GNU_STACK ELF header

[Douglas Simon]

On Aug 27, 2010, at 7:49 PM, Dr Andrew John Hughes wrote:

> On 27 August 2010 16:31, Kelly O'Hair <kelly.ohair at oracle.com> wrote:
>> Interesting. Had not heard about this new Elf header.
>> 
>> The Linux systems and gcc compilers used for jdk5 and jdk6 builds is pretty
>> old.
>> 
>> 32bit:
>> gcc (GCC) 3.2.1-7a (J2SE release)
>> 
>> 64bit:
>> gcc (GCC) 3.2.2 (SuSE Linux)
>> 
>> For jdk7, we are using the gcc compiler provided with Fedora 9,  gcc 4.3.0
>> 
>> -kto
>> 
>> 
>> On Aug 26, 2010, at 11:25 PM, Douglas Simon wrote:
>> 
>>> As a result of stack overflow detection breaking in Maxine on Linux, I
>>> learnt about this ELF header. My experience is described here:
>>> http://blogs.sun.com/dns/entry/stacks_with_split_personalities
>>> 
>>> Is this issue known in HotSpot/JDK? If so, how exactly is the header being
>>> omitted from the HotSpot and JDK libraries and executables?
>>> 
>>> -Doug
>> 
>> 
> 
> This was discussed last year:
> http://mail.openjdk.java.net/pipermail/distro-pkg-dev/2009-August/006995.html
> and is patched in IcedTea6 by icedtea-gcc-stack-markings.patch.
> 
> GCC 4.3 is the earliest version of GCC IcedTea has been built with, to
> my knowledge, rather than the latest.  I'm currently building with GCC
> 4.5.1.


If I understand the patch correctly, it still leaves an IcedTea process in the position where all stacks are made executable if an 'executable-stack' native library is loaded. As far as I can tell, there's no way to really avoid this given the behaviour of the dynamic linker on Linux. Or am I missing something?

-Doug