From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:56406 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732118AbeIXSYS (ORCPT ); Mon, 24 Sep 2018 14:24:18 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johan Hovold , Sasha Levin Subject: [PATCH 4.14 128/173] tty: fix termios input-speed encoding when using BOTHER Date: Mon, 24 Sep 2018 13:52:42 +0200 Message-Id: <20180924113125.249013006@linuxfoundation.org> In-Reply-To: <20180924113114.334025954@linuxfoundation.org> References: <20180924113114.334025954@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold [ Upstream commit 1cee38f0363a88db374e50b232ca17b9a4c12fa0 ] When the termios CIBAUD bits are left unset (i.e. B0), we use the same output and input speed and should leave CIBAUD unchanged. When the user requests a rate using BOTHER and c_ospeed which the driver cannot set exactly, the driver can report back the actual baud rate using tty_termios_encode_baud_rate(). If this rate is close enough to a standard rate however, we could end up setting CIBAUD to a Bfoo value despite the user having left it unset. This in turn could lead to an unexpected input rate being set on subsequent termios updates. Fix this by using a zero tolerance value also for the input rate when CIBAUD is clear so that the matching logic works as expected. Fixes: 78137e3b34e1 ("[PATCH] tty: improve encode_baud_rate logic") Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_baudrate.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/drivers/tty/tty_baudrate.c +++ b/drivers/tty/tty_baudrate.c @@ -156,16 +156,20 @@ void tty_termios_encode_baud_rate(struct termios->c_ospeed = obaud; #ifdef BOTHER + if ((termios->c_cflag >> IBSHIFT) & CBAUD) + ibinput = 1; /* An input speed was specified */ + /* If the user asked for a precise weird speed give a precise weird answer. If they asked for a Bfoo speed they may have problems digesting non-exact replies so fuzz a bit */ - if ((termios->c_cflag & CBAUD) == BOTHER) + if ((termios->c_cflag & CBAUD) == BOTHER) { oclose = 0; + if (!ibinput) + iclose = 0; + } if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER) iclose = 0; - if ((termios->c_cflag >> IBSHIFT) & CBAUD) - ibinput = 1; /* An input speed was specified */ #endif termios->c_cflag &= ~CBAUD;