From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35800) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uowic-0008W4-7e for qemu-devel@nongnu.org; Tue, 18 Jun 2013 10:17:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uowia-0001Od-5h for qemu-devel@nongnu.org; Tue, 18 Jun 2013 10:17:10 -0400 Sender: Paolo Bonzini From: Paolo Bonzini Date: Tue, 18 Jun 2013 16:16:51 +0200 Message-Id: <1371565016-2643-3-git-send-email-pbonzini@redhat.com> In-Reply-To: <1371565016-2643-1-git-send-email-pbonzini@redhat.com> References: <1371565016-2643-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 2/7] scsi-generic: fix sign extension of READ CAPACITY(10) data List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: mdroth@linux.vnet.ibm.com, qemu-stable@nongnu.org Issuing the READ CAPACITY(10) command in the guest will cause QEMU to update its knowledge of the maximum accessible LBA in the disk. The recorded maximum LBA will be wrong if the disk is bigger than 1TB, because ldl_be_p returns a signed int. When this is fixed, a latent bug will be unmasked. If the READ CAPACITY(10) command reported an overflow (0xFFFFFFFF), we must not overwrite the previously-known maximum accessible LBA, or the guest will fail to access the disk above the first 2TB. Cc: qemu-stable@nongnu.org Signed-off-by: Paolo Bonzini --- hw/scsi/scsi-generic.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c index 2a9a561..19bd36c 100644 --- a/hw/scsi/scsi-generic.c +++ b/hw/scsi/scsi-generic.c @@ -198,9 +198,10 @@ static void scsi_read_complete(void * opaque, int ret) scsi_command_complete(r, 0); } else { /* Snoop READ CAPACITY output to set the blocksize. */ - if (r->req.cmd.buf[0] == READ_CAPACITY_10) { + if (r->req.cmd.buf[0] == READ_CAPACITY_10 && + (ldl_be_p(&r->buf[0]) != 0xffffffffU || s->max_lba == 0)) { s->blocksize = ldl_be_p(&r->buf[4]); - s->max_lba = ldl_be_p(&r->buf[0]); + s->max_lba = ldl_be_p(&r->buf[0]) & 0xffffffffULL; } else if (r->req.cmd.buf[0] == SERVICE_ACTION_IN_16 && (r->req.cmd.buf[1] & 31) == SAI_READ_CAPACITY_16) { s->blocksize = ldl_be_p(&r->buf[8]); -- 1.8.1.4