Re: [PATCH v2 5/9] seq_buf: Add seq_buf_strlen()

[Kees Cook <kees@kernel.org>]

On Sat, Sep 19, 2026 at 08:38:37AM +0100, Greg KH wrote:
> On Fri, Sep 18, 2026 at 05:27:03PM -0700, Kees Cook wrote:
> > +static inline size_t seq_buf_strlen(struct seq_buf *s)
> > +{
> > +	if (WARN_ON(s->size == 0))
> > +		return 0;
> 
> Why WARN_ON()?  Are you wanting to just mint new CVEs with this code
> path, do we not give out enough already?  :)
> 
> I can see returning 0, if it's empty, but isn't that a valid check for
> people to wish to know at times?  Why crash the box?  (remember about
> panic-on-warn being enabled in a few billion Linux instances...)

We have to figure out a line somewhere. :P Making a seq_buf with size 0
is a nonsense construction, but seq_buf_init is non-allocating, so
there's no feedback about setting it to size 0. We could move the WARN
to the init? I was just following the existing style here.

I'm happy to remove it.

-- 
Kees Cook