[PATCH] D64883: Add new warning -Walloca for use of builtin alloca function

[George Burgess IV via Phabricator via cfe-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL367067: [Sema] add -Walloca to flag uses of `alloca` (authored by gbiv, committed by ).
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Changed prior to commit:
  https://reviews.llvm.org/D64883?vs=211816&id=211837#toc

Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D64883/new/

https://reviews.llvm.org/D64883

Files:
  cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
  cfe/trunk/lib/Sema/SemaChecking.cpp
  cfe/trunk/test/Sema/warn-alloca.c


Index: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2779,6 +2779,11 @@
 def err_cannot_find_suitable_accessor : Error<
   "cannot find suitable %select{getter|setter}0 for property %1">;
 
+def warn_alloca : Warning<
+  "use of function %0 is discouraged; there is no way to check for failure but "
+  "failure may still occur, resulting in a possibly exploitable security vulnerability">,
+  InGroup<DiagGroup<"alloca">>, DefaultIgnore;
+
 def warn_alloca_align_alignof : Warning<
   "second argument to __builtin_alloca_with_align is supposed to be in bits">,
   InGroup<DiagGroup<"alloca-with-align-alignof">>;
Index: cfe/trunk/test/Sema/warn-alloca.c
===================================================================
--- cfe/trunk/test/Sema/warn-alloca.c
+++ cfe/trunk/test/Sema/warn-alloca.c
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -DSILENCE -fsyntax-only -verify -Wall %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Walloca %s
+
+#ifdef SILENCE
+  // expected-no-diagnostics
+#endif
+
+void test1(int a) {
+  __builtin_alloca(a);
+#ifndef SILENCE
+  // expected-warning at -2 {{use of function '__builtin_alloca' is discouraged; there is no way to check for failure but failure may still occur, resulting in a possibly exploitable security vulnerability}}
+#endif
+}
+
+void test2(int a) {
+  __builtin_alloca_with_align(a, 32);
+#ifndef SILENCE
+  // expected-warning at -2 {{use of function '__builtin_alloca_with_align' is discouraged; there is no way to check for failure but failure may still occur, resulting in a possibly exploitable security vulnerability}}
+#endif
+}
Index: cfe/trunk/lib/Sema/SemaChecking.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp
+++ cfe/trunk/lib/Sema/SemaChecking.cpp
@@ -1179,6 +1179,10 @@
   case Builtin::BI__builtin_alloca_with_align:
     if (SemaBuiltinAllocaWithAlign(TheCall))
       return ExprError();
+    LLVM_FALLTHROUGH;
+  case Builtin::BI__builtin_alloca:
+    Diag(TheCall->getBeginLoc(), diag::warn_alloca)
+        << TheCall->getDirectCallee();
     break;
   case Builtin::BI__assume:
   case Builtin::BI__builtin_assume:


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