On 2020/11/12 14:37, Markus Armbruster wrote:
> Alex Chen <alex.c...@huawei.com> writes:
>
>> In qobject_type(), NULL is returned when the 'QObject' returned from
>> parse_value() is not of QString type,
>> and this 'QObject' memory will leaked.
>> So we need to first check whether the 'QObject' returned from parse_value()
>> is of QString type,
>> and if not, we free 'QObject' memory and return an error.
>>
>> The memleak stack is as follows:
>> Direct leak of 32 byte(s) in 1 object(s) allocated from:
>> #0 0xfffe4b3c34fb in __interceptor_malloc (/lib64/libasan.so.4+0xd34fb)
>> #1 0xfffe4ae48aa3 in g_malloc (/lib64/libglib-2.0.so.0+0x58aa3)
>> #2 0xaaab3557d9f7 in qnum_from_int
>> /Images/source_org/qemu_master/qemu/qobject/qnum.c:25
>> #3 0xaaab35584d23 in parse_literal
>> /Images/source_org/qemu_master/qemu/qobject/json-parser.c:511
>> #4 0xaaab35584d23 in parse_value
>> /Images/source_org/qemu_master/qemu/qobject/json-parser.c:554
>> #5 0xaaab35583d77 in parse_pair
>> /Images/source_org/qemu_master/qemu/qobject/json-parser.c:270
>> #6 0xaaab355845db in parse_object
>> /Images/source_org/qemu_master/qemu/qobject/json-parser.c:327
>> #7 0xaaab355845db in parse_value
>> /Images/source_org/qemu_master/qemu/qobject/json-parser.c:546
>> #8 0xaaab35585b1b in json_parser_parse
>> /Images/source_org/qemu_master/qemu/qobject/json-parser.c:580
>> #9 0xaaab35583703 in json_message_process_token
>> /Images/source_org/qemu_master/qemu/qobject/json-streamer.c:92
>> #10 0xaaab355ddccf in json_lexer_feed_char
>> /Images/source_org/qemu_master/qemu/qobject/json-lexer.c:313
>> #11 0xaaab355de0eb in json_lexer_feed
>> /Images/source_org/qemu_master/qemu/qobject/json-lexer.c:350
>> #12 0xaaab354aff67 in tcp_chr_read
>> /Images/source_org/qemu_master/qemu/chardev/char-socket.c:525
>> #13 0xfffe4ae429db in g_main_context_dispatch
>> (/lib64/libglib-2.0.so.0+0x529db)
>> #14 0xfffe4ae42d8f (/lib64/libglib-2.0.so.0+0x52d8f)
>> #15 0xfffe4ae430df in g_main_loop_run (/lib64/libglib-2.0.so.0+0x530df)
>> #16 0xaaab34d70bff in iothread_run
>> /Images/source_org/qemu_master/qemu/iothread.c:82
>> #17 0xaaab3559d71b in qemu_thread_start
>> /Images/source_org/qemu_master/qemu/util/qemu-thread-posix.c:519
>
> Good catch, thanks!
>
>> Fixes: 532fb5328473 ("qapi: Make more of qobject_to()")
>> Reported-by: Euler Robot <euler.ro...@huawei.com>
>> Signed-off-by: Alex Chen <alex.c...@huawei.com>
>> Signed-off-by: Chen Qun <kuhn.chen...@huawei.com>
>> ---
>> qobject/json-parser.c | 9 ++++++---
>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/qobject/json-parser.c b/qobject/json-parser.c
>> index d083810d37..b37762a203 100644
>> --- a/qobject/json-parser.c
>> +++ b/qobject/json-parser.c
>> @@ -267,10 +267,13 @@ static int parse_pair(JSONParserContext *ctxt, QDict
>> *dict)
>> goto out;
>> }
>>
>> - key = qobject_to(QString, parse_value(ctxt));
>> - if (!key) {
>> - parse_error(ctxt, peek, "key is not a string in object");
>> + value = parse_value(ctxt);
>> + if (!value || qobject_type(value) != QTYPE_QSTRING) {
>
> The "is string" test becomes more cumbersome. Also, we reuse @value for
> another purpose.
>
>> + qobject_unref(value);
>> + parse_error(ctxt, peek, "value is not a string in object");
>
> Changing error messages in a memory leak fix is inappropriate.
> Accident?
>
>> goto out;
>> + } else {
>> + key = qobject_to(QString, value);
>> }
>>
>> token = parser_context_pop_token(ctxt);
>
> Here's a simpler, straightforward fix, with a test case thrown in:
>
> diff --git a/qobject/json-parser.c b/qobject/json-parser.c
> index d083810d37..c0f521b56b 100644
> --- a/qobject/json-parser.c
> +++ b/qobject/json-parser.c
> @@ -257,8 +257,9 @@ static JSONToken
> *parser_context_peek_token(JSONParserContext *ctxt)
> */
> static int parse_pair(JSONParserContext *ctxt, QDict *dict)
> {
> + QObject *key_obj = NULL;
> + QString *key;
> QObject *value;
> - QString *key = NULL;
> JSONToken *peek, *token;
>
> peek = parser_context_peek_token(ctxt);
> @@ -267,7 +268,8 @@ static int parse_pair(JSONParserContext *ctxt, QDict
> *dict)
> goto out;
> }
>
> - key = qobject_to(QString, parse_value(ctxt));
> + key_obj = parse_value(ctxt);
> + key = qobject_to(QString, key_obj);
> if (!key) {
> parse_error(ctxt, peek, "key is not a string in object");
> goto out;
> @@ -297,13 +299,11 @@ static int parse_pair(JSONParserContext *ctxt, QDict
> *dict)
>
> qdict_put_obj(dict, qstring_get_str(key), value);
>
> - qobject_unref(key);
> -
> + qobject_unref(key_obj);
> return 0;
>
> out:
> - qobject_unref(key);
> -
> + qobject_unref(key_obj);
> return -1;
> }
>
> diff --git a/tests/check-qjson.c b/tests/check-qjson.c
> index 07a773e653..9a02079099 100644
> --- a/tests/check-qjson.c
> +++ b/tests/check-qjson.c
> @@ -1415,6 +1415,14 @@ static void invalid_dict_comma(void)
> g_assert(obj == NULL);
> }
>
> +static void invalid_dict_key(void)
> +{
> + Error *err = NULL;
> + QObject *obj = qobject_from_json("{32:'abc'}", &err);
> + error_free_or_abort(&err);
> + g_assert(obj == NULL);
> +}
> +
> static void unterminated_literal(void)
> {
> Error *err = NULL;
> @@ -1500,6 +1508,7 @@ int main(int argc, char **argv)
> g_test_add_func("/errors/unterminated/dict_comma",
> unterminated_dict_comma);
> 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/invalid_dict_key", invalid_dict_key);
> g_test_add_func("/errors/unterminated/literal", unterminated_literal);
> g_test_add_func("/errors/limits/nesting", limits_nesting);
> g_test_add_func("/errors/multiple_values", multiple_values);
>
Thanks for your review，your patch is better than mine.
I will send the patch v2.
Thanks,
Alex
