RFR JDK-8008972

[Chris Hegarty]

This looks fine to me John. Thanks for persisting with me to get thus done.

-Chris

On 31 May 2013, at 18:06, John Zavgren <john.zavgren at oracle.com> wrote:

> All:
> I have a revised webrev image that's ready for review:
> http://cr.openjdk.java.net/~jzavgren/8008972/webrev.04/
> 
> Thanks
> John
> 
> On 05/13/2013 04:14 PM, John Zavgren wrote:
>> Greetings:
>> I posted a new webrev image:
>> http://cr.openjdk.java.net/~jzavgren/8008972/webrev.03/
>> that fixes a memory leak.
>> 
>> The leak in src/windows/native/java/net/DualStackPlainDatagramSocketImpl.c is caused  by an unfortunate interplay between two actions:
>> 1.) dynamically allocating a larger packet buffer when the length of an incoming packet exceeds MAX_BUFFER_LEN.
>> 2.) truncating a received packet so that it's length equals MAX_PACKET_LEN, when it exceeds this value.
>> 
>> Action number two was embedded inside the code that implemented action number one, and action number two can change the length of the packet. Unfortunately, the original packet length was used as an indication that the packet buffer needed to be freed, and because the length of the packet may have changed after the allocation, the free() statement wasn't being executed in some cases.
>> 
>> I fixed the problem by moving action number two so that it always precedes action number 1. This ensures that the packet length retains the same value across the malloc() and the free() operations, and therefore packet length can now be used as a reliable indication that dynamically allocated memory must be freed.
>> 
>> I also noticed that there is a procedure in src/windows/native/java/net/TwoStacksPlainDatagramSocketImpl.c that also dynamically allocates memory in a similar way, but it doesn't implement action number two. I added it.
>> 
>> I also took advantage of this opportunity to fix spelling errors in other files in the same directory as the two previously mentioned files.
>> 
>> 
>> On 03/04/2013 01:17 PM, Chris Hegarty wrote:
>>> On 03/04/2013 04:28 PM, John Zavgren wrote:
>>>> Greetings:
>>>> 
>>>> I've posted a webrev image of a memory leak fix:
>>>> http://cr.openjdk.java.net/~jzavgren/8008972/webrev.01/
>>> 
>>> Sorry John, I don't see what the problem is that you are trying to solve? Can you please explain why the original code has problems?
>>> 
>>> Also, note that there are other places in the same function that do the very same check.
>>> 
>>> -Chris.
>>> 
>>>> 
>>>> Thanks!
>>>> John
> 
> -- 
> John Zavgren
> john.zavgren at oracle.com
> 603-821-0904
> US-Burlington-MA
>