1 // SValBuilder.cpp - Basic class for all SValBuilder implementations -*- C++ -*- 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines SValBuilder, the base class for all (complete) SValBuilder 11 // implementations. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "clang/AST/ExprCXX.h" 16 #include "clang/AST/DeclCXX.h" 17 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h" 18 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h" 20 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h" 21 #include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h" 22 23 using namespace clang; 24 using namespace ento; 25 26 //===----------------------------------------------------------------------===// 27 // Basic SVal creation. 28 //===----------------------------------------------------------------------===// 29 30 void SValBuilder::anchor() { } 31 32 DefinedOrUnknownSVal SValBuilder::makeZeroVal(QualType type) { 33 if (Loc::isLocType(type)) 34 return makeNull(); 35 36 if (type->isIntegerType()) 37 return makeIntVal(0, type); 38 39 // FIXME: Handle floats. 40 // FIXME: Handle structs. 41 return UnknownVal(); 42 } 43 44 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op, 45 const llvm::APSInt& rhs, QualType type) { 46 // The Environment ensures we always get a persistent APSInt in 47 // BasicValueFactory, so we don't need to get the APSInt from 48 // BasicValueFactory again. 49 assert(lhs); 50 assert(!Loc::isLocType(type)); 51 return nonloc::SymbolVal(SymMgr.getSymIntExpr(lhs, op, rhs, type)); 52 } 53 54 NonLoc SValBuilder::makeNonLoc(const llvm::APSInt& lhs, 55 BinaryOperator::Opcode op, const SymExpr *rhs, 56 QualType type) { 57 assert(rhs); 58 assert(!Loc::isLocType(type)); 59 return nonloc::SymbolVal(SymMgr.getIntSymExpr(lhs, op, rhs, type)); 60 } 61 62 NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op, 63 const SymExpr *rhs, QualType type) { 64 assert(lhs && rhs); 65 assert(!Loc::isLocType(type)); 66 return nonloc::SymbolVal(SymMgr.getSymSymExpr(lhs, op, rhs, type)); 67 } 68 69 NonLoc SValBuilder::makeNonLoc(const SymExpr *operand, 70 QualType fromTy, QualType toTy) { 71 assert(operand); 72 assert(!Loc::isLocType(toTy)); 73 return nonloc::SymbolVal(SymMgr.getCastSymbol(operand, fromTy, toTy)); 74 } 75 76 SVal SValBuilder::convertToArrayIndex(SVal val) { 77 if (val.isUnknownOrUndef()) 78 return val; 79 80 // Common case: we have an appropriately sized integer. 81 if (nonloc::ConcreteInt* CI = dyn_cast<nonloc::ConcreteInt>(&val)) { 82 const llvm::APSInt& I = CI->getValue(); 83 if (I.getBitWidth() == ArrayIndexWidth && I.isSigned()) 84 return val; 85 } 86 87 return evalCastFromNonLoc(cast<NonLoc>(val), ArrayIndexTy); 88 } 89 90 nonloc::ConcreteInt SValBuilder::makeBoolVal(const CXXBoolLiteralExpr *boolean){ 91 return makeTruthVal(boolean->getValue()); 92 } 93 94 DefinedOrUnknownSVal 95 SValBuilder::getRegionValueSymbolVal(const TypedValueRegion* region) { 96 QualType T = region->getValueType(); 97 98 if (!SymbolManager::canSymbolicate(T)) 99 return UnknownVal(); 100 101 SymbolRef sym = SymMgr.getRegionValueSymbol(region); 102 103 if (Loc::isLocType(T)) 104 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 105 106 return nonloc::SymbolVal(sym); 107 } 108 109 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *symbolTag, 110 const Expr *expr, 111 const LocationContext *LCtx, 112 unsigned count) { 113 QualType T = expr->getType(); 114 return conjureSymbolVal(symbolTag, expr, LCtx, T, count); 115 } 116 117 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const void *symbolTag, 118 const Expr *expr, 119 const LocationContext *LCtx, 120 QualType type, 121 unsigned count) { 122 if (!SymbolManager::canSymbolicate(type)) 123 return UnknownVal(); 124 125 SymbolRef sym = SymMgr.conjureSymbol(expr, LCtx, type, count, symbolTag); 126 127 if (Loc::isLocType(type)) 128 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 129 130 return nonloc::SymbolVal(sym); 131 } 132 133 134 DefinedOrUnknownSVal SValBuilder::conjureSymbolVal(const Stmt *stmt, 135 const LocationContext *LCtx, 136 QualType type, 137 unsigned visitCount) { 138 if (!SymbolManager::canSymbolicate(type)) 139 return UnknownVal(); 140 141 SymbolRef sym = SymMgr.conjureSymbol(stmt, LCtx, type, visitCount); 142 143 if (Loc::isLocType(type)) 144 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 145 146 return nonloc::SymbolVal(sym); 147 } 148 149 DefinedOrUnknownSVal 150 SValBuilder::getConjuredHeapSymbolVal(const Expr *E, 151 const LocationContext *LCtx, 152 unsigned VisitCount) { 153 QualType T = E->getType(); 154 assert(Loc::isLocType(T)); 155 assert(SymbolManager::canSymbolicate(T)); 156 157 SymbolRef sym = SymMgr.conjureSymbol(E, LCtx, T, VisitCount); 158 return loc::MemRegionVal(MemMgr.getSymbolicHeapRegion(sym)); 159 } 160 161 DefinedSVal SValBuilder::getMetadataSymbolVal(const void *symbolTag, 162 const MemRegion *region, 163 const Expr *expr, QualType type, 164 unsigned count) { 165 assert(SymbolManager::canSymbolicate(type) && "Invalid metadata symbol type"); 166 167 SymbolRef sym = 168 SymMgr.getMetadataSymbol(region, expr, type, count, symbolTag); 169 170 if (Loc::isLocType(type)) 171 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 172 173 return nonloc::SymbolVal(sym); 174 } 175 176 DefinedOrUnknownSVal 177 SValBuilder::getDerivedRegionValueSymbolVal(SymbolRef parentSymbol, 178 const TypedValueRegion *region) { 179 QualType T = region->getValueType(); 180 181 if (!SymbolManager::canSymbolicate(T)) 182 return UnknownVal(); 183 184 SymbolRef sym = SymMgr.getDerivedSymbol(parentSymbol, region); 185 186 if (Loc::isLocType(T)) 187 return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym)); 188 189 return nonloc::SymbolVal(sym); 190 } 191 192 DefinedSVal SValBuilder::getFunctionPointer(const FunctionDecl *func) { 193 return loc::MemRegionVal(MemMgr.getFunctionTextRegion(func)); 194 } 195 196 DefinedSVal SValBuilder::getBlockPointer(const BlockDecl *block, 197 CanQualType locTy, 198 const LocationContext *locContext) { 199 const BlockTextRegion *BC = 200 MemMgr.getBlockTextRegion(block, locTy, locContext->getAnalysisDeclContext()); 201 const BlockDataRegion *BD = MemMgr.getBlockDataRegion(BC, locContext); 202 return loc::MemRegionVal(BD); 203 } 204 205 /// Return a memory region for the 'this' object reference. 206 loc::MemRegionVal SValBuilder::getCXXThis(const CXXMethodDecl *D, 207 const StackFrameContext *SFC) { 208 return loc::MemRegionVal(getRegionManager(). 209 getCXXThisRegion(D->getThisType(getContext()), SFC)); 210 } 211 212 /// Return a memory region for the 'this' object reference. 213 loc::MemRegionVal SValBuilder::getCXXThis(const CXXRecordDecl *D, 214 const StackFrameContext *SFC) { 215 const Type *T = D->getTypeForDecl(); 216 QualType PT = getContext().getPointerType(QualType(T, 0)); 217 return loc::MemRegionVal(getRegionManager().getCXXThisRegion(PT, SFC)); 218 } 219 220 //===----------------------------------------------------------------------===// 221 222 SVal SValBuilder::makeSymExprValNN(ProgramStateRef State, 223 BinaryOperator::Opcode Op, 224 NonLoc LHS, NonLoc RHS, 225 QualType ResultTy) { 226 if (!State->isTainted(RHS) && !State->isTainted(LHS)) 227 return UnknownVal(); 228 229 const SymExpr *symLHS = LHS.getAsSymExpr(); 230 const SymExpr *symRHS = RHS.getAsSymExpr(); 231 // TODO: When the Max Complexity is reached, we should conjure a symbol 232 // instead of generating an Unknown value and propagate the taint info to it. 233 const unsigned MaxComp = 10000; // 100000 28X 234 235 if (symLHS && symRHS && 236 (symLHS->computeComplexity() + symRHS->computeComplexity()) < MaxComp) 237 return makeNonLoc(symLHS, Op, symRHS, ResultTy); 238 239 if (symLHS && symLHS->computeComplexity() < MaxComp) 240 if (const nonloc::ConcreteInt *rInt = dyn_cast<nonloc::ConcreteInt>(&RHS)) 241 return makeNonLoc(symLHS, Op, rInt->getValue(), ResultTy); 242 243 if (symRHS && symRHS->computeComplexity() < MaxComp) 244 if (const nonloc::ConcreteInt *lInt = dyn_cast<nonloc::ConcreteInt>(&LHS)) 245 return makeNonLoc(lInt->getValue(), Op, symRHS, ResultTy); 246 247 return UnknownVal(); 248 } 249 250 251 SVal SValBuilder::evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op, 252 SVal lhs, SVal rhs, QualType type) { 253 254 if (lhs.isUndef() || rhs.isUndef()) 255 return UndefinedVal(); 256 257 if (lhs.isUnknown() || rhs.isUnknown()) 258 return UnknownVal(); 259 260 if (isa<Loc>(lhs)) { 261 if (isa<Loc>(rhs)) 262 return evalBinOpLL(state, op, cast<Loc>(lhs), cast<Loc>(rhs), type); 263 264 return evalBinOpLN(state, op, cast<Loc>(lhs), cast<NonLoc>(rhs), type); 265 } 266 267 if (isa<Loc>(rhs)) { 268 // Support pointer arithmetic where the addend is on the left 269 // and the pointer on the right. 270 assert(op == BO_Add); 271 272 // Commute the operands. 273 return evalBinOpLN(state, op, cast<Loc>(rhs), cast<NonLoc>(lhs), type); 274 } 275 276 return evalBinOpNN(state, op, cast<NonLoc>(lhs), cast<NonLoc>(rhs), type); 277 } 278 279 DefinedOrUnknownSVal SValBuilder::evalEQ(ProgramStateRef state, 280 DefinedOrUnknownSVal lhs, 281 DefinedOrUnknownSVal rhs) { 282 return cast<DefinedOrUnknownSVal>(evalBinOp(state, BO_EQ, lhs, rhs, 283 Context.IntTy)); 284 } 285 286 /// Recursively check if the pointer types are equal modulo const, volatile, 287 /// and restrict qualifiers. Assumes the input types are canonical. 288 /// TODO: This is based off of code in SemaCast; can we reuse it. 289 static bool haveSimilarTypes(ASTContext &Context, QualType T1, 290 QualType T2) { 291 while (Context.UnwrapSimilarPointerTypes(T1, T2)) { 292 Qualifiers Quals1, Quals2; 293 T1 = Context.getUnqualifiedArrayType(T1, Quals1); 294 T2 = Context.getUnqualifiedArrayType(T2, Quals2); 295 296 // Make sure that non cvr-qualifiers the other qualifiers (e.g., address 297 // spaces) are identical. 298 Quals1.removeCVRQualifiers(); 299 Quals2.removeCVRQualifiers(); 300 if (Quals1 != Quals2) 301 return false; 302 } 303 304 if (T1 != T2) 305 return false; 306 307 return true; 308 } 309 310 // FIXME: should rewrite according to the cast kind. 311 SVal SValBuilder::evalCast(SVal val, QualType castTy, QualType originalTy) { 312 castTy = Context.getCanonicalType(castTy); 313 originalTy = Context.getCanonicalType(originalTy); 314 if (val.isUnknownOrUndef() || castTy == originalTy) 315 return val; 316 317 // For const casts, just propagate the value. 318 if (!castTy->isVariableArrayType() && !originalTy->isVariableArrayType()) 319 if (haveSimilarTypes(Context, Context.getPointerType(castTy), 320 Context.getPointerType(originalTy))) 321 return val; 322 323 // Check for casts from pointers to integers. 324 if (castTy->isIntegerType() && Loc::isLocType(originalTy)) 325 return evalCastFromLoc(cast<Loc>(val), castTy); 326 327 // Check for casts from integers to pointers. 328 if (Loc::isLocType(castTy) && originalTy->isIntegerType()) { 329 if (nonloc::LocAsInteger *LV = dyn_cast<nonloc::LocAsInteger>(&val)) { 330 if (const MemRegion *R = LV->getLoc().getAsRegion()) { 331 StoreManager &storeMgr = StateMgr.getStoreManager(); 332 R = storeMgr.castRegion(R, castTy); 333 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal(); 334 } 335 return LV->getLoc(); 336 } 337 return dispatchCast(val, castTy); 338 } 339 340 // Just pass through function and block pointers. 341 if (originalTy->isBlockPointerType() || originalTy->isFunctionPointerType()) { 342 assert(Loc::isLocType(castTy)); 343 return val; 344 } 345 346 // Check for casts from array type to another type. 347 if (originalTy->isArrayType()) { 348 // We will always decay to a pointer. 349 val = StateMgr.ArrayToPointer(cast<Loc>(val)); 350 351 // Are we casting from an array to a pointer? If so just pass on 352 // the decayed value. 353 if (castTy->isPointerType() || castTy->isReferenceType()) 354 return val; 355 356 // Are we casting from an array to an integer? If so, cast the decayed 357 // pointer value to an integer. 358 assert(castTy->isIntegerType()); 359 360 // FIXME: Keep these here for now in case we decide soon that we 361 // need the original decayed type. 362 // QualType elemTy = cast<ArrayType>(originalTy)->getElementType(); 363 // QualType pointerTy = C.getPointerType(elemTy); 364 return evalCastFromLoc(cast<Loc>(val), castTy); 365 } 366 367 // Check for casts from a region to a specific type. 368 if (const MemRegion *R = val.getAsRegion()) { 369 // Handle other casts of locations to integers. 370 if (castTy->isIntegerType()) 371 return evalCastFromLoc(loc::MemRegionVal(R), castTy); 372 373 // FIXME: We should handle the case where we strip off view layers to get 374 // to a desugared type. 375 if (!Loc::isLocType(castTy)) { 376 // FIXME: There can be gross cases where one casts the result of a function 377 // (that returns a pointer) to some other value that happens to fit 378 // within that pointer value. We currently have no good way to 379 // model such operations. When this happens, the underlying operation 380 // is that the caller is reasoning about bits. Conceptually we are 381 // layering a "view" of a location on top of those bits. Perhaps 382 // we need to be more lazy about mutual possible views, even on an 383 // SVal? This may be necessary for bit-level reasoning as well. 384 return UnknownVal(); 385 } 386 387 // We get a symbolic function pointer for a dereference of a function 388 // pointer, but it is of function type. Example: 389 390 // struct FPRec { 391 // void (*my_func)(int * x); 392 // }; 393 // 394 // int bar(int x); 395 // 396 // int f1_a(struct FPRec* foo) { 397 // int x; 398 // (*foo->my_func)(&x); 399 // return bar(x)+1; // no-warning 400 // } 401 402 assert(Loc::isLocType(originalTy) || originalTy->isFunctionType() || 403 originalTy->isBlockPointerType() || castTy->isReferenceType()); 404 405 StoreManager &storeMgr = StateMgr.getStoreManager(); 406 407 // Delegate to store manager to get the result of casting a region to a 408 // different type. If the MemRegion* returned is NULL, this expression 409 // Evaluates to UnknownVal. 410 R = storeMgr.castRegion(R, castTy); 411 return R ? SVal(loc::MemRegionVal(R)) : UnknownVal(); 412 } 413 414 return dispatchCast(val, castTy); 415 } 416
