh2CbO9YJJkSa+tw/uOVy2qjy6MYwWU+n9LuvWBzzpCj8qRAUbcd/MTRncY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=C4xgkruc; 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="C4xgkruc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0BB1E1F00ACA; Mon, 31 Aug 2026 13:47:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788184036; bh=4lOq/NooncOV/CWfdrl92DytmwyQ+D8dfEVMI0s5Ajc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=C4xgkruch9U8CZGZ6yj3tmf0okIaN3AIUy5lEM+bOCZad29U34H0a+TqC5FA4sLmr OUjf60y1Y1B5dpUooW0Z4qBtFG1HIoWjNAgMQu1vP3zzd/2njViDDkHFiDDO9Cyigc VlSpzMrzdid0y9vrWCe0o0bCfrMo9rBbRj39YFnw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mathias Nyman , Lucas De Marchi Subject: [PATCH 6.18 34/83] xhci: dbgtty: Fix unregister on tty_register_driver() failure Date: Mon, 31 Aug 2026 15:34:10 +0200 Message-ID: <20260831133401.184866968@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133359.207714926@linuxfoundation.org> References: <20260831133359.207714926@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: Lucas De Marchi commit a916fa66a43e10f63198b6ce978badffc678821a upstream. If tty_register_driver() fails, it drops the reference, but fails to set the global dbc_tty_driver to NULL, causing the unregister to be called again when module exits. On module unload dbc_tty_exit() only gates its cleanup on the driver pointer being non-NULL, so it operates on the already-freed driver: module_init(xhci_hcd_init) xhci_hcd_init() xhci_dbc_init() [return value ignored] dbc_tty_init() tty_register_driver() fails tty_driver_kref_put() -> driver freed (dbc_tty_driver left dangling) ... module_exit(xhci_hcd_fini) xhci_hcd_fini() xhci_dbc_exit() dbc_tty_exit() if (dbc_tty_driver) -> true (dangling) tty_unregister_driver() -> use-after-free Fixes: 4521f1613940 ("xhci: dbctty: split dbc tty driver registration and unregistration functions.") Cc: stable@vger.kernel.org # v5.10 Cc: Mathias Nyman Cc: Greg Kroah-Hartman Signed-off-by: Lucas De Marchi Signed-off-by: Mathias Nyman Link: https://patch.msgid.link/20260806142113.2436238-8-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/xhci-dbgtty.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/usb/host/xhci-dbgtty.c +++ b/drivers/usb/host/xhci-dbgtty.c @@ -651,6 +651,7 @@ int dbc_tty_init(void) pr_err("Can't register dbc tty driver\n"); tty_driver_kref_put(dbc_tty_driver); idr_destroy(&dbc_tty_minors); + dbc_tty_driver = NULL; } return ret;