Re: [Qemu-devel] [PATCH v2] vmdk: return ERROR when cluster sector is larger than vmdk limitation

[Fam Zheng <famz@redhat.com>]

On Thu, 03/22 14:24, yuchenlin@synology.com wrote:
> From: yuchenlin <yuchenlin@synology.com>
> 
> VMDK has a hard limitation of extent size, which is due to the size of grain
> table entry is 32 bits. It means it can only point to a grain located at
> offset = 2^32. To avoid writing the user data beyond limitation and record a useless offset
> in grain table. We should return ERROR here.
> 
> Signed-off-by: yuchenlin <yuchenlin@synology.com>
> ---
> v1->v2:
>  - change commit message
>  - check before allocating
>  - should be >=
>  - the unit is sector now
> 
>  thanks
> 
>  block/vmdk.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index f94c49a9c0..a1c21dbbba 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -47,6 +47,8 @@
>  #define VMDK4_FLAG_MARKER (1 << 17)
>  #define VMDK4_GD_AT_END 0xffffffffffffffffULL
>  
> +#define VMDK_EXTENT_MAX_SECTORS (4294967296)
> +
>  #define VMDK_GTE_ZEROED 0x1
>  
>  /* VMDK internal error codes */
> @@ -1250,6 +1252,10 @@ static int get_cluster_offset(BlockDriverState *bs,
>              return zeroed ? VMDK_ZEROED : VMDK_UNALLOC;
>          }
>  
> +        if (extent->next_cluster_sector >= VMDK_EXTENT_MAX_SECTORS) {
> +            return VMDK_ERROR;
> +        }
> +
>          cluster_sector = extent->next_cluster_sector;
>          extent->next_cluster_sector += extent->cluster_sectors;
>  
> -- 
> 2.16.2
> 

Cc'ing Kevin and Max who merge block/ patches.

Reviewed-by: Fam Zheng <famz@redhat.com>