File 0080-virtio-scsi-fix-buffer-overrun-on-i.patch of Package qemu-linux-user

Overview Repositories Revisions Requests Users Attributes Meta

File 0080-virtio-scsi-fix-buffer-overrun-on-i.patch of Package qemu-linux-user

From e39d190505f3cdbbc0cde9d079b7f9b7a7fe40cb Mon Sep 17 00:00:00 2001
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Thu, 3 Apr 2014 19:52:17 +0300
Subject: [PATCH] virtio-scsi: fix buffer overrun on invalid state load
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

CVE-2013-4542

hw/scsi/scsi-bus.c invokes load_request.

virtio_scsi_load_request does:
    qemu_get_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem));

this probably can make elem invalid, for example,
make in_num or out_num huge, then:

virtio_scsi_parse_req(s, vs->cmd_vqs[n], req);

will do:

if (req->elem.out_num > 1) {
        qemu_sgl_init_external(req, &req->elem.out_sg[1],
                               &req->elem.out_addr[1],
                               req->elem.out_num - 1);
    } else {
        qemu_sgl_init_external(req, &req->elem.in_sg[1],
                               &req->elem.in_addr[1],
                               req->elem.in_num - 1);
    }

and this will access out of array bounds.

Note: this adds security checks within assert calls since
SCSIBusInfo's load_request cannot fail.
For now simply disable builds with NDEBUG - there seems
to be little value in supporting these.

Cc: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
(cherry picked from commit 3c3ce981423e0d6c18af82ee62f1850c2cda5976)
[AF: BNC#864804]
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 hw/scsi/virtio-scsi.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index b0d7517..1752193 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -147,6 +147,15 @@ static void *virtio_scsi_load_request(QEMUFile *f, SCSIRequest *sreq)
     qemu_get_be32s(f, &n);
     assert(n < vs->conf.num_queues);
     qemu_get_buffer(f, (unsigned char *)&req->elem, sizeof(req->elem));
+    /* TODO: add a way for SCSIBusInfo's load_request to fail,
+     * and fail migration instead of asserting here.
+     * When we do, we might be able to re-enable NDEBUG below.
+     */
+#ifdef NDEBUG
+#error building with NDEBUG is not supported
+#endif
+    assert(req->elem.in_num <= ARRAY_SIZE(req->elem.in_sg));
+    assert(req->elem.out_num <= ARRAY_SIZE(req->elem.out_sg));
     virtio_scsi_parse_req(s, vs->cmd_vqs[n], req);
 
     scsi_req_ref(sreq);

Places

File 0080-virtio-scsi-fix-buffer-overrun-on-i.patch of Package qemu-linux-user

Places