commit 6ee3471968fe4c5ae449ded5795c38515cb54704
author Trinity Lundgren <trinit@google.com> Fri Jun 10 23:02:05 2022 +0000
committer CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com> Mon Jun 13 16:35:41 2022 +0000
tree 26698df4ceb48ee211cf8e82e3620b7f62ca4643
parent 7d7e7ad6223433f45af680f43ab4d75e23ad3257

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 <trinit@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>

pw_containers/flat_map_test.cc

diff --git a/pw_containers/flat_map_test.cc b/pw_containers/flat_map_test.cc
index 51cf005..bd236bd 100644
--- a/pw_containers/flat_map_test.cc
+++ b/pw_containers/flat_map_test.cc
@@ -178,4 +178,13 @@
   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

pw_containers/public/pw_containers/flat_map.h

diff --git a/pw_containers/public/pw_containers/flat_map.h b/pw_containers/public/pw_containers/flat_map.h
index b4c2ab5..9df709f 100644
--- a/pw_containers/public/pw_containers/flat_map.h
+++ b/pw_containers/public/pw_containers/flat_map.h
@@ -73,7 +73,10 @@
     }
 
     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 {