Re: [Xen-devel] [PATCH 06/29] libxc: don't read uninitialized size value in xc_read_image

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-10-30 at 20:51 +1300, Matthew Daley wrote:
> This error case can only be triggered by gzread returning 0 (and having
> not read anything), so move it there.
> 
> Coverity-ID: 1056076

Is this right? It seems to correspond to an issue in xc_hvm_build --
which doesn't look related. 

> Signed-off-by: Matthew Daley <mattjd@xxxxxxxxx>
> ---
>  tools/libxc/xg_private.c |   14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/libxc/xg_private.c b/tools/libxc/xg_private.c
> index 8fa068e..a914068 100644
> --- a/tools/libxc/xg_private.c
> +++ b/tools/libxc/xg_private.c
> @@ -71,6 +71,12 @@ char *xc_read_image(xc_interface *xch,
>              image = NULL;
>              goto out;
>          case 0: /* EOF */
> +            if ( *size == 0 )
> +            {
> +                PERROR("Could not read kernel image");
> +                free(image);
> +                image = NULL;
> +            }
>              goto out;
>          default:
>              *size += bytes;
> @@ -80,13 +86,7 @@ char *xc_read_image(xc_interface *xch,
>  #undef CHUNK
>  
>   out:
> -    if ( *size == 0 )
> -    {
> -        PERROR("Could not read kernel image");
> -        free(image);
> -        image = NULL;
> -    }
> -    else if ( image )
> +    if ( image )
>      {
>          /* Shrink allocation to fit image. */
>          tmp = realloc(image, *size);



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