Re: [Qemu-devel] [PATCH] virtio-blk: refuse SG_IO requests with scsi=off

[Paolo Bonzini <pbonzini@redhat.com>]

On 01/05/2012 11:05 AM, Paolo Bonzini wrote:
> On 12/23/2011 03:39 PM, 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<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.
>
> Ping.

Ping^2

Paolo