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From: Paolo Bonzini <pbonzini@redhat.com>

To: qemu-stable@nongnu.org

Date: Wed, 11 Jan 2012 10:48:33 +0100

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Subject: [Qemu-stable] [PATCH] virtio-blk: refuse SG_IO requests with

	scsi=off

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Status: RO

Content-Length: 1003

Lines: 38

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 <pbonzini@redhat.com>

---

 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.

-- 

1.7.7.1