linux-kernel - [PATCH v1 6/8] perf maps: Avoid UB passing NULL to bsearch

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Message-Id: <20241213210425.526512-7-irogers@google.com>
Date: Fri, 13 Dec 2024 13:04:23 -0800
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, "Mike Rapoport (IBM)" <rppt@...nel.org>, 
	Wei Yang <richard.weiyang@...il.com>, James Clark <james.clark@...aro.org>, 
	Howard Chu <howardchu95@...il.com>, Kajol Jain <kjain@...ux.ibm.com>, 
	Athira Rajeev <atrajeev@...ux.vnet.ibm.com>, Ze Gao <zegao2021@...il.com>, 
	Weilin Wang <weilin.wang@...el.com>, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org
Subject: [PATCH v1 6/8] perf maps: Avoid UB passing NULL to bsearch

If maps_by_address is NULL it is UB to pass it to bsearch, and will
trigger ubsan, even if the nr_maps is 0.

Fixes: 659ad3492b91 ("perf maps: Switch from rbtree to lazily sorted array for addresses")
Signed-off-by: Ian Rogers <irogers@...gle.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 432399cbe5dd..1830ae776052 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;
 
+			if (maps__maps_by_address(maps)) {
+				mapp = bsearch(&ip, maps__maps_by_address(maps),
+					       maps__nr_maps(maps), sizeof(*mapp),
+					       map__addr_cmp);
+			}
 			if (mapp)
 				result = map__get(*mapp);
 			done = true;
-- 
2.47.1.613.gc27f4b7a9f-goog