[PATCH 4.2.y-ckt 022/218] tty: Fix GPF in flush_to_ldisc(), part 2

From: Kamal Mostafa
Date: Thu Mar 31 2016 - 17:22:27 EST

4.2.8-ckt7 -stable review patch. If anyone has any objections, please let me know.


From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>

commit f33798deecbd59a2955f40ac0ae2bc7dff54c069 upstream.

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

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().

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
include/linux/tty.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/tty.h b/include/linux/tty.h
index 342a760..245524a2 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -592,7 +592,7 @@ 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;