[PATCH 4.18 180/235] tty: fix termios input-speed encoding

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

[ Upstream commit fada18c48d774b9e837928ecdce6a5d5fdd11ee7 ]

Make sure to clear the CIBAUD bits before OR-ing the new mask when
encoding the termios input baud rate.

This could otherwise lead to an incorrect input rate being reported back
and incidentally set on subsequent termios updates.

Fixes: edc6afc54968 ("[PATCH] tty: switch to ktermios and new framework")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/tty/tty_baudrate.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/tty/tty_baudrate.c
+++ b/drivers/tty/tty_baudrate.c
@@ -173,6 +173,9 @@ void tty_termios_encode_baud_rate(struct
 		iclose = 0;
 #endif
 	termios->c_cflag &= ~CBAUD;
+#ifdef IBSHIFT
+	termios->c_cflag &= ~(CBAUD << IBSHIFT);
+#endif
 
 	/*
 	 *	Our goal is to find a close match to the standard baud rate