Re: [PATCH v1] perf string: Avoid undefined NULL+1

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Mon, Dec 09, 2024 at 11:49:15AM +0000, James Clark wrote:
> On 20/11/2024 6:52 am, Ian Rogers wrote:
> > While the value NULL+1 is never used it triggers a ubsan
> > warning. Restructure and comment the loop to avoid this.

> > Signed-off-by: Ian Rogers <irogers@google.com>
> > +++ b/tools/perf/util/string.c
> > @@ -254,11 +254,20 @@ char *strpbrk_esc(char *str, const char *stopset)
> >   	do {
> >   		ptr = strpbrk(str, stopset);
> > -		if (ptr == str ||
> > -		    (ptr == str + 1 && *(ptr - 1) != '\\'))
> > +		if (!ptr) {
> > +			/* stopset not in str. */
> >   			break;
> > +		}
> > +		if (ptr == str) {
> > +			/* stopset character is first in str. */
> > +			break;
> > +		}
> > +		if (ptr == str + 1 && str[0] != '\\') {
> > +			/* stopset chacter is second and wasn't preceded by a '\'. */
> > +			break;
> > +		}
> >   		str = ptr + 1;
> > -	} while (ptr && *(ptr - 1) == '\\' && *(ptr - 2) != '\\');
> > +	} while (ptr[-1] == '\\' && ptr[-2] != '\\');
> >   	return ptr;
> >   }
 
> Reviewed-by: James Clark <james.clark@linaro.org>

Thanks, applied to perf-tools-next,

- Arnaldo