patch "staging: speakup: fix tty-operation NULL derefs" added to tty-linus

patch "staging: speakup: fix tty-operation NULL derefs" added to tty-linus

[gregkh]

This is a note to let you know that I've just added the patch titled

    staging: speakup: fix tty-operation NULL derefs

to my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


From a1960e0f1639cb1f7a3d94521760fc73091f6640 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Wed, 30 Jan 2019 10:49:34 +0100
Subject: staging: speakup: fix tty-operation NULL derefs

The send_xchar() and tiocmset() tty operations are optional. Add the
missing sanity checks to prevent user-space triggerable NULL-pointer
dereferences.

Fixes: 6b9ad1c742bf ("staging: speakup: add send_xchar, tiocmset and input functionality for tty")
Cc: stable <stable@vger.kernel.org>     # 4.13
Cc: Okash Khawaja <okash.khawaja@gmail.com>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/speakup/spk_ttyio.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/speakup/spk_ttyio.c b/drivers/staging/speakup/spk_ttyio.c
index c92bbd05516e..005de0024dd4 100644
--- a/drivers/staging/speakup/spk_ttyio.c
+++ b/drivers/staging/speakup/spk_ttyio.c
@@ -265,7 +265,8 @@ static void spk_ttyio_send_xchar(char ch)
 		return;
 	}
 
-	speakup_tty->ops->send_xchar(speakup_tty, ch);
+	if (speakup_tty->ops->send_xchar)
+		speakup_tty->ops->send_xchar(speakup_tty, ch);
 	mutex_unlock(&speakup_tty_mutex);
 }
 
@@ -277,7 +278,8 @@ static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear)
 		return;
 	}
 
-	speakup_tty->ops->tiocmset(speakup_tty, set, clear);
+	if (speakup_tty->ops->tiocmset)
+		speakup_tty->ops->tiocmset(speakup_tty, set, clear);
 	mutex_unlock(&speakup_tty_mutex);
 }
 
-- 
2.20.1