# HG changeset patch
# User Chris Peterson <cpeterson@mozilla.com>
# Date 1531634860 25200
#      Sat Jul 14 23:07:40 2018 -0700
# Node ID 138f27a016f6dd7dde91c6d8b66c3da179dc6e06
# Parent  cb66954c173fce66cfc4b22c34098cd8170eb32e
Bug 1475882 - clang-analyzer: Enable clang-analyzer-cplusplus.NewDelete check. r=andi

Check for double-free, use-after-free and offset problems involving C++ delete. There are currently no clang-analyzer-cplusplus.NewDelete warnings in mozilla-central!

https://clang-analyzer.llvm.org/available_checks.html

MozReview-Commit-ID: 9sVp4fc4JTj

diff --git a/tools/clang-tidy/config.yaml b/tools/clang-tidy/config.yaml
--- a/tools/clang-tidy/config.yaml
+++ b/tools/clang-tidy/config.yaml
@@ -6,16 +6,18 @@ target: obj-x86_64-pc-linux-gnu
 platforms:
   - macosx64
   - linux64
   - win64
   - win32
 clang_checkers:
   - name: -*
     publish: !!bool no
+  - name: clang-analyzer-cplusplus.NewDelete
+    publish: !!bool yes
   - name: clang-analyzer-deadcode.DeadStores
     publish: !!bool yes
   - name: clang-analyzer-security.FloatLoopCounter
     publish: !!bool yes
   - name: clang-analyzer-security.insecureAPI.getpw
     publish: !!bool yes
   # We don't add clang-analyzer-security.insecureAPI.gets here; it's deprecated.
   - name: clang-analyzer-security.insecureAPI.mkstemp
diff --git a/tools/clang-tidy/test/clang-analyzer-cplusplus.NewDelete.cpp b/tools/clang-tidy/test/clang-analyzer-cplusplus.NewDelete.cpp
new file mode 100644
--- /dev/null
+++ b/tools/clang-tidy/test/clang-analyzer-cplusplus.NewDelete.cpp
@@ -0,0 +1,50 @@
+// https://clang-analyzer.llvm.org/available_checks.html
+
+void use(int *p);
+
+void test_use_parameter_after_delete(int *p)
+{
+  delete p;
+  use(p); // warning: use after free
+}
+
+class SomeClass {
+public:
+  void f();
+};
+
+void test_use_local_after_delete()
+{
+  SomeClass *c = new SomeClass;
+  delete c;
+  c->f(); // warning: use after free
+}
+
+// XXX clang documentation says this should cause a warning but it doesn't!
+void test_delete_alloca()
+{
+  int *p = (int *)__builtin_alloca(sizeof(int));
+  delete p; // NO warning: deleting memory allocated by alloca
+}
+
+void test_double_free()
+{
+  int *p = new int;
+  delete p;
+  delete p; // warning: attempt to free released
+}
+
+void test_delete_local()
+{
+  int i;
+  delete &i; // warning: delete address of local
+}
+
+// XXX clang documentation says this should cause a warning but it doesn't!
+void test_delete_offset()
+{
+  int *p = new int[1];
+  delete[] (++p);
+    // NO warning: argument to 'delete[]' is offset by 4 bytes
+    // from the start of memory allocated by 'new[]'
+}
diff --git a/tools/clang-tidy/test/clang-analyzer-cplusplus.NewDelete.json b/tools/clang-tidy/test/clang-analyzer-cplusplus.NewDelete.json
new file mode 100644
--- /dev/null
+++ b/tools/clang-tidy/test/clang-analyzer-cplusplus.NewDelete.json
@@ -0,0 +1,1 @@
+"[[\"warning\", \"Use of memory after it is freed\", \"clang-analyzer-cplusplus.NewDelete\"], [\"warning\", \"Use of memory after it is freed\", \"clang-analyzer-cplusplus.NewDelete\"], [\"warning\", \"Attempt to free released memory\", \"clang-analyzer-cplusplus.NewDelete\"], [\"warning\", \"Argument to 'delete' is the address of the local variable 'i', which is not memory allocated by 'new'\", \"clang-analyzer-cplusplus.NewDelete\"]]"
\ No newline at end of file