Re: [PATCH 1/5] tools/python: handle libxl__physmap_info.name properly in convert-legacy-stream

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Mon, Jul 05, 2021 at 08:10:23PM +0100, Andrew Cooper wrote:
> From: Olaf Hering <olaf@xxxxxxxxx>
> 
> The trailing member name[] in libxl__physmap_info is written as a
> cstring into the stream. The current code does a sanity check if the
> last byte is zero. This attempt fails with python3 because name[-1]
> returns a type int. As a result the comparison with byte(\00) fails:
> 
>   File "/usr/lib/xen/bin/convert-legacy-stream", line 347, in 
> read_libxl_toolstack
>     raise StreamError("physmap name not NUL terminated")
>   StreamError: physmap name not NUL terminated
> 
> To handle both python variants, cast to bytearray().
> 
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Acked-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>

> ---
>  tools/python/scripts/convert-legacy-stream | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/python/scripts/convert-legacy-stream 
> b/tools/python/scripts/convert-legacy-stream
> index 66ee3d2f5d29..227e1b5c3fd3 100755
> --- a/tools/python/scripts/convert-legacy-stream
> +++ b/tools/python/scripts/convert-legacy-stream
> @@ -343,7 +343,7 @@ def read_libxl_toolstack(vm, data):
>          if twidth == 64:
>              name = name[:-4]
>  
> -        if name[-1] != b'\x00':
> +        if bytearray(name)[-1] != 0:
>              raise StreamError("physmap name not NUL terminated")
>  
>          root = b"physmap/%x" % (phys, )
> -- 
> 2.11.0
> 

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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