Re: [Qemu-devel] [PATCH v2 for-1.4] tests/test-string-input-visitor: Handle errors provoked by fuzz test

[Luiz Capitulino]

On Tue,  5 Feb 2013 20:44:23 +0000
Peter Maydell <address@hidden> wrote:

> It's OK and expected for visitors to return errors when presented with
> the fuzz test's random data. Since the fuzzer doesn't care about
> errors, we pass in NULL rather than an Error**. This fixes a bug in
> the fuzzer where it was passing the same Error** into each visitor,
> with the effect that once one visitor returned an error, each later
> visitor would notice that it had been passed in an Error** representing
> an already set error, and do nothing.
> 
> For the case of visit_type_str() we also need to handle the case where
> an error means that the visitor doesn't set our char*. We initialize
> the pointer to NULL so we can safely g_free() it regardless of whether
> the visitor allocated a string for us or not.
> 
> 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 when
> visit_type_str() failed.].
> 
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> For 1.4 because it fixes a crash bug in the test.

Applied to the qmp branch, thanks.

> 
> v1->v2 changes: I took Luiz' suggestions for simplifying this code:
> just pass NULL in as an Error** since we don't care about errors, and
> NULL-init sres so g_free() works either way.
> 
> I agree with Luiz that the test leaks visitors, but since it won't leak
> enough to actually cause a problem, I leave that for a post-1.4 patch,
> since it's a separate bug to the one we're fixing here.
> 
>  tests/test-string-input-visitor.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/tests/test-string-input-visitor.c 
> b/tests/test-string-input-visitor.c
> index f6b0093..5989f81 100644
> --- a/tests/test-string-input-visitor.c
> +++ b/tests/test-string-input-visitor.c
> @@ -174,7 +174,6 @@ static void test_visitor_in_fuzz(TestInputVisitorData 
> *data,
>      double nres;
>      char *sres;
>      EnumOne eres;
> -    Error *errp = NULL;
>      Visitor *v;
>      unsigned int i;
>      char buf[10000];
> @@ -193,21 +192,22 @@ static void test_visitor_in_fuzz(TestInputVisitorData 
> *data,
>          }
>  
>          v = visitor_input_test_init(data, buf);
> -        visit_type_int(v, &ires, NULL, &errp);
> +        visit_type_int(v, &ires, NULL, NULL);
>  
>          v = visitor_input_test_init(data, buf);
> -        visit_type_bool(v, &bres, NULL, &errp);
> +        visit_type_bool(v, &bres, NULL, NULL);
>          visitor_input_teardown(data, NULL);
>  
>          v = visitor_input_test_init(data, buf);
> -        visit_type_number(v, &nres, NULL, &errp);
> +        visit_type_number(v, &nres, NULL, NULL);
>  
>          v = visitor_input_test_init(data, buf);
> -        visit_type_str(v, &sres, NULL, &errp);
> +        sres = NULL;
> +        visit_type_str(v, &sres, NULL, NULL);
>          g_free(sres);
>  
>          v = visitor_input_test_init(data, buf);
> -        visit_type_EnumOne(v, &eres, NULL, &errp);
> +        visit_type_EnumOne(v, &eres, NULL, NULL);
>          visitor_input_teardown(data, NULL);
>      }
>  }