Re: [PATCH v2 07/10] qcow2-refcount: check_refcounts_l2(): check reserved bits

[Kirill Tkhai]

On 05.05.2021 09:59, Vladimir Sementsov-Ogievskiy wrote:
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> ---
>  block/qcow2.h          |  1 +
>  block/qcow2-refcount.c | 12 +++++++++++-
>  2 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/block/qcow2.h b/block/qcow2.h
> index c0e1e83796..b8b1093b61 100644
> --- a/block/qcow2.h
> +++ b/block/qcow2.h
> @@ -587,6 +587,7 @@ typedef enum QCow2MetadataOverlap {
>  
>  #define L1E_OFFSET_MASK 0x00fffffffffffe00ULL
>  #define L2E_OFFSET_MASK 0x00fffffffffffe00ULL
> +#define L2E_STD_RESERVED_MASK 0x3f000000000001feULL
>  
>  #define REFT_OFFSET_MASK 0xfffffffffffffe00ULL
>  
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index 062ec48a15..47cc82449b 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -1682,8 +1682,18 @@ static int check_refcounts_l2(BlockDriverState *bs, 
> BdrvCheckResult *res,
>          int csize;
>          l2_entry = get_l2_entry(s, l2_table, i);
>          uint64_t l2_bitmap = get_l2_bitmap(s, l2_table, i);
> +        QCow2ClusterType type = qcow2_get_cluster_type(bs, l2_entry);
>  
> -        switch (qcow2_get_cluster_type(bs, l2_entry)) {
> +        if (type != QCOW2_CLUSTER_COMPRESSED) {
> +            /* Check reserved bits of Standard Cluster Descriptor */
> +            if (l2_entry & L2E_STD_RESERVED_MASK) {
> +                fprintf(stderr, "ERROR found l2 entry with reserved bits 
> set: "
> +                        "%" PRIx64, l2_entry);

'\n' is missed.

The rest is OK for me.

Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>

> +                res->corruptions++;
> +            }
> +        }
> +
> +        switch (type) {
>          case QCOW2_CLUSTER_COMPRESSED:
>              /* Compressed clusters don't have QCOW_OFLAG_COPIED */
>              if (l2_entry & QCOW_OFLAG_COPIED) {
>