Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754700Ab0BSRPj (ORCPT ); Fri, 19 Feb 2010 12:15:39 -0500 Received: from kroah.org ([198.145.64.141]:57427 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754510Ab0BSRAW (ORCPT ); Fri, 19 Feb 2010 12:00:22 -0500 X-Mailbox-Line: From gregkh@kvm.kroah.org Fri Feb 19 08:32:36 2010 Message-Id: <20100219163236.615628112@kvm.kroah.org> User-Agent: quilt/0.48-4.4 Date: Fri, 19 Feb 2010 08:29:16 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jody Bruchon , Takashi Iwai Subject: [23/93] ALSA: hda-intel: Avoid divide by zero crash In-Reply-To: <20100219165717.GA15002@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1651 Lines: 48 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: Jody Bruchon commit fed08d036f2aabd8d0c684439de37f8ebec2bbc2 upstream. On my AMD780V chipset, hda_intel.c can crash the kernel with a divide by zero for as-yet unknown reasons. A simple check for zero prevents it, though the problem that causes it remains. Since the workaround is harmless and won't affect anyone except victims of this bug, it should be safe; moreover, because this crash can be triggered by a user-mode application, there are denial of service implications on the systems affected by the bug without the patch. Signed-off-by: Jody Bruchon Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/pci/hda/hda_intel.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -1858,6 +1858,12 @@ static int azx_position_ok(struct azx *c if (!bdl_pos_adj[chip->dev_index]) return 1; /* no delayed ack */ + if (azx_dev->period_bytes == 0) { + printk(KERN_WARNING + "hda-intel: Divide by zero was avoided " + "in azx_dev->period_bytes.\n"); + return 0; + } if (pos % azx_dev->period_bytes > azx_dev->period_bytes / 2) return 0; /* NG - it's below the period boundary */ return 1; /* OK, it's fine */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/