Re: [PATCH ethtool] netlink: fix print_string when the value is NULL

[Salvatore Bonaccorso <carnil@debian.org>]

Hi Michal,

On Fri, Aug 08, 2025 at 01:05:52AM +0200, Michal Kubecek wrote:
> On Thu, Jul 24, 2025 at 07:48:11PM GMT, Michel Lind wrote:
> > The previous fix in commit b70c92866102 ("netlink: fix missing headers
> > in text output") handles the case when value is NULL by still using
> > `fprintf` but passing no value.
> > 
> > This fails if `-Werror=format-security` is passed to gcc, as is the
> > default in distros like Fedora.
> > 
> > ```
> > json_print.c: In function 'print_string':
> > json_print.c:147:25: error: format not a string literal and no format arguments [-Werror=format-security]
> >   147 |                         fprintf(stdout, fmt);
> >       |
> > ```
> > 
> > Use `fprintf(stdout, "%s", fmt)` instead, using the format string as the
> > value, since in this case we know it is just a string without format
> > chracters.
> > 
> > Reviewed-by: Jakub Kicinski <kuba@kernel.org>
> > Signed-off-by: Michel Lind <michel@michel-slm.name>
> 
> Applied, thank you.
> 
> It's a bit surprising that I didn't hit this problem as I always test
> building with "-Wall -Wextra -Werror". I suppose this option is not
> contained in -Wall or -Wextra.
> 
> Michal
> 
> > ---
> >  json_print.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/json_print.c b/json_print.c
> > index e07c651..75e6cd9 100644
> > --- a/json_print.c
> > +++ b/json_print.c
> > @@ -144,7 +144,7 @@ void print_string(enum output_type type,
> >  		if (value)
> >  			fprintf(stdout, fmt, value);
> >  		else
> > -			fprintf(stdout, fmt);
> > +			fprintf(stdout, "%s", fmt);
> >  	}
> >  }
> >  
> > -- 
> > 2.50.1

As b70c92866102 ("netlink: fix missing headers in text output") was
backported as well for the 6.14.2 version, should that get as well a
new release 6.14.3 with the fix?

Regards,
Salvatore