From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:39992) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UO3If-0008GD-Hq for qemu-devel@nongnu.org; Fri, 05 Apr 2013 05:51:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UO3IZ-0006bp-F6 for qemu-devel@nongnu.org; Fri, 05 Apr 2013 05:51:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25451) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UO3IZ-0006bj-81 for qemu-devel@nongnu.org; Fri, 05 Apr 2013 05:51:07 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r359p6Nx025858 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 5 Apr 2013 05:51:06 -0400 From: Stefan Hajnoczi Date: Fri, 5 Apr 2013 11:51:01 +0200 Message-Id: <1365155461-11072-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH] ide: refuse WIN_READ_NATIVE_MAX on empty device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , Markus Armbruster , Stefan Hajnoczi 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 --- hw/ide/core.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/hw/ide/core.c b/hw/ide/core.c index 3743dc3..77f1379 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; -- 1.8.1.4