RE: [PATCH 5/7] scsi: storvsc: Fix a bug in copy_from_bounce_buffer()

[Long Li]

> -----Original Message-----
> From: devel [mailto:driverdev-devel-bounces@xxxxxxxxxxxxxxxxxxxxxx] On
> Behalf Of K. Y. Srinivasan
> Sent: Monday, March 23, 2015 2:07 PM
> To: gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; ohering@xxxxxxxx; jbottomley@xxxxxxxxxxxxx;
> hch@xxxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx; apw@xxxxxxxxxxxxx;
> vkuznets@xxxxxxxxxx; jasowang@xxxxxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx
> Subject: [PATCH 5/7] scsi: storvsc: Fix a bug in copy_from_bounce_buffer()
> 
> We may exit this function without properly freeing up the maapings we may
> have acquired. Fix the bug.
> 
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
Reviewed-by: Long Li <longli@xxxxxxxxxxxxx>

> Cc: <stable@xxxxxxxxxxxxxxx>
> ---
>  drivers/scsi/storvsc_drv.c |   15 ++++++++-------
>  1 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index
> 5c13eec..88f5d79 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -754,21 +754,22 @@ static unsigned int copy_to_bounce_buffer(struct
> scatterlist *orig_sgl,
>  			if (bounce_sgl[j].length == PAGE_SIZE) {
>  				/* full..move to next entry */
>  				sg_kunmap_atomic(bounce_addr);
> +				bounce_addr = 0;
>  				j++;
> +			}
> 
> -				/* if we need to use another bounce buffer */
> -				if (srclen || i != orig_sgl_count - 1)
> -					bounce_addr =
> sg_kmap_atomic(bounce_sgl,j);
> +			/* if we need to use another bounce buffer */
> +			if (srclen && bounce_addr == 0)
> +				bounce_addr = sg_kmap_atomic(bounce_sgl,
> j);
> 
> -			} else if (srclen == 0 && i == orig_sgl_count - 1) {
> -				/* unmap the last bounce that is < PAGE_SIZE
> */
> -				sg_kunmap_atomic(bounce_addr);
> -			}
>  		}
> 
>  		sg_kunmap_atomic(src_addr - orig_sgl[i].offset);
>  	}
> 
> +	if (bounce_addr)
> +		sg_kunmap_atomic(bounce_addr);
> +
>  	local_irq_restore(flags);
> 
>  	return total_copied;
> --
> 1.7.4.1
> 
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