Re: [PATCH v2] json: Fix a memleak in parse_pair()

[Philippe Mathieu-Daudé]

On 11/16/20 3:03 PM, Markus Armbruster wrote:
> Alex Chen <alex.chen@huawei.com> writes:
> 
>> On 2020/11/16 19:43, Philippe Mathieu-Daudé wrote:
>>> On 11/16/20 7:42 AM, Markus Armbruster wrote:
>>>> "Chenqun (kuhn)" <kuhn.chenqun@huawei.com> writes:
>>>>
>>>>>> -----Original Message-----
>>>>>> From: Chenzhendong (alex)
>>>>>> Sent: Friday, November 13, 2020 10:55 PM
>>>>>> To: armbru@redhat.com
>>>>>> Cc: Chenzhendong (alex) <alex.chen@huawei.com>; qemu-devel@nongnu.org;
>>>>>> qemu-trivial@nongnu.org; Zhanghailiang <zhang.zhanghailiang@huawei.com>;
>>>>>> Chenqun (kuhn) <kuhn.chenqun@huawei.com>
>>>>>> Subject: [PATCH v2] json: Fix a memleak in parse_pair()
>>>>>>
>>>>>> 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 cache the 'QObject' returned from parse_value(), and 
>>>>>> finally
>>>>>> free 'QObject' memory at the end of the function.
>>>>>> Also, we add a testcast about invalid dict key.
>>>>>>
>>>>>> 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
>>>>>>
>>> ...
>>>>
>>>> Queued, thanks!
>>>
>>> If possible can you s%/Images/source_org/qemu_master/qemu/%% to make
>>> description more readable...?
>>>
>>
>> Hi Philippe,
>> I am sorry for that, considering that the patch has been queued,
>> do I need to modify the commit message and send patch v3?

As the patch was already queued, this was a comment for the maintainer,
sorry for not being clear enough.

> 
> I'll take care of it, no need to respin.  Thanks!

Thanks!