[Qemu-devel] Re: [PATCH] scsi-disk: add data direction checking

[Hannes Reinecke <hare@suse.de>]

On 11/23/2010 11:03 AM, Stefan Hajnoczi wrote:
> On Mon, Nov 22, 2010 at 10:15 AM, Hannes Reinecke <hare@suse.de> wrote:
>> @@ -172,6 +170,9 @@ static void scsi_read_data(SCSIRequest *req)
>>     /* No data transfer may already be in progress */
>>     assert(r->req.aiocb == NULL);
>>
>> +    if (r->req.cmd.mode == SCSI_XFER_TO_DEV)
>> +        BADF("Data transfer direction invalid\n");
>> +
>>     if (r->sector_count == (uint32_t)-1) {
>>         DPRINTF("Read buf_len=%zd\n", r->iov[0].iov_len);
>>         r->sector_count = 0;
>> @@ -284,6 +285,9 @@ static int scsi_write_data(SCSIRequest *req)
>>     /* No data transfer may already be in progress */
>>     assert(r->req.aiocb == NULL);
>>
>> +    if (r->req.cmd.mode != SCSI_XFER_TO_DEV)
>> +        BADF("Data transfer direction invalid\n");
>> +
>>     n = iov_size(r->iov, r->iov_num) / 512;
>>     if (n) {
>>         qemu_iovec_init_external(&r->qiov, r->iov, r->iov_num);
> 
> If the guest can trigger this then there must be a SCSI response (an
> error?).  Right now BADF() will do fprintf(stderr) and then continue
> executing.
> 
> Can we abort the operation?
> 
I've done a patch for it as per suggestion by hch.
Right now we have

    if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
        DPRINTF("Data transfer direction invalid\n");
        scsi_read_complete(r, -EINVAL);
        return;
    }

and -EINVAL will return the sense code 'INVALID FIELD IN CDB'.
Will be in the next patchset.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)