Merge pull request #1113 from igchor/ubsan_1.6

[stable-1.6] Ubsan fixes

Author: lukaszstolarczuk

include/libpmemobj++/detail/persistent_ptr_base.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2018, Intel Corporation
+ * Copyright 2016-2021, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -372,7 +372,10 @@ class persistent_ptr_base {
 	inline ptrdiff_t
 	calculate_offset() const
 	{
-		static const ptrdiff_t ptr_offset_magic = 0xDEADBEEF;
+		static const ptrdiff_t ptr_offset_magic = 0xF00000000000000;
+
+		static_assert(ptr_offset_magic % alignof(U) == 0, "");
+		static_assert(ptr_offset_magic % alignof(T) == 0, "");
 
 		U *tmp{reinterpret_cast<U *>(ptr_offset_magic)};
 		T *diff = static_cast<T *>(tmp);

include/libpmemobj++/experimental/contiguous_iterator.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2018-2020, Intel Corporation
+ * Copyright 2018-2021, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -245,7 +245,7 @@ struct range_snapshotting_iterator
 	{
 		assert(data <= ptr);
 
-		if (snapshot_size > 0)
+		if (snapshot_size && ptr)
 			snapshot_range(ptr);
 	}
 

tests/ptr/ptr.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2019, Intel Corporation
+ * Copyright 2015-2021, Intel Corporation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -344,6 +344,38 @@ test_offset(nvobj::pool<root> &pop)
 		UT_ASSERT(0);
 	}
 }
+
+/*
+ * test_offset_with_alignment -- test offset calculation within a hierarchy of
+ * objects with different alignments
+ */
+void
+test_offset_alignment(nvobj::pool<root> &pop)
+{
+	struct A {
+		char a;
+	};
+
+	struct B {
+		uint64_t b;
+	};
+
+	struct C : public A, public B {
+		uint64_t c;
+	};
+
+	try {
+		nvobj::transaction::run(pop, [] {
+			auto cptr = nvobj::make_persistent<C>();
+			nvobj::persistent_ptr<B> bptr = cptr;
+			UT_ASSERT((bptr.raw().off - cptr.raw().off) ==
+				  alignof(B));
+			nvobj::delete_persistent<C>(cptr);
+		});
+	} catch (...) {
+		UT_ASSERT(0);
+	}
+}
 }
 
 int
@@ -370,6 +402,7 @@ main(int argc, char *argv[])
 	test_ptr_transactional(pop);
 	test_ptr_array(pop);
 	test_offset(pop);
+	test_offset_alignment(pop);
 
 	pop.close();