Re: exim fixing %n (from deraadt@)

Stuart Henderson <stu@spacehopper.org> wrote:

> On 2021/09/20 13:09, Renaud Allard wrote:
> >
> >
> > On 9/20/21 11:32 AM, Stuart Henderson wrote:
> > > On 2021/09/20 10:29, Stuart Henderson wrote:
> > > > Some of these are pretty hairy and it's a moving codebase. Since they
> > > > are applying compiler "printf-like" attribute to functions which are
> > > > using their own functions rather than libc printf, and we are purely
> > > > making this change to disable the spurious warning because there is
> > > > no abort in their %n handling, can't we just disable the annotations
> > > > instead?
> > >
> > > actually my patch comment is too short, maybe this instead
> > >
> > > Don't do printf-like checks on Exim's internal printf-like functions on
> > > OpenBSD. libc printf functions abort() on %n use, and the compiler has
> > > been modified to warn about this; however this does not apply to Exim's
> > > functions which do still support %n.
> > >
> > >
> >
> > This is more a political decision on what we are trying to solve here,
> > compiler warnings or secure coding practices. In the end, I would like to
> > have Theo's point of view.
>
> The other patch doesn't solve anything other than false-positive warnings,
> because the implementation of their printf-like functions still supports %n.

We could include a patch which removes it.

We must eventually teach other systems that this is the way things are
going. It takes a decade.