[PATCH 3.11 106/121] vt: Fix secure clear screen

[Luis Henriques]

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

------------------

From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <petr.pisar at atlas.cz>

commit 0930b0950a8996aa88b0d2ba4bb2bab27cc36bc7 upstream.

\E[3J console code (secure clear screen) needs to update_screen(vc)
in order to write-through blanks into off-screen video memory.

This has been removed accidentally in 3.6 by:

commit 81732c3b2fede049a692e58a7ceabb6d18ffb18c
Author: Jean-François Moine <moinejf at free.fr>
Date:   Thu Sep 6 19:24:13 2012 +0200

    tty vt: Fix line garbage in virtual console on command line edition

Signed-off-by: Petr Písař <petr.pisar at atlas.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/tty/vt/vt.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index c677829..7a35647 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1164,6 +1164,8 @@ static void csi_J(struct vc_data *vc, int vpar)
 			scr_memsetw(vc->vc_screenbuf, vc->vc_video_erase_char,
 				    vc->vc_screenbuf_size >> 1);
 			set_origin(vc);
+			if (CON_IS_VISIBLE(vc))
+				update_screen(vc);
 			/* fall through */
 		case 2: /* erase whole display */
 			count = vc->vc_cols * vc->vc_rows;
-- 
1.9.0