pw_containers: Check that FlatMap it is not end() before dereferencing

This bug results in asan errors when looking up keys that are larger than the max key in the flat map. Change-Id: Iad88f0138ff33b8b6f2ab6b10692ed7170d4fdfa Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/97801 Commit-Queue: Trinity Lundgren <[email protected]> Reviewed-by: Wyatt Hepler <[email protected]>
google · Jun 13, 2022 · 6ee3471 · 6ee3471
1 parent 7d7e7ad
commit 6ee3471
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diff --git a/pw_containers/flat_map_test.cc b/pw_containers/flat_map_test.cc
@@ -178,4 +178,13 @@ TEST(FlatMap, MapsWithUnsortedKeys) {
   EXPECT_EQ(too_short.begin()->first, 0);
 }
 
+TEST(FlatMap, DontDereferenceEnd) {
+  constexpr FlatMap<int, const char*, 2> unsorted_array({{
+      {2, "hello"},
+      {1, "goodbye"},
+  }});
+
+  EXPECT_EQ(unsorted_array.contains(3), false);
+}
+
 }  // namespace pw::containers
diff --git a/pw_containers/public/pw_containers/flat_map.h b/pw_containers/public/pw_containers/flat_map.h
@@ -73,7 +73,10 @@ class FlatMap {
     }
 
     const_iterator it = lower_bound(key);
-    return key == it->first ? it : end();
+    if (it == end() || it->first != key) {
+      return end();
+    }
+    return it;
   }
 
   constexpr const_iterator lower_bound(const key_type& key) const {