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Re: [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off |
Date: |
Fri, 13 Jan 2012 10:54:57 -0600 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.23) Gecko/20110922 Lightning/1.0b2 Thunderbird/3.1.15 |
On 12/23/2011 08:39 AM, Paolo Bonzini wrote:
QEMU does have a "scsi" option (to be used like -device
virtio-blk-pci,drive=foo,scsi=off). However, it only
masks the feature bit, and does not reject the command
if a malicious guest disregards the feature bits and
issues a request.
Without this patch, using scsi=off does not protect you
from CVE-2011-4127.
Signed-off-by: Paolo Bonzini<address@hidden>
Applied. Thanks.
Regards,
Anthony Liguori
---
hw/virtio-blk.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index b70d116..6cd3164 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -153,6 +153,12 @@ static void virtio_blk_handle_scsi(VirtIOBlockReq *req)
int status;
int i;
+ if ((req->dev->vdev.guest_features& (1<< VIRTIO_BLK_F_SCSI)) == 0) {
+ virtio_blk_req_complete(req, VIRTIO_BLK_S_UNSUPP);
+ g_free(req);
+ return;
+ }
+
/*
* We require at least one output segment each for the virtio_blk_outhdr
* and the SCSI command block.