netdev - Re: [patch net-next] tools: ynl: fix attr_space variable to exist even if processing unknown attribute

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Message-ID: <8bcd540b747ae30edc10c5208d7876b901e702b8.camel@redhat.com>
Date: Thu, 15 Feb 2024 11:59:08 +0100
From: Paolo Abeni <pabeni@...hat.com>
To: Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org
Cc: kuba@...nel.org, davem@...emloft.net, edumazet@...gle.com, 
	donald.hunter@...il.com
Subject: Re: [patch net-next] tools: ynl: fix attr_space variable to exist
 even if processing unknown attribute

On Tue, 2024-02-13 at 08:04 +0100, Jiri Pirko wrote:
> From: Jiri Pirko <jiri@...dia.com>
> 
> If message contains unknown attribute and user passes
> "--process-unknown" command line option, _decode() gets called with space
> arg set to None. In that case, attr_space variable is not initialized
> used which leads to following trace:
> 
> Traceback (most recent call last):
>   File "./tools/net/ynl/cli.py", line 77, in <module>
>     main()
>   File "./tools/net/ynl/cli.py", line 68, in main
>     reply = ynl.dump(args.dump, attrs)
>             ^^^^^^^^^^^^^^^^^^^^^^^^^^
>   File "tools/net/ynl/lib/ynl.py", line 909, in dump
>     return self._op(method, vals, [], dump=True)
>            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>   File "tools/net/ynl/lib/ynl.py", line 894, in _op
>     rsp_msg = self._decode(decoded.raw_attrs, op.attr_set.name)
>               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>   File "tools/net/ynl/lib/ynl.py", line 639, in _decode
>     self._rsp_add(rsp, attr_name, None, self._decode_unknown(attr))
>                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^
>   File "tools/net/ynl/lib/ynl.py", line 569, in _decode_unknown
>     return self._decode(NlAttrs(attr.raw), None)
>            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>   File "tools/net/ynl/lib/ynl.py", line 630, in _decode
>     search_attrs = SpaceAttrs(attr_space, rsp, outer_attrs)
>                               ^^^^^^^^^^
> UnboundLocalError: cannot access local variable 'attr_space' where it is not associated with a value
> 
> Fix this by setting attr_space to None in case space is arg None.
> 
> Fixes: bf8b832374fb ("tools/net/ynl: Support sub-messages in nested attribute spaces")
> Signed-off-by: Jiri Pirko <jiri@...dia.com>
> ---
>  tools/net/ynl/lib/ynl.py | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
> index 03c7ca6aaae9..b16d24b7e288 100644
> --- a/tools/net/ynl/lib/ynl.py
> +++ b/tools/net/ynl/lib/ynl.py
> @@ -588,10 +588,12 @@ class YnlFamily(SpecFamily):
>          revalue = search_attrs.lookup(selector)turn decoded
>  
>      def _decode(self, attrs, space, outer_attrs = None):
> +        rsp = dict()
>          if space:
>              attr_space = self.attr_sets[space]
> -        rsp = dict()
> -        search_attrs = SpaceAttrs(attr_space, rsp, outer_attrs)
> +            search_attrs = SpaceAttrs(attr_space, rsp, outer_attrs)
> +        else:
> +            search_attrs = None

It looks like that later-on the code could call self._decode_sub_msg()
-> self._resolve_selector() with search_attrs == None, and the latter
will unconditionally do:

	value = search_attrs.lookup(selector)

I think we need to explicitly handle the None value there.

Thanks,

Paolo