From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F265AC433EF for ; Mon, 6 Dec 2021 15:31:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1388040AbhLFPcP (ORCPT ); Mon, 6 Dec 2021 10:32:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376970AbhLFPUx (ORCPT ); Mon, 6 Dec 2021 10:20:53 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0BC0BC07E5E2; Mon, 6 Dec 2021 07:14:22 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9E39A61320; Mon, 6 Dec 2021 15:14:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 871A7C341C5; Mon, 6 Dec 2021 15:14:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1638803661; bh=LOtJeSPEIh8A6KC4te5DMVdDABvBNATBWaW+pIT2q/g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CC20Z2o2VwQNcGUT1GCREGuCKxtp/O+nFOAmbp/U9IwMajb3oG51SrYReDgr0Pqk3 K8lV6pYjZ9MOKpcQ89c4tkfllrhXSU1VkMXdcLosSqMsBT8aMpk6oER+uQyEGhXqU/ TNo9yYZhAA0r0SkiGvwQ+OWK9lWL1stJaJ5CYRAY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rob Herring , Baruch Siach , Johan Hovold Subject: [PATCH 5.4 64/70] serial: core: fix transmit-buffer reset and memleak Date: Mon, 6 Dec 2021 15:57:08 +0100 Message-Id: <20211206145554.137319150@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211206145551.909846023@linuxfoundation.org> References: <20211206145551.909846023@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Johan Hovold commit 00de977f9e0aa9760d9a79d1e41ff780f74e3424 upstream. Commit 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") converted serial core to use tty_port_close() but failed to notice that the transmit buffer still needs to be freed on final close. Not freeing the transmit buffer means that the buffer is no longer cleared on next open so that any ioctl() waiting for the buffer to drain might wait indefinitely (e.g. on termios changes) or that stale data can end up being transmitted in case tx is restarted. Furthermore, the buffer of any port that has been opened would leak on driver unbind. Note that the port lock is held when clearing the buffer pointer due to the ldisc race worked around by commit a5ba1d95e46e ("uart: fix race between uart_put_char() and uart_shutdown()"). Also note that the tty-port shutdown() callback is not called for console ports so it is not strictly necessary to free the buffer page after releasing the lock (cf. d72402145ace ("tty/serial: do not free trasnmit buffer page under port lock")). Link: https://lore.kernel.org/r/319321886d97c456203d5c6a576a5480d07c3478.1635781688.git.baruch@tkos.co.il Fixes: 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") Cc: stable@vger.kernel.org # 4.9 Cc: Rob Herring Reported-by: Baruch Siach Tested-by: Baruch Siach Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20211108085431.12637-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1573,6 +1573,7 @@ static void uart_tty_port_shutdown(struc { struct uart_state *state = container_of(port, struct uart_state, port); struct uart_port *uport = uart_port_check(state); + char *buf; /* * At this point, we stop accepting input. To do this, we @@ -1594,8 +1595,18 @@ static void uart_tty_port_shutdown(struc */ tty_port_set_suspended(port, 0); - uart_change_pm(state, UART_PM_STATE_OFF); + /* + * Free the transmit buffer. + */ + spin_lock_irq(&uport->lock); + buf = state->xmit.buf; + state->xmit.buf = NULL; + spin_unlock_irq(&uport->lock); + + if (buf) + free_page((unsigned long)buf); + uart_change_pm(state, UART_PM_STATE_OFF); } static void uart_wait_until_sent(struct tty_struct *tty, int timeout)