Re: [PATCH v1 2/2] perf record: Fix a asan runtime error in util/maps.c

[Ian Rogers]

On Wed, Feb 26, 2025 at 9:39 PM Chun-Tse Shao <ctshao@xxxxxxxxxx> wrote:
>
> If I build perf with asan and run Zstd test:
>
>   $ make -C tools/perf O=/tmp/perf DEBUG=1 EXTRA_CFLAGS="-O0 -g -fno-omit-frame-pointer -fsanitize=undefined"
>   $ /tmp/perf/perf test "Zstd perf.data compression/decompression" -vv
>    83: Zstd perf.data compression/decompression:
>   ...
>   util/maps.c:1046:5: runtime error: null pointer passed as argument 2, which is declared to never be null
>   ...
>
> The issue was caused by `bsearch`. The patch adds a check to ensure
> argument 2 and 3 are not NULL and 0.
>
> Testing with the commands above confirms that the runtime error is
> resolved.
>
> Signed-off-by: Chun-Tse Shao <ctshao@xxxxxxxxxx>

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

Thanks,
Ian

> ---
>  tools/perf/util/maps.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/maps.c b/tools/perf/util/maps.c
> index 09c9cc326c08..41a99e1f4b50 100644
> --- a/tools/perf/util/maps.c
> +++ b/tools/perf/util/maps.c
> @@ -1042,10 +1042,13 @@ struct map *maps__find(struct maps *maps, u64 ip)
>         while (!done) {
>                 down_read(maps__lock(maps));
>                 if (maps__maps_by_address_sorted(maps)) {
> -                       struct map **mapp =
> -                               bsearch(&ip, maps__maps_by_address(maps), maps__nr_maps(maps),
> -                                       sizeof(*mapp), map__addr_cmp);
> +                       struct map **mapp = NULL;
> +                       struct map **maps_by_address = maps__maps_by_address(maps);
> +                       unsigned int nr_maps = maps__nr_maps(maps);
>
> +                       if (maps_by_address && nr_maps)
> +                               mapp = bsearch(&ip, maps_by_address, nr_maps, sizeof(*mapp),
> +                                              map__addr_cmp);
>                         if (mapp)
>                                 result = map__get(*mapp);
>                         done = true;
> --
> 2.48.1.658.g4767266eb4-goog
>