FW: Sporadic permission denied error in Samba 4.3 and 4.4, 4.2 OK

[Jeremy Allison]

On Mon, Nov 14, 2016 at 09:42:53PM +0000, Youzhong Yang wrote:
> Yes, it's illumos/SmartOS system running Samba. It's possible there's some kind of bug either in kernel or in user-land programming. If you guys can point out a few critical points to put debug statements, I would be more than happy to debug the issue here.

There's no magic debug that will show a kernel
bug. If you're reporting it right, the issue is
on 4.5.x on your kernel a sendmsg() call on a
connected UNIX domain socket is dropping the
message.

That simply should not happen. For a lease break
message this isn't anything fancy such as fd-passing,
this should be a simple datagram message.

Look at the test program in:

source3/lib/unix_msg/test_source.c

Ensure this works correctly on your kernel.

Can you run directly out of master on a test
system, so we know we're looking at identical
code ?

Jeremy.