RFR: 8205342: windows : potential memleaks in getAdapter(s) in NetworkInterface_winXP.c

[Thomas Stüfe]

Hi Matthias,

okay, if it is simplicity you are after, you could completely remove
the truncation handling too, since a buffer with 100 bytes leaves you
29 bytes for 29 digits; that is more than enough to display an int
even if it were 64bit (uint64 max = 18,446,744,073,709,551,615, 20
digits).

But I leave it up to you. The important thing is that the memory leak
gets fixed.

Reviewed from my end. Thanks, Thomas


On Wed, Jun 20, 2018 at 11:05 AM, Baesken, Matthias
<matthias.baesken at sap.com> wrote:
> Hi Thomas, I considered it but then I thought that the coding gets a bit simpler with a fix buffer .
>
> Best regards, Matthias
>
>> -----Original Message-----
>> From: Thomas Stüfe [mailto:thomas.stuefe at gmail.com]
>> Sent: Mittwoch, 20. Juni 2018 10:26
>> To: Baesken, Matthias <matthias.baesken at sap.com>
>> Cc: net-dev at openjdk.java.net
>> Subject: Re: RFR: 8205342: windows : potential memleaks in getAdapter(s) in
>> NetworkInterface_winXP.c
>>
>> Hi Matthias,
>>
>> thanks, good catch about the leak.
>>
>> But could you not just simply free the error_msg_buf after the call to
>> JNU_ThrowByName?
>>
>> JNU_ThrowByName copies the message string, so no need to keep it alive
>> afterwards:
>>
>> diff -r e810abb27deb
>> src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>> --- a/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>>  Wed Jun 20 06:51:39 2018 +0200
>> +++ b/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>>  Wed Jun 20 10:21:57 2018 +0200
>> @@ -138,6 +138,7 @@
>>                      JNU_ThrowByName(env, "java/lang/Error",
>>                          "IP Helper Library GetAdaptersAddresses
>> function failure");
>>                  }
>> +                free(error_msg_buf);
>>              } else {
>>                  JNU_ThrowByName(env, "java/lang/Error",
>>                      "IP Helper Library GetAdaptersAddresses function failed");
>>
>> Thanks, Thomas
>>
>>
>>
>> On Wed, Jun 20, 2018 at 10:07 AM, Baesken, Matthias
>> <matthias.baesken at sap.com> wrote:
>> > Hello . Please review this small  fix that  fixes  potential  memory leaks
>> > in   getAdapter(s) in NetworkInterface_winXP.c  and simplifies the coding a
>> > bit too .
>> >
>> > Currently   when generating error messages ,   some memory  is malloc-ed
>> > for the error messages , but not always freed .
>> >
>> >
>> >
>> >
>> >
>> > Bug:
>> >
>> >
>> >
>> > https://bugs.openjdk.java.net/browse/JDK-8205342
>> >
>> >
>> >
>> > webrev :
>> >
>> >
>> >
>> > http://cr.openjdk.java.net/~mbaesken/webrevs/8205342/
>> >
>> >
>> >
>> >
>> >
>> > Thanks, Matthias
>> >
>> >
>> >
>> >