Re: [Qemu-devel] [PATCH] spapr-vscsi: Adding VSCSI capabilities

[Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>]

Benjamin Herrenschmidt <benh@kernel.crashing.org> writes:

> On Mon, 2013-08-26 at 10:02 +0530, Nikunj A Dadhania wrote:
>
>> 
>> From: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
>> 
>> This implements capabilities exchange between host and client.
>> As at the moment no capability is supported, put zero flags everywhere
>> and return.
>> 
>> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
>> ---
>>  hw/scsi/spapr_vscsi.c | 37 +++++++++++++++++++++++++++++++++++++
>>  1 file changed, 37 insertions(+)
>> 
>> diff --git a/hw/scsi/spapr_vscsi.c b/hw/scsi/spapr_vscsi.c
>> index e9090e5..fae3644 100644
>> --- a/hw/scsi/spapr_vscsi.c
>> +++ b/hw/scsi/spapr_vscsi.c
>> @@ -858,6 +858,40 @@ static int vscsi_send_adapter_info(VSCSIState *s, vscsi_req *req)
>>      return vscsi_send_iu(s, req, sizeof(*sinfo), VIOSRP_MAD_FORMAT);
>>  }
>>  
>> +static int vscsi_send_capabilities(VSCSIState *s, vscsi_req *req)
>> +{
>> +    struct viosrp_capabilities *vcap;
>> +    struct capabilities cap;
>> +    uint16_t len = 0;
>
> The above initialization isn't useful
>
>> +    int rc = true;
>> +
>> +    vcap = &req->iu.mad.capabilities;
>> +    len = be16_to_cpu(vcap->common.length);
>> +    if (len > sizeof(&cap)) {
>                         ^ Ugh ? Why the & here ?

Oops, got that wrong.

>
>> +        fprintf(stderr, "vscsi_send_capabilities: size out of bound !\n");
>> +        goto error_out;
>> +    }
>
> I am not 100% familiar with the protocol, could it be that we should
> just read sizeof(cap) instead of erroring out or is there no way it
> can be correct and have a len too long ?

If the length is incorrect, can we trust whether cap is correct or is of
the type we are expecting?