From patchwork Mon Apr 15 08:22:40 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 236529 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 336942C008E for ; Mon, 15 Apr 2013 18:27:59 +1000 (EST) Received: from localhost ([::1]:60515 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1URelZ-0006st-Cm for incoming@patchwork.ozlabs.org; Mon, 15 Apr 2013 04:27:57 -0400 Received: from eggs.gnu.org ([208.118.235.92]:46910) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1URegr-0008On-J9 for qemu-devel@nongnu.org; Mon, 15 Apr 2013 04:23:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1URego-0007nB-QN for qemu-devel@nongnu.org; Mon, 15 Apr 2013 04:23:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3872) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1URego-0007mp-Ia for qemu-devel@nongnu.org; Mon, 15 Apr 2013 04:23:02 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r3F8N1dO022632 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 15 Apr 2013 04:23:02 -0400 Received: from localhost (ovpn-112-19.ams2.redhat.com [10.36.112.19]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r3F8N0sk023059; Mon, 15 Apr 2013 04:23:01 -0400 From: Stefan Hajnoczi To: Date: Mon, 15 Apr 2013 10:22:40 +0200 Message-Id: <1366014164-17557-8-git-send-email-stefanha@redhat.com> In-Reply-To: <1366014164-17557-1-git-send-email-stefanha@redhat.com> References: <1366014164-17557-1-git-send-email-stefanha@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 209.132.183.28 Cc: Anthony Liguori Subject: [Qemu-devel] [PATCH 07/11] ide: refuse WIN_READ_NATIVE_MAX on empty device X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org What is the highest addressable sector on an empty CD-ROM? Nothing is addressable so produce an error. This patch prevents a divide-by-zero in ide_set_sector() since s->sectors and s->heads would be 0. Not to mention that a sector=-1 argument would be nonsense. Note that WIN_READ_NATIVE_MAX can be triggered using hdparm -N 1024 /dev/cdrom. The LBA bit will be set to 1 though, so the only easy way to go down the ide_set_sector() CHS code path which divides by zero is to comment out the s->select & 0x40 case for testing. Signed-off-by: Stefan Hajnoczi Reviewed-by: Markus Armbruster --- hw/ide/core.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/ide/core.c b/hw/ide/core.c index 87d67b7..c7a8041 100644 --- a/hw/ide/core.c +++ b/hw/ide/core.c @@ -1262,6 +1262,10 @@ void ide_exec_cmd(IDEBus *bus, uint32_t val) lba48 = 1; /* fall through */ case WIN_READ_NATIVE_MAX: + /* Refuse if no sectors are addressable (e.g. medium not inserted) */ + if (s->nb_sectors == 0) { + goto abort_cmd; + } ide_cmd_lba48_transform(s, lba48); ide_set_sector(s, s->nb_sectors - 1); s->status = READY_STAT | SEEK_STAT;