[PATCH 5.11 278/601] tty: fix return value for unsupported termiox ioctls

Greg Kroah-Hartman
2021-05-12T17:22:17Z

From: Johan Hovold <johan@kernel.org>

[ Upstream commit 8871de06ff78e9333d86c87d7071452b690e7c9b ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/tty_ioctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 4de1c6ddb8ff..803da2d111c8 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -774,8 +774,8 @@ 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,
--
2.30.2