From: Martin Liska <mliska@suse.cz>
Date: Wed, 15 Nov 2017 07:01:01 +0000 (+0100)
Subject: Zero vptr in dtor for -fsanitize=vptr.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=896f6b3dfa6fb337109f97bed8d74c1e030c965e;p=gcc.git

Zero vptr in dtor for -fsanitize=vptr.

2017-11-15  Martin Liska  <mliska@suse.cz>

	* decl.c (begin_destructor_body): In case of VPTR sanitization
	(with disabled recovery), zero vptr in order to catch virtual calls
	after lifetime of an object.
2017-11-15  Martin Liska  <mliska@suse.cz>

	* g++.dg/ubsan/vptr-12.C: New test.

From-SVN: r254754
---

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 8ba5b78aac2..578299ef0e2 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2017-11-15  Martin Liska  <mliska@suse.cz>
+
+	* decl.c (begin_destructor_body): In case of VPTR sanitization
+	(with disabled recovery), zero vptr in order to catch virtual calls
+	after lifetime of an object.
+
 2017-11-14  Jason Merrill  <jason@redhat.com>
 
 	Use GTY((cache)) on some hash tables.
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index c4eb28d14e2..041893db937 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -15246,7 +15246,26 @@ begin_destructor_body (void)
       if (flag_lifetime_dse
 	  /* Clobbering an empty base is harmful if it overlays real data.  */
 	  && !is_empty_class (current_class_type))
-	finish_decl_cleanup (NULL_TREE, build_clobber_this ());
+      {
+	if (sanitize_flags_p (SANITIZE_VPTR)
+	    && (flag_sanitize_recover & SANITIZE_VPTR) == 0
+	    && TYPE_CONTAINS_VPTR_P (current_class_type))
+	  {
+	    tree binfo = TYPE_BINFO (current_class_type);
+	    tree ref
+	      = cp_build_indirect_ref (current_class_ptr, RO_NULL,
+				       tf_warning_or_error);
+
+	    tree vtbl_ptr = build_vfield_ref (ref, TREE_TYPE (binfo));
+	    tree vtbl = build_zero_cst (TREE_TYPE (vtbl_ptr));
+	    tree stmt = cp_build_modify_expr (input_location, vtbl_ptr,
+					      NOP_EXPR, vtbl,
+					      tf_warning_or_error);
+	    finish_decl_cleanup (NULL_TREE, stmt);
+	  }
+	else
+	  finish_decl_cleanup (NULL_TREE, build_clobber_this ());
+      }
 
       /* And insert cleanups for our bases and members so that they
 	 will be properly destroyed if we throw.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1cd0070c82e..fd2b5d049ea 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2017-11-15  Martin Liska  <mliska@suse.cz>
+
+	* g++.dg/ubsan/vptr-12.C: New test.
+
 2017-11-15  Joseph Myers  <joseph@codesourcery.com>
 
 	PR c/81156
diff --git a/gcc/testsuite/g++.dg/ubsan/vptr-12.C b/gcc/testsuite/g++.dg/ubsan/vptr-12.C
new file mode 100644
index 00000000000..f23bbc3fd10
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ubsan/vptr-12.C
@@ -0,0 +1,22 @@
+// { dg-do run }
+// { dg-shouldfail "ubsan" }
+// { dg-options "-fsanitize=vptr -fno-sanitize-recover=vptr" }
+
+struct MyClass
+{
+  virtual ~MyClass () {}
+  virtual void Doit () {}
+};
+
+int
+main ()
+{
+  MyClass *c = new MyClass;
+  c->~MyClass ();
+  c->Doit ();
+
+  return 0;
+}
+
+// { dg-output "\[^\n\r]*vptr-12.C:16:\[0-9]*: runtime error: member call on address 0x\[0-9a-fA-F]* which does not point to an object of type 'MyClass'(\n|\r\n|\r)" }
+// { dg-output "0x\[0-9a-fA-F]*: note: object has invalid vptr" }