Re: [Qemu-devel] [RFC] Continuous work on sandboxing

[Paolo Bonzini]

Il 26/04/2013 23:07, Paul Moore ha scritto:
>> > 3. Debugging and/or learning mode - third party libraries still have the
>> > problem of interfering in the Qemu's signal mask. According to some
>> > previous discussions, perhaps patch all external libraries that mass up
>> > with this mask (spice, for example) is a way to solve it. But not sure
>> > if it worth the time spent. Would like to hear you guys.
> I think patching all the libraries is a losing battle, I think we need to 
> pursue alternate debugging techniques.

It is really only about patching libraries that create threads _and_
block all signals in the newly-created thread (to not interfere with the
program's own handling of the signals).  In this case, the per-thread
signals (SIGFPE/SIGSEGV/SIGBUS/SIGSYS/SIGILL) should be left unblocked,
but SIGSYS is often forgotten.

I don't think there are many libraries like this, but fixing SPICE at
least should definitely be welcome.

In fact QEMU's own util/qemu-thread-posix.c does not unblock those
signals.  Eduardo, can you submit a patch for that?

Paolo