perf record: Fix a asan runtime error in util/maps.c

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.

Reviewed-by: Ian Rogers <[email protected]>
Signed-off-by: Chun-Tse Shao <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Ben Gainey <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Leo Yan <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Nick Terrell <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: Chun-Tse Shao

tools/perf/util/maps.c

@@ -1082,10 +1082,13 @@ 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;