From: Peter Hurley Date: Wed, 10 Sep 2014 19:06:35 +0000 (-0400) Subject: tty: Hold termios_rwsem for tcflow(TCIxxx) X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c274f6ef1c6665632767d32e4ab912aad839ce27;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git 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 Signed-off-by: Greg Kroah-Hartman --- 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)