From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758113AbcBDRt6 (ORCPT ); Thu, 4 Feb 2016 12:49:58 -0500 Received: from mail-pf0-f176.google.com ([209.85.192.176]:35998 "EHLO mail-pf0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757948AbcBDRty (ORCPT ); Thu, 4 Feb 2016 12:49:54 -0500 Subject: Re: [PATCH] tty: use __GFP_NOWARN for user-controlled kmalloc() To: Dmitry Vyukov References: <1454601331-128911-1-git-send-email-dvyukov@google.com> Cc: jslaby@suse.com, gnomes@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org, syzkaller@googlegroups.com, kcc@google.com, glider@google.com From: Peter Hurley Message-ID: <56B38F3F.40706@hurleysoftware.com> Date: Thu, 4 Feb 2016 09:49:51 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <1454601331-128911-1-git-send-email-dvyukov@google.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dmitry, Just a quick procedural note: tty patches need to be addressed to Greg. On 02/04/2016 07:55 AM, Dmitry Vyukov wrote: > Size of kmalloc() in vc_do_resize() is controlled by user. > Too large kmalloc() size triggers WARNING message on console. > > Use __GFP_NOWARN for this kmalloc() to not scare admins. > > Signed-off-by: Dmitry Vyukov > --- > Example WARNING: > > WARNING: CPU: 3 PID: 7642 at mm/page_alloc.c:2999 > __alloc_pages_nodemask+0x7d2/0x1760() > Modules linked in: > CPU: 3 PID: 7642 Comm: a.out Not tainted 4.4.0+ #276 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > 00000000ffffffff ffff88006d24f610 ffffffff82999e2d 0000000000000000 > ffff880060d9af80 ffffffff86475560 ffff88006d24f650 ffffffff81352089 > ffffffff816721e2 ffffffff86475560 0000000000000bb7 00000000024240c0 > Call Trace: > [< inline >] __dump_stack lib/dump_stack.c:15 > [] dump_stack+0x6f/0xa2 lib/dump_stack.c:50 > [] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482 > [] warn_slowpath_null+0x29/0x30 kernel/panic.c:515 > [< inline >] __alloc_pages_slowpath mm/page_alloc.c:2999 > [] __alloc_pages_nodemask+0x7d2/0x1760 mm/page_alloc.c:3253 > [] alloc_pages_current+0xe9/0x450 mm/mempolicy.c:2090 > [< inline >] alloc_pages include/linux/gfp.h:459 > [] alloc_kmem_pages+0x16/0x100 mm/page_alloc.c:3433 > [] kmalloc_order+0x1f/0x80 mm/slab_common.c:1008 > [] kmalloc_order_trace+0x1f/0x140 mm/slab_common.c:1019 > [< inline >] kmalloc_large include/linux/slab.h:395 > [] __kmalloc+0x2f4/0x340 mm/slub.c:3557 > [< inline >] kmalloc include/linux/slab.h:468 > [] vc_do_resize+0x2c0/0x1140 drivers/tty/vt/vt.c:874 > [] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:993 > [< inline >] tiocswinsz drivers/tty/tty_io.c:2357 > [] tty_ioctl+0x1083/0x2160 drivers/tty/tty_io.c:2869 > [< inline >] vfs_ioctl fs/ioctl.c:43 > [] do_vfs_ioctl+0x18c/0xfb0 fs/ioctl.c:674 > [< inline >] SYSC_ioctl fs/ioctl.c:689 > [] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:680 > --- > drivers/tty/vt/vt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c > index bd51bdd..2382810 100644 > --- a/drivers/tty/vt/vt.c > +++ b/drivers/tty/vt/vt.c > @@ -871,7 +871,7 @@ 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; > > - newscreen = kmalloc(new_screen_size, GFP_USER); > + newscreen = kmalloc(new_screen_size, GFP_USER | __GFP_NOWARN); > if (!newscreen) > return -ENOMEM; > >