Re: [PATCH 3/3] module: Add compile-time check for embedded NUL characters

Sami Tolvanen
2025-12-11T17:03:40Z

On Thu, Dec 11, 2025 at 12:28 AM Dan Carpenter <dan.carpenter@linaro.org> wrote:
>
> On Wed, Dec 10, 2025 at 02:29:45PM -0800, Luck, Tony wrote:
> > > diff --git a/expand.c b/expand.c
> > > index f14e7181..71221d35 100644
> > > --- a/expand.c
> > > +++ b/expand.c
> > > @@ -535,6 +535,8 @@ static int expand_compare(struct expression *expr)
> > > expr->taint = 0;
> > > return 0;
> > > }
> > > + if (left->flags & CEF_ICE && right->flags & CEF_ICE)
> > > + expr->flags |= CEF_SET_ICE;
> > > if (simplify_cmp_binop(expr, left->ctype))
> > > return 0;
> > > if (simplify_float_cmp(expr, left->ctype))
>
> I'm not an expert in the C standard, but this feels correct to me.

It only fixes comparisons though, the problem still exists for other
expressions. For example, while `_Static_assert(__builtin_strlen("")
== 0);` works with this change,
`_Static_assert(!__builtin_strlen(""));` still fails. Perhaps there's
a better way to fix this than changing each expression expansion
function to handle this flag?

Sami