[PATCH v2 2/2] perf record: Fix a asan runtime error in util/maps.c

Chun-Tse Shao
2025-03-03T18:38:09Z

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@google.com>
---
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;
--
2.48.1.711.g2feabab25a-goog