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 83B3B43A7F8; Mon, 31 Aug 2026 13:56:32 +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=1788184593; cv=none; b=HRhKMn8YL4F3cHqOh9Zuo2CJOQcJkNAc778PZw2qINR1Z7Z4lZv9P0EKGssg7oVTTESzIyUCZgLmA8TOAKMBWdHxvXH6exL0koA8XzObu3qYezoPdqR9eFn5AAiZbqK+MJg1NiIW2hwUKpGsyHKM9TM6z3EVSrd9EEDwY8IfbxM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788184593; c=relaxed/simple; bh=Z5mhGBASgu6wmQXSv2+tc1TN21IOgUp7gZnL2kppN1U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ABgGy0P5qLKSeJEoOXUU7ltIdKBLghYaJCnyTkgvL589Ns457HHu+0bR2xT18sHLrNOOnAWjW1wcQzBKz1B2K3l4JIBH7lxaXuEcpEQ9RXz51woc2K/OlBI+9FXym/+8Bp2mCGDt48U2f9HgM3br9HToQpZ9uecpKZ8gx79lItU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pDuB04/S; 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="pDuB04/S" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F49E1F000E9; Mon, 31 Aug 2026 13:56:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788184592; bh=pBjOo9BaT6/g192FzuDToKyD75d23TR5Ei5GfBcMBrw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=pDuB04/SSzR/ldXqCh2n1XW+3bRUunCh/3rWzm6naJfgf0sNXWwyikQ6jR/f7t0ZM qcUntFl+gJnWp1BAvKVUjTp0jz8QHeg62dzXHGtmy15Qf6zDEFa/eFR1uvbUL+dU1C UHtG5CcbiBs7TKmQzybol4hd1symYoNqDAR1cKnA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mathias Nyman , Lucas De Marchi Subject: [PATCH 6.6 60/91] xhci: dbgtty: Fix unregister on tty_register_driver() failure Date: Mon, 31 Aug 2026 15:34:48 +0200 Message-ID: <20260831133402.839171452@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133359.468089036@linuxfoundation.org> References: <20260831133359.468089036@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: 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 @@ -619,6 +619,7 @@ 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;