linux-kernel - [PATCH tty-next v1 2/4] serial: 8250: Do not set UART_LSR_THRE in @read_status

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20241216171244.12783-3-john.ogness@linutronix.de>
Date: Mon, 16 Dec 2024 18:18:42 +0106
From: John Ogness <john.ogness@...utronix.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jirislaby@...nel.org>,
	Esben Haabendal <esben@...nix.com>,
	linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Kevin Hilman <khilman@...libre.com>,
	Markus Schneider-Pargmann <msp@...libre.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Udit Kumar <u-kumar1@...com>,
	Griffin Kroah-Hartman <griffin@...ah.com>,
	Arnd Bergmann <arnd@...db.de>,
	Rengarajan S <rengarajan.s@...rochip.com>,
	Lino Sanfilippo <l.sanfilippo@...bus.com>,
	Niklas Schnelle <schnelle@...ux.ibm.com>,
	Serge Semin <fancer.lancer@...il.com>,
	Peter Collingbourne <pcc@...gle.com>
Subject: [PATCH tty-next v1 2/4] serial: 8250: Do not set UART_LSR_THRE in @read_status_mask

Since Linux 2.1.8 @read_status_mask is no longer used as a
general control of which bits are used from the LSR register.
Instead it has become an additional mask applied to
@ignore_status_mask. Since UART_LSR_THRE is never set for
@ignore_status_mask, it serves no purpose to set it for
@read_status_mask. In fact, it propagates the misconception
that @read_status_mask can be used as a general mask for LSR
bits.

Do not set UART_LSR_THRE for @read_status_mask.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 drivers/tty/serial/8250/8250_omap.c | 2 +-
 drivers/tty/serial/8250/8250_port.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 9eb9aa766811..5290aed76a5e 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -412,7 +412,7 @@ static void omap_8250_set_termios(struct uart_port *port,
 	 */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
-	up->port.read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
+	up->port.read_status_mask = UART_LSR_OE | UART_LSR_DR;
 	if (termios->c_iflag & INPCK)
 		up->port.read_status_mask |= UART_LSR_FE | UART_LSR_PE;
 	if (termios->c_iflag & (IGNBRK | PARMRK))
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 4d742bfb7e9a..a5c1b069c67b 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2786,7 +2786,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 	 */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
-	port->read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
+	port->read_status_mask = UART_LSR_OE | UART_LSR_DR;
 	if (termios->c_iflag & INPCK)
 		port->read_status_mask |= UART_LSR_FE | UART_LSR_PE;
 	if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
-- 
2.39.5