Re: [PATCH nf] netfilter: nf_nat: do not reuse an unexpected expectation on RTCP clash

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Jul 12, 2026 at 09:40:16AM +0200, Florian Westphal wrote:
> Greg KH <gregkh@linuxfoundation.org> wrote:
> > > I think this function should WARN_ON_ONCE when one tries to reinsert a
> > > dead expectation (and return -EINVAL or another appropriate error).
> > > 
> > > (This is indenpendent of the real fix).
> > 
> > If you do that, then the machine will reboot, loosing everything.
> > Are you sure you want that to happen?
> 
> Of course not, i never set panic_on_warn.

You don't, but a few billion Linux installs do :)

> > Why not just properly handle the
> > issue if it possibly could happen?
> 
> This is no different than the WARNs on list corruption or refcount
> under/overflows.

True, but adding new ones is not a good idea, and removing the existing
ones is a good idea.

> Would you propose to remove those?  I hope not, they help catch bugs.

Bugs that userspace can trigger?  If so, then properly catch them by
testing and handling the issue.  If userspace can never trigger it, then
it's not really needed as the code is never going to trigger.

thanks,

greg k-h