From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756639AbcBDS2R (ORCPT ); Thu, 4 Feb 2016 13:28:17 -0500 Received: from mail-wm0-f45.google.com ([74.125.82.45]:35370 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755716AbcBDS2P (ORCPT ); Thu, 4 Feb 2016 13:28:15 -0500 From: Dmitry Vyukov To: gregkh@linuxfoundation.org, jslaby@suse.com, peter@hurleysoftware.com, gnomes@lxorguk.ukuu.org.uk Cc: linux-kernel@vger.kernel.org, syzkaller@googlegroups.com, kcc@google.com, glider@google.com, Dmitry Vyukov Subject: [PATCH] tty: use __GFP_NOWARN for user-controlled kmalloc Date: Thu, 4 Feb 2016 19:28:00 +0100 Message-Id: <1454610480-87854-1-git-send-email-dvyukov@google.com> X-Mailer: git-send-email 2.7.0.rc3.207.g0ac5344 In-Reply-To: <56B38F3F.40706@hurleysoftware.com> References: <56B38F3F.40706@hurleysoftware.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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; -- 2.7.0.rc3.207.g0ac5344