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authorPeter Hurley <peter@hurleysoftware.com>2014-09-10 23:06:35 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-09-24 08:19:36 +0400
commitc274f6ef1c6665632767d32e4ab912aad839ce27 (patch)
treefb916689439d10e29c55abc4e0af24e38ec203ec /drivers/tty/tty_ioctl.c
parent136d5258b2bc4ffae99cb69874a76624c26fbfad (diff)
downloadlinux-c274f6ef1c6665632767d32e4ab912aad839ce27.tar.xz
tty: Hold termios_rwsem for tcflow(TCIxxx)
While transmitting a START/STOP char for tcflow(TCION/TCIOFF), prevent a termios change. Otherwise, a garbage in-band flow control char may be sent, if the termios change overlaps the transmission setup. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/tty_ioctl.c')
-rw-r--r--drivers/tty/tty_ioctl.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index ad9120d1c0f1..62380ccf70fb 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -1164,17 +1164,21 @@ int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
spin_unlock_irq(&tty->flow_lock);
break;
case TCIOFF:
+ down_read(&tty->termios_rwsem);
if (STOP_CHAR(tty) != __DISABLED_CHAR)
- return tty_send_xchar(tty, STOP_CHAR(tty));
+ retval = tty_send_xchar(tty, STOP_CHAR(tty));
+ up_read(&tty->termios_rwsem);
break;
case TCION:
+ down_read(&tty->termios_rwsem);
if (START_CHAR(tty) != __DISABLED_CHAR)
- return tty_send_xchar(tty, START_CHAR(tty));
+ retval = tty_send_xchar(tty, START_CHAR(tty));
+ up_read(&tty->termios_rwsem);
break;
default:
return -EINVAL;
}
- return 0;
+ return retval;
case TCFLSH:
retval = tty_check_change(tty);
if (retval)