Re: [Qemu-devel] [PATCH for-1.4] tests/test-string-input-visitor: Handle errors provoked by fuzz test

[Andreas Färber]

Am 02.02.2013 22:19, schrieb Peter Maydell:
> It's OK and expected for visitors to return errors when presented with
> the fuzz test's random data. This means the test harness needs to
> handle them; check for and free any error after each visitor call,
> and only free the string returned by visit_type_str if visit_type_str
> succeeded.
> 
> This fixes a problem where this test failed the MacOSX malloc()
> consistency checks and might segfault on other platforms [due
> to calling free() on an uninitialized pointer variable].
> 
> Signed-off-by: Peter Maydell <address@hidden>
> ---
>  tests/test-string-input-visitor.c | 23 ++++++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/test-string-input-visitor.c 
> b/tests/test-string-input-visitor.c
> index f6b0093..793b334 100644
> --- a/tests/test-string-input-visitor.c
> +++ b/tests/test-string-input-visitor.c
> @@ -194,20 +194,41 @@ static void test_visitor_in_fuzz(TestInputVisitorData 
> *data,
>  
>          v = visitor_input_test_init(data, buf);
>          visit_type_int(v, &ires, NULL, &errp);
> +        if (error_is_set(&errp)) {
> +            error_free(errp);
> +            errp = NULL;
> +        }

It seems to me the naming is bad here: errp appears to be an Error*, not
an Error**. It would be nice to fix this within the function touched.

Since it is an Error*, I think it was said that we should not use
error_is_set() but err != NULL (or if you prefer, just err).
error_is_set() is intended for **errp arguments that may be NULL.

Your analysis and the freeing and NULL'ing as solution looks correct.

Andreas

>  
>          v = visitor_input_test_init(data, buf);
>          visit_type_bool(v, &bres, NULL, &errp);
> +        if (error_is_set(&errp)) {
> +            error_free(errp);
> +            errp = NULL;
> +        }
>          visitor_input_teardown(data, NULL);
>  
>          v = visitor_input_test_init(data, buf);
>          visit_type_number(v, &nres, NULL, &errp);
> +        if (error_is_set(&errp)) {
> +            error_free(errp);
> +            errp = NULL;
> +        }
>  
>          v = visitor_input_test_init(data, buf);
>          visit_type_str(v, &sres, NULL, &errp);
> -        g_free(sres);
> +        if (error_is_set(&errp)) {
> +            error_free(errp);
> +            errp = NULL;
> +        } else {
> +            g_free(sres);
> +        }
>  
>          v = visitor_input_test_init(data, buf);
>          visit_type_EnumOne(v, &eres, NULL, &errp);
> +        if (error_is_set(&errp)) {
> +            error_free(errp);
> +            errp = NULL;
> +        }
>          visitor_input_teardown(data, NULL);
>      }
>  }
> 


-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg