From 0145b4c38110d36d4ce9f1659a93a6f0859a0ff7 Mon Sep 17 00:00:00 2001
From: Michael S. Tsirkin <mst@redhat.com>
Date: Sun, 11 May 2014 16:21:54 -0500
Subject: [PATCH 13/20] virtio-scsi: fix buffer overrun on invalid state load
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RH-Author: Michael S. Tsirkin <mst@redhat.com>
Message-id: <1399825266-9366-1-git-send-email-mst@redhat.com>
Patchwork-id: 58791
O-Subject: [PATCH qemu-kvm RHEL6.6] virtio-scsi: fix buffer overrun on invalid state load
Bugzilla: 1096097
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Juan Quintela <quintela@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
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)
Bugzilla: 1096097
Tested: lightly on developer's box
Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7440378
---
Note: same as 6.5.z backport
hw/virtio-scsi.c | 9 +++++++++
1 file changed, 9 insertions(+)
Signed-off-by: Jeff E. Nelson <jen@redhat.com>
---
hw/virtio-scsi.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/hw/virtio-scsi.c b/hw/virtio-scsi.c
index cfb9764..b55c355 100644
--- a/hw/virtio-scsi.c
+++ b/hw/virtio-scsi.c
@@ -267,6 +267,15 @@ static void *virtio_scsi_load_request(QEMUFile *f, SCSIRequest *sreq)
qemu_get_be32s(f, &n);
assert(n == 0);
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, s->cmd_vq, req);
scsi_req_ref(sreq);
--
1.7.1