RELEASE BLOCKER: Linux doesn't follow x86/x86-64 ABI wrt direction flag

[Paolo Bonzini]

>>  If the malicious process can send a signal to another process, it
>>  could also ptrace() it. Which is more useful, if you wanted to be
>>  malicious?
> 
> And more to the point, it can happen before GCC 4.3.0.

Yes, and that's why the kernel should just fix it, and the fix should be 
backported and treated like any other security fix.

Paolo