[Devel] [PATCH RHEL7 COMMIT] ms/tty: limit terminal size to 4M chars

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.21.1.vz7.47.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.21.1.vz7.47.6
------>
commit f0e9468c19222f0acc3e264643d43dfefae1d8b6
Author: Dmitry Vyukov <dvyukov at google.com>
Date:   Wed May 16 11:09:24 2018 +0300

    ms/tty: limit terminal size to 4M chars
    
    Size of kmalloc() in vc_do_resize() is controlled by user.
    Too large kmalloc() size triggers WARNING message on console.
    Put a reasonable upper bound on terminal size to prevent WARNINGs.
    
    Signed-off-by: Dmitry Vyukov <dvyukov at google.com>
    CC: David Rientjes <rientjes at google.com>
    Cc: One Thousand Gnomes <gnomes at lxorguk.ukuu.org.uk>
    Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
    Cc: Jiri Slaby <jslaby at suse.com>
    Cc: Peter Hurley <peter at hurleysoftware.com>
    Cc: linux-kernel at vger.kernel.org
    Cc: syzkaller at googlegroups.com
    Cc: stable <stable at vger.kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
    
    ms commit 32b2921e6a7461fe63b71217067a6cf4bddb132f
    
    https://jira.sw.ru/browse/HCI-53
    Signed-off-by: Oleg Babin <obabin at virtuozzo.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 fbc6290e417a..b49abe57b05f 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -871,6 +871,8 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 	if (new_cols == vc->vc_cols && new_rows == vc->vc_rows)
 		return 0;
 
+	if (new_screen_size > (4 << 20))
+		return -EINVAL;
 	newscreen = kmalloc(new_screen_size, GFP_USER);
 	if (!newscreen)
 		return -ENOMEM;