RFR: 8049695: nsk/jdb/options/connect/connect003 fails with "Launched jdb could not attach to debuggee during 300000 milliseconds"

[Alex Menkov]

Hi Serguei,

On 03/14/2018 17:33, serguei.spitsyn at oracle.com wrote:
> Hi Alex,
> 
> Sorry to being late to this party.
> Thank you for getting to the root cause of this issue and for extra 
> updates.
> All such issues are important for test stabilization, so now there will 
> be one problem less!
> 
> This looks pretty good to me.
> I'd replace "objectName" with "streamName" to keep it unified.

In createStream() and createTransport() the buffer is used to generate 
names for mutex and events (kind of "Windows objects").
In createConnection() the buffer is used to generate stream names 
(client->server & server->client streams).

--alex

> But I understand why you are trying to avoid using "streamName" in this 
> particular case.
> It is because we already have the argument "name" for the stream, so 
> there can be
> a confusion why do we have also "streamName" as the argument already 
> took this role.
> A better name for argument would be "baseName" (or "prefix") to avoid 
> this confusion.
> But I think, this confusion is not that big, so the "streamName" should 
> be fine.
> 
> I leave it up to you and other reviewers.
> 
> Thanks,
> Serguei
> 
> 
> On 3/14/18 16:28, Alex Menkov wrote:
>> Hi Chris,
>>
>> On 03/14/2018 13:42, Chris Plummer wrote:
>>> Hi Alex,
>>>
>>> I don't think prefix -> basename is what David had in mind. Those 
>>> basically mean the same thing. The buffer is being used for the full 
>>> name, which is why neither is really appropriate. So maybe just call 
>>> it fullname, or even just name. createConnection() has a similar 
>>> prefix reference that should be fixed.
>>
>> Ok, I don't like "fullname", "name" is already used there, so I made 
>> them "objectName" (for mutex/event names) and streamName (for stream 
>> name in createConnection()).
>>
>> updated webrev:
>> http://cr.openjdk.java.net/~amenkov/shmem_long_name/webrev_open.03/
>>
>> --alex
>>
>>>
>>> thanks,
>>>
>>> Chris
>>>
>>> On 3/14/18 12:43 PM, Alex Menkov wrote:
>>>>
>>>> Updated fix:
>>>> http://cr.openjdk.java.net/~amenkov/shmem_long_name/webrev_open.02/
>>>>
>>>> The changes:
>>>> - createTransport function is fixed;
>>>> - "prefix" variable is renamed to "baseName".
>>>>
>>>> --alex
>>>>
>>>> On 03/14/2018 09:45, Alex Menkov wrote:
>>>>> Hi David,
>>>>>
>>>>>
>>>>> On 03/13/2018 17:46, David Holmes wrote:
>>>>>> Hi Alex,
>>>>>>
>>>>>> On 14/03/2018 9:14 AM, Alex Menkov wrote:
>>>>>>> Hi all,
>>>>>>>
>>>>>>> Please review a small fix for
>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8049695
>>>>>>> webrev: 
>>>>>>> http://cr.openjdk.java.net/~amenkov/shmem_long_name/webrev_open/
>>>>>>>
>>>>>>> Root cause of the issue is jbd hungs as a result of the buffer 
>>>>>>> overflow.
>>>>>>>
>>>>>>> In the beginning of the shmemBase.c:
>>>>>>>
>>>>>>> #define MAX_IPC_PREFIX 50   /* user-specified or generated name 
>>>>>>> for */
>>>>>>>                              /* shared memory seg and prefix for 
>>>>>>> other IPC */
>>>>>>> #define MAX_IPC_SUFFIX 25   /* suffix to shmem name for other IPC 
>>>>>>> names */
>>>>>>> #define MAX_IPC_NAME   (MAX_IPC_PREFIX + MAX_IPC_SUFFIX)
>>>>>>>
>>>>>>> buffer (char prefix[]) in function createStream is used to 
>>>>>>> generate base name for mutex/events, so MAX_IPC_PREFIX is not big 
>>>>>>> enough.
>>>>>>
>>>>>> Good catch! But overall this code seems to be missing bounds 
>>>>>> checks everywhere. You made the "prefix" (poor name?) buffer 
>>>>>> bigger (MAX_IPC_NAME) but do we know the incoming name plus the 
>>>>>> appended descriptive string will fit in it?
>>>>>
>>>>> Yes, the possible values can be added to the shmem name (which is 
>>>>> restricted by 49 chars):
>>>>> ".mutex"
>>>>> ".hasData"
>>>>> ".hasSpace"
>>>>> ".accept"
>>>>> ".attach"
>>>>> ".<pid>" (pid is 64bit value, max len IIRC is 19 symbols)
>>>>> So extra MAX_IPC_SUFFIX (25 symbols) is enough
>>>>>
>>>>>> Looking at createTransport for example, it also has:
>>>>>>
>>>>>> char prefix[MAX_IPC_PREFIX];
>>>>>>
>>>>>> and it produces an error if
>>>>>>
>>>>>> strlen(address) >= MAX_IPC_PREFIX
>>>>>>
>>>>>> but otherwise copies it across:
>>>>>>
>>>>>> strcpy(transport->name, address);
>>>>>>
>>>>>> and then later does:
>>>>>>
>>>>>>   sprintf(prefix, "%s.mutex", transport->name);
>>>>>>
>>>>>> so we may have overflowed again by adding ".mutex"! The same goes 
>>>>>> for the subsequent sprintf's.
>>>>>
>>>>> Thank you for the catch!
>>>>> I looked the file for other similar issues, but somehow overlokked 
>>>>> this case.
>>>>> Will fix it.
>>>>> Also will change confusing "prefix" name to "base_name".
>>>>>
>>>>> --alex
>>>>>
>>>>>>
>>>>>> So I think there is more work to do to ensure this code is immune 
>>>>>> from buffer overflows.
>>>>>>
>>>>>> Thanks,
>>>>>> David
>>>>>> -----
>>>>>>
>>>>>>> --alex
>>>
>>>
>>>
>