[PATCH 3.10 213/319] tty: limit terminal size to 4M chars

Willy Tarreau
2017-02-05T20:02:54Z

From: Dmitry Vyukov <dvyukov@google.com>

commit 32b2921e6a7461fe63b71217067a6cf4bddb132f upstream.

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@google.com>
CC: David Rientjes <rientjes@google.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: linux-kernel@vger.kernel.org
Cc: syzkaller@googlegroups.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
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 6dff194..ee51acd 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -863,6 +863,8 @@ 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;
--
2.8.0.rc2.1.gbe9624a