Author: Bill Wendling Date: 2022-04-16T23:24:48-07:00 New Revision: 7f31b4a917d8cc13df5eac4b7f0520639c3a8fff
URL: https://github.com/llvm/llvm-project/commit/7f31b4a917d8cc13df5eac4b7f0520639c3a8fff DIFF: https://github.com/llvm/llvm-project/commit/7f31b4a917d8cc13df5eac4b7f0520639c3a8fff.diff LOG: [randstruct] Enforce using a designated init for a randomized struct A randomized structure needs to use a designated or default initializer. Using a non-designated initializer will result in values being assigned to the wrong fields. Differential Revision: https://reviews.llvm.org/D123763 Added: clang/test/Sema/init-randomized-struct.c Modified: clang/include/clang/Basic/DiagnosticSemaKinds.td clang/lib/Sema/SemaInit.cpp Removed: ################################################################################ diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index a14194d271a71..e79a40d62381f 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -11602,7 +11602,9 @@ def err_hlsl_pointers_unsupported : Error< def err_hlsl_operator_unsupported : Error< "the '%select{&|*|->}0' operator is unsupported in HLSL">; -// Layout randomization warning. +// Layout randomization diagnostics. +def err_non_designated_init_used : Error< + "a randomized struct can only be initialized with a designated initializer">; def err_cast_from_randomized_struct : Error< "casting from randomized structure pointer type %0 to %1">; } // end of sema component. diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp index c3bbefbaaed1b..233be547bf118 100644 --- a/clang/lib/Sema/SemaInit.cpp +++ b/clang/lib/Sema/SemaInit.cpp @@ -2123,6 +2123,7 @@ void InitListChecker::CheckStructUnionTypes( // worthwhile to skip over the rest of the initializer, though. RecordDecl *RD = DeclType->castAs<RecordType>()->getDecl(); RecordDecl::field_iterator FieldEnd = RD->field_end(); + size_t NumRecordFields = std::distance(RD->field_begin(), RD->field_end()); bool CheckForMissingFields = !IList->isIdiomaticZeroInitializer(SemaRef.getLangOpts()); bool HasDesignatedInit = false; @@ -2172,6 +2173,35 @@ void InitListChecker::CheckStructUnionTypes( break; } + // Check if this is an initializer of forms: + // + // struct foo f = {}; + // struct foo g = {0}; + // + // These are okay for randomized structures. [C99 6.7.8p19] + // + // Also, if there is only one element in the structure, we allow something + // like this, because it's really not randomized in the tranditional sense. + // + // struct foo h = {bar}; + auto IsZeroInitializer = [&](const Expr *I) { + if (IList->getNumInits() == 1) { + if (NumRecordFields == 1) + return true; + if (const auto *IL = dyn_cast<IntegerLiteral>(I)) + return IL->getValue().isZero(); + } + return false; + }; + + // Don't allow non-designated initializers on randomized structures. + if (RD->isRandomized() && !IsZeroInitializer(Init)) { + if (!VerifyOnly) + SemaRef.Diag(InitLoc, diag::err_non_designated_init_used); + hadError = true; + break; + } + // We've already initialized a member of a union. We're done. if (InitializedSomething && DeclType->isUnionType()) break; diff --git a/clang/test/Sema/init-randomized-struct.c b/clang/test/Sema/init-randomized-struct.c new file mode 100644 index 0000000000000..60403a91a547b --- /dev/null +++ b/clang/test/Sema/init-randomized-struct.c @@ -0,0 +1,57 @@ +// RUN: %clang_cc1 -triple=x86_64-unknown-linux -frandomize-layout-seed=1234567890abcdef \ +// RUN: -verify -fsyntax-only -Werror %s + +// Initializing a randomized structure requires a designated initializer, +// otherwise the element ordering will be off. The only exceptions to this rule +// are: +// +// - A structure with only one element, and +// - A structure initialized with "{0}". +// +// These are well-defined situations where the field ordering doesn't affect +// the result. + +typedef void (*func_ptr)(); + +void foo(void); +void bar(void); +void baz(void); +void gaz(void); + +struct test { + func_ptr a; + func_ptr b; + func_ptr c; + func_ptr d; + func_ptr e; + func_ptr f; + func_ptr g; +} __attribute__((randomize_layout)); + +struct test t1 = {}; // This should be fine per WG14 N2900 (in C23) + our extension handling of it in earlier modes +struct test t2 = { 0 }; // This should also be fine per C99 6.7.8p19 +struct test t3 = { .f = baz, .b = bar, .g = gaz, .a = foo }; // Okay +struct test t4 = { .a = foo, bar, baz }; // expected-error {{a randomized struct can only be initialized with a designated initializer}} + +struct other_test { + func_ptr a; + func_ptr b[3]; + func_ptr c; +} __attribute__((randomize_layout)); + +struct other_test t5 = { .a = foo, .b[0] = foo }; // Okay +struct other_test t6 = { .a = foo, .b[0] = foo, bar, baz }; // Okay +struct other_test t7 = { .a = foo, .b = { foo, bar, baz } }; // Okay +struct other_test t8 = { baz, bar, gaz, foo }; // expected-error {{a randomized struct can only be initialized with a designated initializer}} +struct other_test t9 = { .a = foo, .b[0] = foo, bar, baz, gaz }; // expected-error {{a randomized struct can only be initialized with a designated initializer}} + +struct empty_test { +} __attribute__((randomize_layout)); + +struct empty_test t10 = {}; // Okay + +struct degen_test { + func_ptr a; +} __attribute__((randomize_layout)); + +struct degen_test t11 = { foo }; // Okay _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
