Re: [PATCH] lib/vsprintf: Fix to check field_width and precision

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Thu, 19 Mar 2026 09:11:21 +0200
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:

> On Thu, Mar 19, 2026 at 09:26:59AM +0900, Masami Hiramatsu (Google) wrote:
> 
> > Check the field_width and presition correctly. Previously it depends
> > on the bitfield conversion from int to check out-of-range error.
> > However, commit 938df695e98d ("vsprintf: associate the format state
> > with the format pointer") changed those fields to int.
> > We need to check the out-of-range correctly without bitfield
> > conversion.
> 
> ...
> 
> >  	spec->field_width = width;
> > -	if (WARN_ONCE(spec->field_width != width, "field width %d too large", width)) {
> > +	if (WARN_ONCE(spec->field_width > FIELD_WIDTH_MAX ||
> > +		      spec->field_width < -FIELD_WIDTH_MAX, "field width %d too large", width)) {
> 
> Also use logical split as below:
> 
> 	if (WARN_ONCE(spec->field_width > FIELD_WIDTH_MAX || spec->field_width < -FIELD_WIDTH_MAX,
> 		      "field width %d too large", width)) {

OK, let me update it.

Thanks,

> 
> >  		spec->field_width = clamp(width, -FIELD_WIDTH_MAX, FIELD_WIDTH_MAX);
> >  	}
> >  }
> 
> ...
> 
> >  	spec->precision = prec;
> > -	if (WARN_ONCE(spec->precision != prec, "precision %d too large", prec)) {
> > +	if (WARN_ONCE(spec->precision > PRECISION_MAX || spec->precision < 0,
> > +		      "precision %d too large", prec)) {
> >  		spec->precision = clamp(prec, 0, PRECISION_MAX);
> >  	}
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>