Author: gbiv Date: Thu Jul 25 15:23:40 2019 New Revision: 367067 URL: http://llvm.org/viewvc/llvm-project?rev=367067&view=rev Log: [Sema] add -Walloca to flag uses of `alloca`
This CL adds an optional warning to diagnose uses of the `__builtin_alloca` family of functions. The use of these functions is discouraged by many, so it seems like a good idea to allow clang to warn about it. Patch by Elaina Guan! Differential Revision: https://reviews.llvm.org/D64883 Added: cfe/trunk/test/Sema/warn-alloca.c Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td cfe/trunk/lib/Sema/SemaChecking.cpp Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=367067&r1=367066&r2=367067&view=diff ============================================================================== --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original) +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Thu Jul 25 15:23:40 2019 @@ -2779,6 +2779,11 @@ def err_no_accessor_for_property : Error 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">>; Modified: cfe/trunk/lib/Sema/SemaChecking.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=367067&r1=367066&r2=367067&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaChecking.cpp (original) +++ cfe/trunk/lib/Sema/SemaChecking.cpp Thu Jul 25 15:23:40 2019 @@ -1179,6 +1179,10 @@ Sema::CheckBuiltinFunctionCall(FunctionD 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: Added: cfe/trunk/test/Sema/warn-alloca.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/warn-alloca.c?rev=367067&view=auto ============================================================================== --- cfe/trunk/test/Sema/warn-alloca.c (added) +++ cfe/trunk/test/Sema/warn-alloca.c Thu Jul 25 15:23:40 2019 @@ -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@-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@-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 +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
