Re: [Qemu-devel] [PATCH 1/2] hmp: expr_unary(): check for overflow in strtoul()/strtoull()

[Luiz Capitulino]

On Fri, 27 Apr 2012 15:28:56 +0200
Markus Armbruster <address@hidden> wrote:

> Luiz Capitulino <address@hidden> writes:
> 
> > It's not checked currently, so something like:
> >
> >   (qemu) balloon -100000000000001111114334234
> >   (qemu)
> >
> > Will just "work" (in this case the balloon command will get a random
> > value).
> >
> > Fix it by checking if strtoul()/strtoull() overflowed.
> >
> > Signed-off-by: Luiz Capitulino <address@hidden>
> > ---
> >  monitor.c |    7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/monitor.c b/monitor.c
> > index 8946a10..56ee971 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -3120,10 +3120,17 @@ static int64_t expr_unary(Monitor *mon)
> >          n = 0;
> >          break;
> >      default:
> > +        errno = 0;
> >  #if TARGET_PHYS_ADDR_BITS > 32
> >          n = strtoull(pch, &p, 0);
> > +        if (n == ULLONG_MAX && errno == ERANGE) {
> > +            expr_error(mon, "number too large");
> > +        }
> >  #else
> >          n = strtoul(pch, &p, 0);
> > +        if (n == ULONG_MAX && errno == ERANGE) {
> > +            expr_error(mon, "number too large");
> > +        }
> >  #endif
> >          if (pch == p) {
> >              expr_error(mon, "invalid char in expression");
> 
> Roundabout way to do
> 
> +        errno = 0;
>  #if TARGET_PHYS_ADDR_BITS > 32
>          n = strtoull(pch, &p, 0);
>  #else
>          n = strtoul(pch, &p, 0);
>  #endif
> +        if (errno == ERANGE) {
> +            expr_error(mon, "number too large");
> +        }
>          if (pch == p) {
>              expr_error(mon, "invalid char in expression");

I really have a preference for doing what's described by the standard. At
the same time I think this is really minor.

The duplication you're fixing is going to be fixed once we introduce
a wrapper for strtoul()/stroull().