Re: [PATCH] vhost/scsi: truncate T10 PI iov_iter to prot_bytes

[Paolo Bonzini <pbonzini@redhat.com>]

On 21/09/2018 19:49, Greg Edwards wrote:
> On Wed, Aug 22, 2018 at 01:21:53PM -0600, Greg Edwards wrote:
>> Commands with protection information included were not truncating the
>> protection iov_iter to the number of protection bytes in the command.
>> This resulted in vhost_scsi mis-calculating the size of the protection
>> SGL in vhost_scsi_calc_sgls(), and including both the protection and
>> data SG entries in the protection SGL.
>>
>> Fixes: 09b13fa8c1a1 ("vhost/scsi: Add ANY_LAYOUT support in vhost_scsi_handle_vq")
>> Signed-off-by: Greg Edwards <gedwards@ddn.com>
> 
> 
> Any thoughts on this patch?
> 
> 
>> ---
>>  drivers/vhost/scsi.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
>> index 76f8d649147b..cbe0ea26c1ff 100644
>> --- a/drivers/vhost/scsi.c
>> +++ b/drivers/vhost/scsi.c
>> @@ -964,7 +964,8 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
>>  				prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesin);
>>  			}
>>  			/*
>> -			 * Set prot_iter to data_iter, and advance past any
>> +			 * Set prot_iter to data_iter and truncate it to
>> +			 * prot_bytes, and advance data_iter past any
>>  			 * preceeding prot_bytes that may be present.
>>  			 *
>>  			 * Also fix up the exp_data_len to reflect only the
>> @@ -973,6 +974,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
>>  			if (prot_bytes) {
>>  				exp_data_len -= prot_bytes;
>>  				prot_iter = data_iter;
>> +				iov_iter_truncate(&prot_iter, prot_bytes);
>>  				iov_iter_advance(&data_iter, prot_bytes);
>>  			}
>>  			tag = vhost64_to_cpu(vq, v_req_pi.tag);
>> --
>> 2.17.1

Fixes: 09b13fa8c1a1093e9458549ac8bb203a7c65c62a
Cc: stable@vger.kernel.org
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>