Eric Blake <[email protected]> writes:
> On 10/29/2015 06:44 AM, Markus Armbruster wrote:
>> This would have prevented the regression mentioned in the previous
>> commit.
>>
>> Signed-off-by: Markus Armbruster <[email protected]>
>> ---
>> tests/check-qjson.c | 29 +++++++++++++++++++++++++++++
>> 1 file changed, 29 insertions(+)
>
> Better late than never.
>
>> +++ b/tests/check-qjson.c
>> @@ -1484,6 +1484,34 @@ static void unterminated_literal(void)
>> g_assert(obj == NULL);
>> }
>>
>> +static char *make_nest(char *buf, size_t cnt)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < cnt - 1; i++) {
>> + buf[i] = '[';
>> + buf[2 * cnt - i - 1] = ']';
>> + }
>> + buf[cnt - 1] = '{';
>> + buf[cnt] = '}';
>> + buf[2 * cnt] = 0;
>> + return buf;
>> +}
>
> So buf must be at least 2*cnt+1 bytes long. (Function is static, so
> lack of comments don't hurt too badly). For a cnt of 3 (buffer size at
> least 7), this creates "[[{}]]". Larger cnt adds more outer [] pairs.
> The mixed content proves that patch 1/4 covers the combined limit of []
> and {} when counting nesting.
>
> Minor optimization - make the for loop bound be 'i < cnt - 2', so you
> aren't writing [] in the middle just to rewrite it to {} after the loop
> (works as long as caller never passes cnt == 1, which happens to be the
> case).
The loop's first assignment fills 0..cnt-2 inclusive, the second one
fills 2*cnt-1..(2*cnt-1)-(cnt-2) = 2*cnt-1..cnt+1 inclusive.
If I need to respin, I'll change to a pair of memset().
>> +static void limits_nesting(void)
>> +{
>> + enum { max_nesting = 1024 }; /* see qobject/json-streamer.c */
>> + char buf[2 * (max_nesting + 1) + 1];
>> + QObject *obj;
>> +
>> + obj = qobject_from_json(make_nest(buf, max_nesting));
>> + g_assert(obj != NULL);
>> + qobject_decref(obj);
>
> Proves that we can hit our max,
>
>> +
>> + obj = qobject_from_json(make_nest(buf, max_nesting + 1));
>> + g_assert(obj == NULL);
>
> and that we gracefully diagnose one beyond max.
>
>> +}
>> +
>> int main(int argc, char **argv)
>> {
>> g_test_init(&argc, &argv, NULL);
>> @@ -1519,6 +1547,7 @@ int main(int argc, char **argv)
>> g_test_add_func("/errors/invalid_array_comma", invalid_array_comma);
>> g_test_add_func("/errors/invalid_dict_comma", invalid_dict_comma);
>> g_test_add_func("/errors/unterminated/literal", unterminated_literal);
>> + g_test_add_func("/errors/limits/nesting", limits_nesting);
>>
>> return g_test_run();
>> }
>>
>
> Reviewed-by: Eric Blake <[email protected]>
