Re: [Qemu-devel] [PATCH v3 4/6] vmdk: Check descriptor file length when reading it

[Max Reitz]

On 2014-12-03 at 11:28, Fam Zheng wrote:
> Since a too small file cannot be a valid VMDK image, and also since the
> buffer's first 4 bytes will be unconditionally examined by
> vmdk_open_sparse, let's error out the small file case to be clear.
>
> Signed-off-by: Fam Zheng <address@hidden>
> Reviewed-by: Markus Armbruster <address@hidden>
> ---
>   block/vmdk.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 82257cd..045fd7a 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -557,6 +557,11 @@ static char *vmdk_read_desc(BlockDriverState *file, 
> uint64_t desc_offset,
>           return NULL;
>       }
>   
> +    if (size < 4) {
> +        error_setg_errno(errp, -size, "File is too small, not a valid image");

0 <= size < 4, strerror(0..-3) doesn't make a whole lot of sense. Should 
be simply error_setg() instead of error_setg_errno().

Max

> +        return NULL;
> +    }
> +
>       size = MIN(size, (1 << 20) - 1);  /* avoid unbounded allocation */
>       buf = g_malloc(size + 1);
>