Hi Sebastian,

> On 12.09.2016, at 20:09, Sebastian Ott <seb...@linux.vnet.ibm.com> wrote:
> 
> 
> Genwqe uses dma_alloc_coherent and depends on zero initialized memory. On
> one occasion it ueses an explicit memset on others it uses un-initialized
> memory.
> 
> This bug was covered because some archs actually return zero initialized
> memory when using dma_alloc_coherent but this is by no means guaranteed.
> Simply switch to dma_zalloc_coherent.

Thanks for figuring this out. I hope you found all spots where this 
misassumption is done.

> 
> Signed-off-by: Sebastian Ott <seb...@linux.vnet.ibm.com>
> ---
> drivers/misc/genwqe/card_ddcb.c  | 2 --
> drivers/misc/genwqe/card_utils.c | 4 ++--
> 2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/misc/genwqe/card_ddcb.c b/drivers/misc/genwqe/card_ddcb.c
> index 353ee0c..ddfeefe 100644
> --- a/drivers/misc/genwqe/card_ddcb.c
> +++ b/drivers/misc/genwqe/card_ddcb.c
> @@ -1048,8 +1048,6 @@ static int setup_ddcb_queue(struct genwqe_dev *cd, 
> struct ddcb_queue *queue)
>                       "[%s] **err: could not allocate DDCB **\n", __func__);
>               return -ENOMEM;
>       }
> -     memset(queue->ddcb_vaddr, 0, queue_size);
> -
>       queue->ddcb_req = kzalloc(sizeof(struct ddcb_requ *) *
>                                 queue->ddcb_max, GFP_KERNEL);
>       if (!queue->ddcb_req) {
> diff --git a/drivers/misc/genwqe/card_utils.c 
> b/drivers/misc/genwqe/card_utils.c
> index 222367c..8a679ec 100644
> --- a/drivers/misc/genwqe/card_utils.c
> +++ b/drivers/misc/genwqe/card_utils.c
> @@ -220,8 +220,8 @@ void *__genwqe_alloc_consistent(struct genwqe_dev *cd, 
> size_t size,
>       if (get_order(size) > MAX_ORDER)
>               return NULL;
> 
> -     return dma_alloc_coherent(&cd->pci_dev->dev, size, dma_handle,
> -                               GFP_KERNEL);
> +     return dma_zalloc_coherent(&cd->pci_dev->dev, size, dma_handle,
> +                                GFP_KERNEL);
> }
> 
> void __genwqe_free_consistent(struct genwqe_dev *cd, size_t size,
> -- 
> 2.5.5
> 
I think this should be fine.

Signed-off-by: Frank Haverkamp <ha...@linux.vnet.ibm.com>

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