Re: [PATCH net-next v2 1/2] keys, dns: drop unused upayload->data NUL terminator

Jakub Kicinski
2026-04-13T00:05:09Z

On Mon, 13 Apr 2026 01:04:54 +0200 Thorsten Blum wrote:
> On Sun, Apr 12, 2026 at 02:10:04PM -0700, Jakub Kicinski wrote:
> > On Fri, 10 Apr 2026 00:57:02 +0200 Thorsten Blum wrote:
> > > In dns_resolver_preparse(), do not NUL-terminate ->data and allocate one
> > > byte less. The NUL terminator is never used and only ->datalen bytes are
> > > accessed.
> >
> > I can't see where this is used at all.
> > Please write better commit messages, there's no way this 1 byte
> > is worth the amount of time I wasted trying to review this :/
>
> The point of patch 1/2 is not the removed NUL terminator itself, but to
> prepare for patch 2/2, which adds __counted_by() and requires ->datalen
> to match the number of elements in ->data.
>
> Currently, that is not the case because ->data includes an extra NUL
> despite never being used as a C string. Removing the unused terminator
> makes the length match the allocation size and allows adding the
> __counted_by() annotation.
>
> I can fold this into the __counted_by() patch if you prefer.

I understand that part, but I don't get where the data from which
the terminating character is removed, is used. Only other access
I saw was freeing it, the rest of the callback seem to looking
at the error, not the data..