tty: fix return value for unsupported termiox ioctls

Drivers should return -ENOTTY ("Inappropriate I/O control operation")
when an ioctl isn't supported, while -EINVAL is used for invalid
arguments.

Support for termiox was added by commit 1d65b4a088de ("tty: Add
termiox") in 2008 but no driver support ever followed and it was
recently ripped out by commit e0efb3168d34 ("tty: Remove dead termiox
code").

Fix the return value for the unsupported termiox ioctls, which have
always returned -EINVAL, by explicitly returning -ENOTTY rather than
removing them completely and falling back to the default unrecognised-
ioctl handling.

Fixes: 1d65b4a088de ("tty: Add termiox")
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407095208.31838-4-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index deffaef..420e767 100644 (file)
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -773,8 +773,8 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
        case TCSETX:
        case TCSETXW:
        case TCSETXF:
-               return -EINVAL;
-#endif         
+               return -ENOTTY;
+#endif
        case TIOCGSOFTCAR:
                copy_termios(real_tty, &kterm);
                ret = put_user((kterm.c_cflag & CLOCAL) ? 1 : 0,