[Devel] [PATCH vz7 v2 2/4] tty: limit terminal size to 4M chars

[Oleg Babin]

From: Dmitry Vyukov <dvyukov at google.com>

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
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 fbc6290..b49abe5 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;
-- 
1.8.3.1