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 --- 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); }