From mboxrd@z Thu Jan 1 00:00:00 1970 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 From: Stefan Hajnoczi 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> Subject: [Qemu-devel] [PATCH 07/11] 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: Anthony Liguori 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; -- 1.8.1.4