Re: [Xen-devel] [PATCH] libxc: check for null size file mapping

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Feb 12, 2018 at 01:09:15PM +0100, Paul Semel wrote:
> Changed the error message when trying to map a null size file.
> When doing `xl create` command, we get an Invalid Kernel error
> when the file size is greater than zero. For zero length files, we are
> falling in the mmap error, and we get an `Invalid parameter` error,
> which is not explicit. With this change, we get a `zero length file`
> error.
> 
> Signed-off-by: Paul Semel <semelpaul@xxxxxxxxx>

Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>

This can in fact be done right after lseek, but I don't think it is
important enough to ask you to rewrite your patch. :-)

> ---
>  tools/libxc/xc_dom_core.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c
> index 96e71dd2d9..9bd04cb2d5 100644
> --- a/tools/libxc/xc_dom_core.c
> +++ b/tools/libxc/xc_dom_core.c
> @@ -225,6 +225,12 @@ void *xc_dom_malloc_filemap(struct xc_dom_image *dom,
>                       "tried to map file which is too large");
>          goto err;
>      }
> +    else if ( !*size )
> +    {
> +        xc_dom_panic(dom->xch, XC_INTERNAL_ERROR,
> +                     "'%s': zero length file", filename);
> +        goto err;
> +    }
>  
>      block = malloc(sizeof(*block));
>      if ( block == NULL ) {
> -- 
> 2.16.1
> 

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