Re: [PATCH nft] json: fix error protagation when parsing binop lhs/rhs

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Fri, Mar 28, 2025 at 03:49:04PM +0100, Florian Westphal wrote:
> Malformed input returns NULL when decoding left/right side of binop.
> This causes a NULL dereference in expr_evaluate_binop; left/right must
> point to a valid expression.
> 
> Fix this in the parser, else would have to sprinkle NULL checks all over
> the evaluation code.
> 
> After fix, loading the bogon yields:
> internal:0:0-0: Error: Malformed object (too many properties): '{}'.
> internal:0:0-0: Error: could not decode binop rhs, '<<'.
> internal:0:0-0: Error: Invalid mangle statement value
> internal:0:0-0: Error: Parsing expr array at index 1 failed.
> internal:0:0-0: Error: Parsing command array at index 3 failed.
> 
> Fixes: 0ac39384fd9e ("json: Accept more than two operands in binary expressions")
> Signed-off-by: Florian Westphal <fw@strlen.de>

Reviewed-by: Pablo Neira Ayuso <pablo@netfilter.org>

one nitpick:

> diff --git a/tests/shell/testcases/bogons/nft-j-f/binop_rhs_decode_error_crash b/tests/shell/testcases/bogons/nft-j-f/binop_rhs_decode_error_crash
> new file mode 100644
> index 000000000000..c5de17111ff6
> --- /dev/null
> +++ b/tests/shell/testcases/bogons/nft-j-f/binop_rhs_decode_error_crash
[...]
> +              "value": {
> +                "<<": [
> +                  {
> +                    "|": [
> +                      {
> +                        "meta": {
> +                          "key": "mark"
> +                        }
> +                      },
> +                      16
> +                    ]
> +                  },
> +    {  },

Something strange here in this indent.

> +                  8
> +                ]
> +              }
> +            }
> +          }
> +        ]
> +      }
> +    }
> +  ]
> +}