Author: baloghadamsoftware Date: Mon May 6 03:41:37 2019 New Revision: 360032
URL: http://llvm.org/viewvc/llvm-project?rev=360032&view=rev Log: [clang-tidy] Extend bugprone-sizeof-expression check to detect sizeof misuse in pointer arithmetic Some programmers tend to forget that subtracting two pointers results in the difference between them in number of elements of the pointee type instead of bytes. This leads to codes such as `size_t size = (p - q) / sizeof(int)` where `p` and `q` are of type `int*`. Or similarily, `if (p - q < buffer_size * sizeof(int)) { ... }`. This patch extends `bugprone-sizeof-expression` to detect such cases. Differential Revision: https://reviews.llvm.org/D61422 Modified: clang-tools-extra/trunk/clang-tidy/bugprone/SizeofExpressionCheck.cpp clang-tools-extra/trunk/test/clang-tidy/bugprone-sizeof-expression.cpp Modified: clang-tools-extra/trunk/clang-tidy/bugprone/SizeofExpressionCheck.cpp URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/bugprone/SizeofExpressionCheck.cpp?rev=360032&r1=360031&r2=360032&view=diff ============================================================================== --- clang-tools-extra/trunk/clang-tidy/bugprone/SizeofExpressionCheck.cpp (original) +++ clang-tools-extra/trunk/clang-tidy/bugprone/SizeofExpressionCheck.cpp Mon May 6 03:41:37 2019 @@ -84,8 +84,11 @@ void SizeofExpressionCheck::registerMatc const auto IntegerCallExpr = expr(ignoringParenImpCasts( callExpr(anyOf(hasType(isInteger()), hasType(enumType())), unless(isInTemplateInstantiation())))); - const auto SizeOfExpr = - expr(anyOf(sizeOfExpr(has(type())), sizeOfExpr(has(expr())))); + const auto SizeOfExpr = expr(anyOf( + sizeOfExpr( + has(hasUnqualifiedDesugaredType(type().bind("sizeof-arg-type")))), + sizeOfExpr(has(expr(hasType( + hasUnqualifiedDesugaredType(type().bind("sizeof-arg-type")))))))); const auto SizeOfZero = expr( sizeOfExpr(has(ignoringParenImpCasts(expr(integerLiteral(equals(0))))))); @@ -209,6 +212,36 @@ void SizeofExpressionCheck::registerMatc hasSizeOfDescendant(8, expr(SizeOfExpr, unless(SizeOfZero)))))))) .bind("sizeof-sizeof-expr"), this); + + // Detect sizeof in pointer aritmetic like: N * sizeof(S) == P1 - P2 or + // (P1 - P2) / sizeof(S) where P1 and P2 are pointers to type S. + const auto PtrDiffExpr = binaryOperator( + hasOperatorName("-"), + hasLHS(expr(hasType(hasUnqualifiedDesugaredType(pointerType(pointee( + hasUnqualifiedDesugaredType(type().bind("left-ptr-type")))))))), + hasRHS(expr(hasType(hasUnqualifiedDesugaredType(pointerType(pointee( + hasUnqualifiedDesugaredType(type().bind("right-ptr-type"))))))))); + + Finder->addMatcher( + binaryOperator( + anyOf(hasOperatorName("=="), hasOperatorName("!="), + hasOperatorName("<"), hasOperatorName("<="), + hasOperatorName(">"), hasOperatorName(">="), + hasOperatorName("+"), hasOperatorName("-")), + hasEitherOperand(expr(anyOf( + ignoringParenImpCasts(SizeOfExpr), + ignoringParenImpCasts(binaryOperator( + hasOperatorName("*"), + hasEitherOperand(ignoringParenImpCasts(SizeOfExpr))))))), + hasEitherOperand(ignoringParenImpCasts(PtrDiffExpr))) + .bind("sizeof-in-ptr-arithmetic-mul"), + this); + + Finder->addMatcher(binaryOperator(hasOperatorName("/"), + hasLHS(ignoringParenImpCasts(PtrDiffExpr)), + hasRHS(ignoringParenImpCasts(SizeOfExpr))) + .bind("sizeof-in-ptr-arithmetic-div"), + this); } void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) { @@ -275,6 +308,26 @@ void SizeofExpressionCheck::check(const } else if (const auto *E = Result.Nodes.getNodeAs<Expr>("sizeof-multiply-sizeof")) { diag(E->getBeginLoc(), "suspicious 'sizeof' by 'sizeof' multiplication"); + } else if (const auto *E = + Result.Nodes.getNodeAs<Expr>("sizeof-in-ptr-arithmetic-mul")) { + const auto *LPtrTy = Result.Nodes.getNodeAs<Type>("left-ptr-type"); + const auto *RPtrTy = Result.Nodes.getNodeAs<Type>("right-ptr-type"); + const auto *SizeofArgTy = Result.Nodes.getNodeAs<Type>("sizeof-arg-type"); + + if ((LPtrTy == RPtrTy) && (LPtrTy == SizeofArgTy)) { + diag(E->getBeginLoc(), "suspicious usage of 'sizeof(...)' in " + "pointer arithmetic"); + } + } else if (const auto *E = + Result.Nodes.getNodeAs<Expr>("sizeof-in-ptr-arithmetic-div")) { + const auto *LPtrTy = Result.Nodes.getNodeAs<Type>("left-ptr-type"); + const auto *RPtrTy = Result.Nodes.getNodeAs<Type>("right-ptr-type"); + const auto *SizeofArgTy = Result.Nodes.getNodeAs<Type>("sizeof-arg-type"); + + if ((LPtrTy == RPtrTy) && (LPtrTy == SizeofArgTy)) { + diag(E->getBeginLoc(), "suspicious usage of 'sizeof(...)' in " + "pointer arithmetic"); + } } } Modified: clang-tools-extra/trunk/test/clang-tidy/bugprone-sizeof-expression.cpp URL: http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/bugprone-sizeof-expression.cpp?rev=360032&r1=360031&r2=360032&view=diff ============================================================================== --- clang-tools-extra/trunk/test/clang-tidy/bugprone-sizeof-expression.cpp (original) +++ clang-tools-extra/trunk/test/clang-tidy/bugprone-sizeof-expression.cpp Mon May 6 03:41:37 2019 @@ -231,6 +231,35 @@ int Test5() { return sum; } +int Test6() { + int sum = 0; + + struct S A = AsStruct(), B = AsStruct(); + struct S *P = &A, *Q = &B; + sum += sizeof(struct S) == P - Q; + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += 5 * sizeof(S) != P - Q; + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += sizeof(S) < P - Q; + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += 5 * sizeof(S) <= P - Q; + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += 5 * sizeof(*P) >= P - Q; + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += Q - P > 3 * sizeof(*P); + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += sizeof(S) + (P - Q); + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += 5 * sizeof(S) - (P - Q); + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += (P - Q) / sizeof(S); + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + sum += (P - Q) / sizeof(*Q); + // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic + + return sum; +} + int ValidExpressions() { int A[] = {1, 2, 3, 4}; static const char str[] = "hello"; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits