tty: Fix GPF in flush_to_ldisc(), part 2

commit 9ce119f318ba ("tty: Fix GPF in flush_to_ldisc()") fixed a
GPF caused by a line discipline which does not define a receive_buf()
method.

However, the vt driver (and speakup driver also) pushes selection
data directly to the line discipline receive_buf() method via
tty_ldisc_receive_buf(). Fix the same problem in tty_ldisc_receive_buf().

Cc: <stable@vger.kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/tty.h b/include/linux/tty.h
index dea7d54d00d42630dfa7ea76a62091a2ba6fbf6f..03e4015fa033f820fb519c5d8b5d9951bca6fd2f 100644 (file)
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -579,7 +579,7 @@ static inline int tty_ldisc_receive_buf(struct tty_ldisc *ld, unsigned char *p,
                count = ld->ops->receive_buf2(ld->tty, p, f, count);
        else {
                count = min_t(int, count, ld->tty->receive_room);
-               if (count)
+               if (count && ld->ops->receive_buf)
                        ld->ops->receive_buf(ld->tty, p, f, count);
        }
        return count;