Bug Summary

File:tools/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp
Warning:line 294, column 25
Called C++ object pointer is null

Annotated Source Code

Press '?' to see keyboard shortcuts

clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name CheckSecuritySyntaxOnly.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-eagerly-assume -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -relaxed-aliasing -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/tools/clang/lib/StaticAnalyzer/Checkers -I /build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/StaticAnalyzer/Checkers -I /build/llvm-toolchain-snapshot-7~svn338205/tools/clang/include -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn338205/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/x86_64-linux-gnu/c++/8 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/include -internal-externc-isystem /usr/lib/gcc/x86_64-linux-gnu/8/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn338205/build-llvm/tools/clang/lib/StaticAnalyzer/Checkers -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fno-common -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-07-29-043837-17923-1 -x c++ /build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp -faddrsig
1//==- CheckSecuritySyntaxOnly.cpp - Basic security checks --------*- 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 a set of flow-insensitive security checks.
11//
12//===----------------------------------------------------------------------===//
13
14#include "ClangSACheckers.h"
15#include "clang/AST/StmtVisitor.h"
16#include "clang/Analysis/AnalysisDeclContext.h"
17#include "clang/Basic/TargetInfo.h"
18#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
19#include "clang/StaticAnalyzer/Core/Checker.h"
20#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"
21#include "llvm/ADT/SmallString.h"
22#include "llvm/ADT/StringSwitch.h"
23#include "llvm/Support/raw_ostream.h"
24
25using namespace clang;
26using namespace ento;
27
28static bool isArc4RandomAvailable(const ASTContext &Ctx) {
29 const llvm::Triple &T = Ctx.getTargetInfo().getTriple();
30 return T.getVendor() == llvm::Triple::Apple ||
31 T.getOS() == llvm::Triple::CloudABI ||
32 T.getOS() == llvm::Triple::FreeBSD ||
33 T.getOS() == llvm::Triple::NetBSD ||
34 T.getOS() == llvm::Triple::OpenBSD ||
35 T.getOS() == llvm::Triple::DragonFly;
36}
37
38namespace {
39struct ChecksFilter {
40 DefaultBool check_bcmp;
41 DefaultBool check_bcopy;
42 DefaultBool check_bzero;
43 DefaultBool check_gets;
44 DefaultBool check_getpw;
45 DefaultBool check_mktemp;
46 DefaultBool check_mkstemp;
47 DefaultBool check_strcpy;
48 DefaultBool check_rand;
49 DefaultBool check_vfork;
50 DefaultBool check_FloatLoopCounter;
51 DefaultBool check_UncheckedReturn;
52
53 CheckName checkName_bcmp;
54 CheckName checkName_bcopy;
55 CheckName checkName_bzero;
56 CheckName checkName_gets;
57 CheckName checkName_getpw;
58 CheckName checkName_mktemp;
59 CheckName checkName_mkstemp;
60 CheckName checkName_strcpy;
61 CheckName checkName_rand;
62 CheckName checkName_vfork;
63 CheckName checkName_FloatLoopCounter;
64 CheckName checkName_UncheckedReturn;
65};
66
67class WalkAST : public StmtVisitor<WalkAST> {
68 BugReporter &BR;
69 AnalysisDeclContext* AC;
70 enum { num_setids = 6 };
71 IdentifierInfo *II_setid[num_setids];
72
73 const bool CheckRand;
74 const ChecksFilter &filter;
75
76public:
77 WalkAST(BugReporter &br, AnalysisDeclContext* ac,
78 const ChecksFilter &f)
79 : BR(br), AC(ac), II_setid(),
80 CheckRand(isArc4RandomAvailable(BR.getContext())),
81 filter(f) {}
82
83 // Statement visitor methods.
84 void VisitCallExpr(CallExpr *CE);
85 void VisitForStmt(ForStmt *S);
86 void VisitCompoundStmt (CompoundStmt *S);
87 void VisitStmt(Stmt *S) { VisitChildren(S); }
88
89 void VisitChildren(Stmt *S);
90
91 // Helpers.
92 bool checkCall_strCommon(const CallExpr *CE, const FunctionDecl *FD);
93
94 typedef void (WalkAST::*FnCheck)(const CallExpr *, const FunctionDecl *);
95
96 // Checker-specific methods.
97 void checkLoopConditionForFloat(const ForStmt *FS);
98 void checkCall_bcmp(const CallExpr *CE, const FunctionDecl *FD);
99 void checkCall_bcopy(const CallExpr *CE, const FunctionDecl *FD);
100 void checkCall_bzero(const CallExpr *CE, const FunctionDecl *FD);
101 void checkCall_gets(const CallExpr *CE, const FunctionDecl *FD);
102 void checkCall_getpw(const CallExpr *CE, const FunctionDecl *FD);
103 void checkCall_mktemp(const CallExpr *CE, const FunctionDecl *FD);
104 void checkCall_mkstemp(const CallExpr *CE, const FunctionDecl *FD);
105 void checkCall_strcpy(const CallExpr *CE, const FunctionDecl *FD);
106 void checkCall_strcat(const CallExpr *CE, const FunctionDecl *FD);
107 void checkCall_rand(const CallExpr *CE, const FunctionDecl *FD);
108 void checkCall_random(const CallExpr *CE, const FunctionDecl *FD);
109 void checkCall_vfork(const CallExpr *CE, const FunctionDecl *FD);
110 void checkUncheckedReturnValue(CallExpr *CE);
111};
112} // end anonymous namespace
113
114//===----------------------------------------------------------------------===//
115// AST walking.
116//===----------------------------------------------------------------------===//
117
118void WalkAST::VisitChildren(Stmt *S) {
119 for (Stmt *Child : S->children())
120 if (Child)
121 Visit(Child);
122}
123
124void WalkAST::VisitCallExpr(CallExpr *CE) {
125 // Get the callee.
126 const FunctionDecl *FD = CE->getDirectCallee();
127
128 if (!FD)
129 return;
130
131 // Get the name of the callee. If it's a builtin, strip off the prefix.
132 IdentifierInfo *II = FD->getIdentifier();
133 if (!II) // if no identifier, not a simple C function
134 return;
135 StringRef Name = II->getName();
136 if (Name.startswith("__builtin_"))
137 Name = Name.substr(10);
138
139 // Set the evaluation function by switching on the callee name.
140 FnCheck evalFunction = llvm::StringSwitch<FnCheck>(Name)
141 .Case("bcmp", &WalkAST::checkCall_bcmp)
142 .Case("bcopy", &WalkAST::checkCall_bcopy)
143 .Case("bzero", &WalkAST::checkCall_bzero)
144 .Case("gets", &WalkAST::checkCall_gets)
145 .Case("getpw", &WalkAST::checkCall_getpw)
146 .Case("mktemp", &WalkAST::checkCall_mktemp)
147 .Case("mkstemp", &WalkAST::checkCall_mkstemp)
148 .Case("mkdtemp", &WalkAST::checkCall_mkstemp)
149 .Case("mkstemps", &WalkAST::checkCall_mkstemp)
150 .Cases("strcpy", "__strcpy_chk", &WalkAST::checkCall_strcpy)
151 .Cases("strcat", "__strcat_chk", &WalkAST::checkCall_strcat)
152 .Case("drand48", &WalkAST::checkCall_rand)
153 .Case("erand48", &WalkAST::checkCall_rand)
154 .Case("jrand48", &WalkAST::checkCall_rand)
155 .Case("lrand48", &WalkAST::checkCall_rand)
156 .Case("mrand48", &WalkAST::checkCall_rand)
157 .Case("nrand48", &WalkAST::checkCall_rand)
158 .Case("lcong48", &WalkAST::checkCall_rand)
159 .Case("rand", &WalkAST::checkCall_rand)
160 .Case("rand_r", &WalkAST::checkCall_rand)
161 .Case("random", &WalkAST::checkCall_random)
162 .Case("vfork", &WalkAST::checkCall_vfork)
163 .Default(nullptr);
164
165 // If the callee isn't defined, it is not of security concern.
166 // Check and evaluate the call.
167 if (evalFunction)
168 (this->*evalFunction)(CE, FD);
169
170 // Recurse and check children.
171 VisitChildren(CE);
172}
173
174void WalkAST::VisitCompoundStmt(CompoundStmt *S) {
175 for (Stmt *Child : S->children())
176 if (Child) {
177 if (CallExpr *CE = dyn_cast<CallExpr>(Child))
178 checkUncheckedReturnValue(CE);
179 Visit(Child);
180 }
181}
182
183void WalkAST::VisitForStmt(ForStmt *FS) {
184 checkLoopConditionForFloat(FS);
1
Calling 'WalkAST::checkLoopConditionForFloat'
185
186 // Recurse and check children.
187 VisitChildren(FS);
188}
189
190//===----------------------------------------------------------------------===//
191// Check: floating poing variable used as loop counter.
192// Originally: <rdar://problem/6336718>
193// Implements: CERT security coding advisory FLP-30.
194//===----------------------------------------------------------------------===//
195
196static const DeclRefExpr*
197getIncrementedVar(const Expr *expr, const VarDecl *x, const VarDecl *y) {
198 expr = expr->IgnoreParenCasts();
199
200 if (const BinaryOperator *B = dyn_cast<BinaryOperator>(expr)) {
201 if (!(B->isAssignmentOp() || B->isCompoundAssignmentOp() ||
202 B->getOpcode() == BO_Comma))
203 return nullptr;
204
205 if (const DeclRefExpr *lhs = getIncrementedVar(B->getLHS(), x, y))
206 return lhs;
207
208 if (const DeclRefExpr *rhs = getIncrementedVar(B->getRHS(), x, y))
209 return rhs;
210
211 return nullptr;
212 }
213
214 if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(expr)) {
215 const NamedDecl *ND = DR->getDecl();
216 return ND == x || ND == y ? DR : nullptr;
217 }
218
219 if (const UnaryOperator *U = dyn_cast<UnaryOperator>(expr))
220 return U->isIncrementDecrementOp()
221 ? getIncrementedVar(U->getSubExpr(), x, y) : nullptr;
222
223 return nullptr;
224}
225
226/// CheckLoopConditionForFloat - This check looks for 'for' statements that
227/// use a floating point variable as a loop counter.
228/// CERT: FLP30-C, FLP30-CPP.
229///
230void WalkAST::checkLoopConditionForFloat(const ForStmt *FS) {
231 if (!filter.check_FloatLoopCounter)
2
Assuming the condition is false
3
Taking false branch
232 return;
233
234 // Does the loop have a condition?
235 const Expr *condition = FS->getCond();
236
237 if (!condition)
4
Assuming 'condition' is non-null
5
Taking false branch
238 return;
239
240 // Does the loop have an increment?
241 const Expr *increment = FS->getInc();
242
243 if (!increment)
6
Assuming 'increment' is non-null
7
Taking false branch
244 return;
245
246 // Strip away '()' and casts.
247 condition = condition->IgnoreParenCasts();
248 increment = increment->IgnoreParenCasts();
249
250 // Is the loop condition a comparison?
251 const BinaryOperator *B = dyn_cast<BinaryOperator>(condition);
252
253 if (!B)
8
Assuming 'B' is non-null
9
Taking false branch
254 return;
255
256 // Is this a comparison?
257 if (!(B->isRelationalOp() || B->isEqualityOp()))
10
Taking false branch
258 return;
259
260 // Are we comparing variables?
261 const DeclRefExpr *drLHS =
262 dyn_cast<DeclRefExpr>(B->getLHS()->IgnoreParenLValueCasts());
263 const DeclRefExpr *drRHS =
264 dyn_cast<DeclRefExpr>(B->getRHS()->IgnoreParenLValueCasts());
265
266 // Does at least one of the variables have a floating point type?
267 drLHS = drLHS && drLHS->getType()->isRealFloatingType() ? drLHS : nullptr;
11
Assuming 'drLHS' is non-null
12
Assuming the condition is true
13
'?' condition is true
268 drRHS = drRHS && drRHS->getType()->isRealFloatingType() ? drRHS : nullptr;
14
Null pointer value stored to 'drRHS'
269
270 if (!drLHS && !drRHS)
271 return;
272
273 const VarDecl *vdLHS = drLHS ? dyn_cast<VarDecl>(drLHS->getDecl()) : nullptr;
15
'?' condition is true
274 const VarDecl *vdRHS = drRHS ? dyn_cast<VarDecl>(drRHS->getDecl()) : nullptr;
16
'?' condition is false
275
276 if (!vdLHS && !vdRHS)
17
Assuming 'vdLHS' is non-null
277 return;
278
279 // Does either variable appear in increment?
280 const DeclRefExpr *drInc = getIncrementedVar(increment, vdLHS, vdRHS);
281
282 if (!drInc)
18
Assuming 'drInc' is non-null
19
Taking false branch
283 return;
284
285 // Emit the error. First figure out which DeclRefExpr in the condition
286 // referenced the compared variable.
287 assert(drInc->getDecl())(static_cast <bool> (drInc->getDecl()) ? void (0) : __assert_fail
("drInc->getDecl()", "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp"
, 287, __extension__ __PRETTY_FUNCTION__))
;
288 const DeclRefExpr *drCond = vdLHS == drInc->getDecl() ? drLHS : drRHS;
20
Assuming the condition is false
21
'?' condition is false
22
'drCond' initialized to a null pointer value
289
290 SmallVector<SourceRange, 2> ranges;
291 SmallString<256> sbuf;
292 llvm::raw_svector_ostream os(sbuf);
293
294 os << "Variable '" << drCond->getDecl()->getName()
23
Called C++ object pointer is null
295 << "' with floating point type '" << drCond->getType().getAsString()
296 << "' should not be used as a loop counter";
297
298 ranges.push_back(drCond->getSourceRange());
299 ranges.push_back(drInc->getSourceRange());
300
301 const char *bugType = "Floating point variable used as loop counter";
302
303 PathDiagnosticLocation FSLoc =
304 PathDiagnosticLocation::createBegin(FS, BR.getSourceManager(), AC);
305 BR.EmitBasicReport(AC->getDecl(), filter.checkName_FloatLoopCounter,
306 bugType, "Security", os.str(),
307 FSLoc, ranges);
308}
309
310//===----------------------------------------------------------------------===//
311// Check: Any use of bcmp.
312// CWE-477: Use of Obsolete Functions
313// bcmp was deprecated in POSIX.1-2008
314//===----------------------------------------------------------------------===//
315
316void WalkAST::checkCall_bcmp(const CallExpr *CE, const FunctionDecl *FD) {
317 if (!filter.check_bcmp)
318 return;
319
320 const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
321 if (!FPT)
322 return;
323
324 // Verify that the function takes three arguments.
325 if (FPT->getNumParams() != 3)
326 return;
327
328 for (int i = 0; i < 2; i++) {
329 // Verify the first and second argument type is void*.
330 const PointerType *PT = FPT->getParamType(i)->getAs<PointerType>();
331 if (!PT)
332 return;
333
334 if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().VoidTy)
335 return;
336 }
337
338 // Verify the third argument type is integer.
339 if (!FPT->getParamType(2)->isIntegralOrUnscopedEnumerationType())
340 return;
341
342 // Issue a warning.
343 PathDiagnosticLocation CELoc =
344 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
345 BR.EmitBasicReport(AC->getDecl(), filter.checkName_bcmp,
346 "Use of deprecated function in call to 'bcmp()'",
347 "Security",
348 "The bcmp() function is obsoleted by memcmp().",
349 CELoc, CE->getCallee()->getSourceRange());
350}
351
352//===----------------------------------------------------------------------===//
353// Check: Any use of bcopy.
354// CWE-477: Use of Obsolete Functions
355// bcopy was deprecated in POSIX.1-2008
356//===----------------------------------------------------------------------===//
357
358void WalkAST::checkCall_bcopy(const CallExpr *CE, const FunctionDecl *FD) {
359 if (!filter.check_bcopy)
360 return;
361
362 const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
363 if (!FPT)
364 return;
365
366 // Verify that the function takes three arguments.
367 if (FPT->getNumParams() != 3)
368 return;
369
370 for (int i = 0; i < 2; i++) {
371 // Verify the first and second argument type is void*.
372 const PointerType *PT = FPT->getParamType(i)->getAs<PointerType>();
373 if (!PT)
374 return;
375
376 if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().VoidTy)
377 return;
378 }
379
380 // Verify the third argument type is integer.
381 if (!FPT->getParamType(2)->isIntegralOrUnscopedEnumerationType())
382 return;
383
384 // Issue a warning.
385 PathDiagnosticLocation CELoc =
386 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
387 BR.EmitBasicReport(AC->getDecl(), filter.checkName_bcopy,
388 "Use of deprecated function in call to 'bcopy()'",
389 "Security",
390 "The bcopy() function is obsoleted by memcpy() "
391 "or memmove().",
392 CELoc, CE->getCallee()->getSourceRange());
393}
394
395//===----------------------------------------------------------------------===//
396// Check: Any use of bzero.
397// CWE-477: Use of Obsolete Functions
398// bzero was deprecated in POSIX.1-2008
399//===----------------------------------------------------------------------===//
400
401void WalkAST::checkCall_bzero(const CallExpr *CE, const FunctionDecl *FD) {
402 if (!filter.check_bzero)
403 return;
404
405 const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
406 if (!FPT)
407 return;
408
409 // Verify that the function takes two arguments.
410 if (FPT->getNumParams() != 2)
411 return;
412
413 // Verify the first argument type is void*.
414 const PointerType *PT = FPT->getParamType(0)->getAs<PointerType>();
415 if (!PT)
416 return;
417
418 if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().VoidTy)
419 return;
420
421 // Verify the second argument type is integer.
422 if (!FPT->getParamType(1)->isIntegralOrUnscopedEnumerationType())
423 return;
424
425 // Issue a warning.
426 PathDiagnosticLocation CELoc =
427 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
428 BR.EmitBasicReport(AC->getDecl(), filter.checkName_bzero,
429 "Use of deprecated function in call to 'bzero()'",
430 "Security",
431 "The bzero() function is obsoleted by memset().",
432 CELoc, CE->getCallee()->getSourceRange());
433}
434
435
436//===----------------------------------------------------------------------===//
437// Check: Any use of 'gets' is insecure.
438// Originally: <rdar://problem/6335715>
439// Implements (part of): 300-BSI (buildsecurityin.us-cert.gov)
440// CWE-242: Use of Inherently Dangerous Function
441//===----------------------------------------------------------------------===//
442
443void WalkAST::checkCall_gets(const CallExpr *CE, const FunctionDecl *FD) {
444 if (!filter.check_gets)
445 return;
446
447 const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
448 if (!FPT)
449 return;
450
451 // Verify that the function takes a single argument.
452 if (FPT->getNumParams() != 1)
453 return;
454
455 // Is the argument a 'char*'?
456 const PointerType *PT = FPT->getParamType(0)->getAs<PointerType>();
457 if (!PT)
458 return;
459
460 if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
461 return;
462
463 // Issue a warning.
464 PathDiagnosticLocation CELoc =
465 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
466 BR.EmitBasicReport(AC->getDecl(), filter.checkName_gets,
467 "Potential buffer overflow in call to 'gets'",
468 "Security",
469 "Call to function 'gets' is extremely insecure as it can "
470 "always result in a buffer overflow",
471 CELoc, CE->getCallee()->getSourceRange());
472}
473
474//===----------------------------------------------------------------------===//
475// Check: Any use of 'getpwd' is insecure.
476// CWE-477: Use of Obsolete Functions
477//===----------------------------------------------------------------------===//
478
479void WalkAST::checkCall_getpw(const CallExpr *CE, const FunctionDecl *FD) {
480 if (!filter.check_getpw)
481 return;
482
483 const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
484 if (!FPT)
485 return;
486
487 // Verify that the function takes two arguments.
488 if (FPT->getNumParams() != 2)
489 return;
490
491 // Verify the first argument type is integer.
492 if (!FPT->getParamType(0)->isIntegralOrUnscopedEnumerationType())
493 return;
494
495 // Verify the second argument type is char*.
496 const PointerType *PT = FPT->getParamType(1)->getAs<PointerType>();
497 if (!PT)
498 return;
499
500 if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
501 return;
502
503 // Issue a warning.
504 PathDiagnosticLocation CELoc =
505 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
506 BR.EmitBasicReport(AC->getDecl(), filter.checkName_getpw,
507 "Potential buffer overflow in call to 'getpw'",
508 "Security",
509 "The getpw() function is dangerous as it may overflow the "
510 "provided buffer. It is obsoleted by getpwuid().",
511 CELoc, CE->getCallee()->getSourceRange());
512}
513
514//===----------------------------------------------------------------------===//
515// Check: Any use of 'mktemp' is insecure. It is obsoleted by mkstemp().
516// CWE-377: Insecure Temporary File
517//===----------------------------------------------------------------------===//
518
519void WalkAST::checkCall_mktemp(const CallExpr *CE, const FunctionDecl *FD) {
520 if (!filter.check_mktemp) {
521 // Fall back to the security check of looking for enough 'X's in the
522 // format string, since that is a less severe warning.
523 checkCall_mkstemp(CE, FD);
524 return;
525 }
526
527 const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
528 if(!FPT)
529 return;
530
531 // Verify that the function takes a single argument.
532 if (FPT->getNumParams() != 1)
533 return;
534
535 // Verify that the argument is Pointer Type.
536 const PointerType *PT = FPT->getParamType(0)->getAs<PointerType>();
537 if (!PT)
538 return;
539
540 // Verify that the argument is a 'char*'.
541 if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
542 return;
543
544 // Issue a warning.
545 PathDiagnosticLocation CELoc =
546 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
547 BR.EmitBasicReport(AC->getDecl(), filter.checkName_mktemp,
548 "Potential insecure temporary file in call 'mktemp'",
549 "Security",
550 "Call to function 'mktemp' is insecure as it always "
551 "creates or uses insecure temporary file. Use 'mkstemp' "
552 "instead",
553 CELoc, CE->getCallee()->getSourceRange());
554}
555
556
557//===----------------------------------------------------------------------===//
558// Check: Use of 'mkstemp', 'mktemp', 'mkdtemp' should contain at least 6 X's.
559//===----------------------------------------------------------------------===//
560
561void WalkAST::checkCall_mkstemp(const CallExpr *CE, const FunctionDecl *FD) {
562 if (!filter.check_mkstemp)
563 return;
564
565 StringRef Name = FD->getIdentifier()->getName();
566 std::pair<signed, signed> ArgSuffix =
567 llvm::StringSwitch<std::pair<signed, signed> >(Name)
568 .Case("mktemp", std::make_pair(0,-1))
569 .Case("mkstemp", std::make_pair(0,-1))
570 .Case("mkdtemp", std::make_pair(0,-1))
571 .Case("mkstemps", std::make_pair(0,1))
572 .Default(std::make_pair(-1, -1));
573
574 assert(ArgSuffix.first >= 0 && "Unsupported function")(static_cast <bool> (ArgSuffix.first >= 0 &&
"Unsupported function") ? void (0) : __assert_fail ("ArgSuffix.first >= 0 && \"Unsupported function\""
, "/build/llvm-toolchain-snapshot-7~svn338205/tools/clang/lib/StaticAnalyzer/Checkers/CheckSecuritySyntaxOnly.cpp"
, 574, __extension__ __PRETTY_FUNCTION__))
;
575
576 // Check if the number of arguments is consistent with out expectations.
577 unsigned numArgs = CE->getNumArgs();
578 if ((signed) numArgs <= ArgSuffix.first)
579 return;
580
581 const StringLiteral *strArg =
582 dyn_cast<StringLiteral>(CE->getArg((unsigned)ArgSuffix.first)
583 ->IgnoreParenImpCasts());
584
585 // Currently we only handle string literals. It is possible to do better,
586 // either by looking at references to const variables, or by doing real
587 // flow analysis.
588 if (!strArg || strArg->getCharByteWidth() != 1)
589 return;
590
591 // Count the number of X's, taking into account a possible cutoff suffix.
592 StringRef str = strArg->getString();
593 unsigned numX = 0;
594 unsigned n = str.size();
595
596 // Take into account the suffix.
597 unsigned suffix = 0;
598 if (ArgSuffix.second >= 0) {
599 const Expr *suffixEx = CE->getArg((unsigned)ArgSuffix.second);
600 llvm::APSInt Result;
601 if (!suffixEx->EvaluateAsInt(Result, BR.getContext()))
602 return;
603 // FIXME: Issue a warning.
604 if (Result.isNegative())
605 return;
606 suffix = (unsigned) Result.getZExtValue();
607 n = (n > suffix) ? n - suffix : 0;
608 }
609
610 for (unsigned i = 0; i < n; ++i)
611 if (str[i] == 'X') ++numX;
612
613 if (numX >= 6)
614 return;
615
616 // Issue a warning.
617 PathDiagnosticLocation CELoc =
618 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
619 SmallString<512> buf;
620 llvm::raw_svector_ostream out(buf);
621 out << "Call to '" << Name << "' should have at least 6 'X's in the"
622 " format string to be secure (" << numX << " 'X'";
623 if (numX != 1)
624 out << 's';
625 out << " seen";
626 if (suffix) {
627 out << ", " << suffix << " character";
628 if (suffix > 1)
629 out << 's';
630 out << " used as a suffix";
631 }
632 out << ')';
633 BR.EmitBasicReport(AC->getDecl(), filter.checkName_mkstemp,
634 "Insecure temporary file creation", "Security",
635 out.str(), CELoc, strArg->getSourceRange());
636}
637
638//===----------------------------------------------------------------------===//
639// Check: Any use of 'strcpy' is insecure.
640//
641// CWE-119: Improper Restriction of Operations within
642// the Bounds of a Memory Buffer
643//===----------------------------------------------------------------------===//
644void WalkAST::checkCall_strcpy(const CallExpr *CE, const FunctionDecl *FD) {
645 if (!filter.check_strcpy)
646 return;
647
648 if (!checkCall_strCommon(CE, FD))
649 return;
650
651 const auto *Target = CE->getArg(0)->IgnoreImpCasts(),
652 *Source = CE->getArg(1)->IgnoreImpCasts();
653 if (const auto *DeclRef = dyn_cast<DeclRefExpr>(Target))
654 if (const auto *Array = dyn_cast<ConstantArrayType>(DeclRef->getType())) {
655 uint64_t ArraySize = BR.getContext().getTypeSize(Array) / 8;
656 if (const auto *String = dyn_cast<StringLiteral>(Source)) {
657 if (ArraySize >= String->getLength() + 1)
658 return;
659 }
660 }
661
662 // Issue a warning.
663 PathDiagnosticLocation CELoc =
664 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
665 BR.EmitBasicReport(AC->getDecl(), filter.checkName_strcpy,
666 "Potential insecure memory buffer bounds restriction in "
667 "call 'strcpy'",
668 "Security",
669 "Call to function 'strcpy' is insecure as it does not "
670 "provide bounding of the memory buffer. Replace "
671 "unbounded copy functions with analogous functions that "
672 "support length arguments such as 'strlcpy'. CWE-119.",
673 CELoc, CE->getCallee()->getSourceRange());
674}
675
676//===----------------------------------------------------------------------===//
677// Check: Any use of 'strcat' is insecure.
678//
679// CWE-119: Improper Restriction of Operations within
680// the Bounds of a Memory Buffer
681//===----------------------------------------------------------------------===//
682void WalkAST::checkCall_strcat(const CallExpr *CE, const FunctionDecl *FD) {
683 if (!filter.check_strcpy)
684 return;
685
686 if (!checkCall_strCommon(CE, FD))
687 return;
688
689 // Issue a warning.
690 PathDiagnosticLocation CELoc =
691 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
692 BR.EmitBasicReport(AC->getDecl(), filter.checkName_strcpy,
693 "Potential insecure memory buffer bounds restriction in "
694 "call 'strcat'",
695 "Security",
696 "Call to function 'strcat' is insecure as it does not "
697 "provide bounding of the memory buffer. Replace "
698 "unbounded copy functions with analogous functions that "
699 "support length arguments such as 'strlcat'. CWE-119.",
700 CELoc, CE->getCallee()->getSourceRange());
701}
702
703//===----------------------------------------------------------------------===//
704// Common check for str* functions with no bounds parameters.
705//===----------------------------------------------------------------------===//
706bool WalkAST::checkCall_strCommon(const CallExpr *CE, const FunctionDecl *FD) {
707 const FunctionProtoType *FPT = FD->getType()->getAs<FunctionProtoType>();
708 if (!FPT)
709 return false;
710
711 // Verify the function takes two arguments, three in the _chk version.
712 int numArgs = FPT->getNumParams();
713 if (numArgs != 2 && numArgs != 3)
714 return false;
715
716 // Verify the type for both arguments.
717 for (int i = 0; i < 2; i++) {
718 // Verify that the arguments are pointers.
719 const PointerType *PT = FPT->getParamType(i)->getAs<PointerType>();
720 if (!PT)
721 return false;
722
723 // Verify that the argument is a 'char*'.
724 if (PT->getPointeeType().getUnqualifiedType() != BR.getContext().CharTy)
725 return false;
726 }
727
728 return true;
729}
730
731//===----------------------------------------------------------------------===//
732// Check: Linear congruent random number generators should not be used
733// Originally: <rdar://problem/63371000>
734// CWE-338: Use of cryptographically weak prng
735//===----------------------------------------------------------------------===//
736
737void WalkAST::checkCall_rand(const CallExpr *CE, const FunctionDecl *FD) {
738 if (!filter.check_rand || !CheckRand)
739 return;
740
741 const FunctionProtoType *FTP = FD->getType()->getAs<FunctionProtoType>();
742 if (!FTP)
743 return;
744
745 if (FTP->getNumParams() == 1) {
746 // Is the argument an 'unsigned short *'?
747 // (Actually any integer type is allowed.)
748 const PointerType *PT = FTP->getParamType(0)->getAs<PointerType>();
749 if (!PT)
750 return;
751
752 if (! PT->getPointeeType()->isIntegralOrUnscopedEnumerationType())
753 return;
754 } else if (FTP->getNumParams() != 0)
755 return;
756
757 // Issue a warning.
758 SmallString<256> buf1;
759 llvm::raw_svector_ostream os1(buf1);
760 os1 << '\'' << *FD << "' is a poor random number generator";
761
762 SmallString<256> buf2;
763 llvm::raw_svector_ostream os2(buf2);
764 os2 << "Function '" << *FD
765 << "' is obsolete because it implements a poor random number generator."
766 << " Use 'arc4random' instead";
767
768 PathDiagnosticLocation CELoc =
769 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
770 BR.EmitBasicReport(AC->getDecl(), filter.checkName_rand, os1.str(),
771 "Security", os2.str(), CELoc,
772 CE->getCallee()->getSourceRange());
773}
774
775//===----------------------------------------------------------------------===//
776// Check: 'random' should not be used
777// Originally: <rdar://problem/63371000>
778//===----------------------------------------------------------------------===//
779
780void WalkAST::checkCall_random(const CallExpr *CE, const FunctionDecl *FD) {
781 if (!CheckRand || !filter.check_rand)
782 return;
783
784 const FunctionProtoType *FTP = FD->getType()->getAs<FunctionProtoType>();
785 if (!FTP)
786 return;
787
788 // Verify that the function takes no argument.
789 if (FTP->getNumParams() != 0)
790 return;
791
792 // Issue a warning.
793 PathDiagnosticLocation CELoc =
794 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
795 BR.EmitBasicReport(AC->getDecl(), filter.checkName_rand,
796 "'random' is not a secure random number generator",
797 "Security",
798 "The 'random' function produces a sequence of values that "
799 "an adversary may be able to predict. Use 'arc4random' "
800 "instead", CELoc, CE->getCallee()->getSourceRange());
801}
802
803//===----------------------------------------------------------------------===//
804// Check: 'vfork' should not be used.
805// POS33-C: Do not use vfork().
806//===----------------------------------------------------------------------===//
807
808void WalkAST::checkCall_vfork(const CallExpr *CE, const FunctionDecl *FD) {
809 if (!filter.check_vfork)
810 return;
811
812 // All calls to vfork() are insecure, issue a warning.
813 PathDiagnosticLocation CELoc =
814 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
815 BR.EmitBasicReport(AC->getDecl(), filter.checkName_vfork,
816 "Potential insecure implementation-specific behavior in "
817 "call 'vfork'",
818 "Security",
819 "Call to function 'vfork' is insecure as it can lead to "
820 "denial of service situations in the parent process. "
821 "Replace calls to vfork with calls to the safer "
822 "'posix_spawn' function",
823 CELoc, CE->getCallee()->getSourceRange());
824}
825
826//===----------------------------------------------------------------------===//
827// Check: Should check whether privileges are dropped successfully.
828// Originally: <rdar://problem/6337132>
829//===----------------------------------------------------------------------===//
830
831void WalkAST::checkUncheckedReturnValue(CallExpr *CE) {
832 if (!filter.check_UncheckedReturn)
833 return;
834
835 const FunctionDecl *FD = CE->getDirectCallee();
836 if (!FD)
837 return;
838
839 if (II_setid[0] == nullptr) {
840 static const char * const identifiers[num_setids] = {
841 "setuid", "setgid", "seteuid", "setegid",
842 "setreuid", "setregid"
843 };
844
845 for (size_t i = 0; i < num_setids; i++)
846 II_setid[i] = &BR.getContext().Idents.get(identifiers[i]);
847 }
848
849 const IdentifierInfo *id = FD->getIdentifier();
850 size_t identifierid;
851
852 for (identifierid = 0; identifierid < num_setids; identifierid++)
853 if (id == II_setid[identifierid])
854 break;
855
856 if (identifierid >= num_setids)
857 return;
858
859 const FunctionProtoType *FTP = FD->getType()->getAs<FunctionProtoType>();
860 if (!FTP)
861 return;
862
863 // Verify that the function takes one or two arguments (depending on
864 // the function).
865 if (FTP->getNumParams() != (identifierid < 4 ? 1 : 2))
866 return;
867
868 // The arguments must be integers.
869 for (unsigned i = 0; i < FTP->getNumParams(); i++)
870 if (!FTP->getParamType(i)->isIntegralOrUnscopedEnumerationType())
871 return;
872
873 // Issue a warning.
874 SmallString<256> buf1;
875 llvm::raw_svector_ostream os1(buf1);
876 os1 << "Return value is not checked in call to '" << *FD << '\'';
877
878 SmallString<256> buf2;
879 llvm::raw_svector_ostream os2(buf2);
880 os2 << "The return value from the call to '" << *FD
881 << "' is not checked. If an error occurs in '" << *FD
882 << "', the following code may execute with unexpected privileges";
883
884 PathDiagnosticLocation CELoc =
885 PathDiagnosticLocation::createBegin(CE, BR.getSourceManager(), AC);
886 BR.EmitBasicReport(AC->getDecl(), filter.checkName_UncheckedReturn, os1.str(),
887 "Security", os2.str(), CELoc,
888 CE->getCallee()->getSourceRange());
889}
890
891//===----------------------------------------------------------------------===//
892// SecuritySyntaxChecker
893//===----------------------------------------------------------------------===//
894
895namespace {
896class SecuritySyntaxChecker : public Checker<check::ASTCodeBody> {
897public:
898 ChecksFilter filter;
899
900 void checkASTCodeBody(const Decl *D, AnalysisManager& mgr,
901 BugReporter &BR) const {
902 WalkAST walker(BR, mgr.getAnalysisDeclContext(D), filter);
903 walker.Visit(D->getBody());
904 }
905};
906}
907
908#define REGISTER_CHECKER(name)void ento::registername(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_name = true; checker->filter.checkName_name
= mgr.getCurrentCheckName(); }
\
909 void ento::register##name(CheckerManager &mgr) { \
910 SecuritySyntaxChecker *checker = \
911 mgr.registerChecker<SecuritySyntaxChecker>(); \
912 checker->filter.check_##name = true; \
913 checker->filter.checkName_##name = mgr.getCurrentCheckName(); \
914 }
915
916REGISTER_CHECKER(bcmp)void ento::registerbcmp(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_bcmp = true; checker->filter.checkName_bcmp
= mgr.getCurrentCheckName(); }
917REGISTER_CHECKER(bcopy)void ento::registerbcopy(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_bcopy = true; checker->filter.
checkName_bcopy = mgr.getCurrentCheckName(); }
918REGISTER_CHECKER(bzero)void ento::registerbzero(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_bzero = true; checker->filter.
checkName_bzero = mgr.getCurrentCheckName(); }
919REGISTER_CHECKER(gets)void ento::registergets(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_gets = true; checker->filter.checkName_gets
= mgr.getCurrentCheckName(); }
920REGISTER_CHECKER(getpw)void ento::registergetpw(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_getpw = true; checker->filter.
checkName_getpw = mgr.getCurrentCheckName(); }
921REGISTER_CHECKER(mkstemp)void ento::registermkstemp(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_mkstemp = true; checker->filter
.checkName_mkstemp = mgr.getCurrentCheckName(); }
922REGISTER_CHECKER(mktemp)void ento::registermktemp(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_mktemp = true; checker->filter
.checkName_mktemp = mgr.getCurrentCheckName(); }
923REGISTER_CHECKER(strcpy)void ento::registerstrcpy(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_strcpy = true; checker->filter
.checkName_strcpy = mgr.getCurrentCheckName(); }
924REGISTER_CHECKER(rand)void ento::registerrand(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_rand = true; checker->filter.checkName_rand
= mgr.getCurrentCheckName(); }
925REGISTER_CHECKER(vfork)void ento::registervfork(CheckerManager &mgr) { SecuritySyntaxChecker
*checker = mgr.registerChecker<SecuritySyntaxChecker>(
); checker->filter.check_vfork = true; checker->filter.
checkName_vfork = mgr.getCurrentCheckName(); }
926REGISTER_CHECKER(FloatLoopCounter)void ento::registerFloatLoopCounter(CheckerManager &mgr) {
SecuritySyntaxChecker *checker = mgr.registerChecker<SecuritySyntaxChecker
>(); checker->filter.check_FloatLoopCounter = true; checker
->filter.checkName_FloatLoopCounter = mgr.getCurrentCheckName
(); }
927REGISTER_CHECKER(UncheckedReturn)void ento::registerUncheckedReturn(CheckerManager &mgr) {
SecuritySyntaxChecker *checker = mgr.registerChecker<SecuritySyntaxChecker
>(); checker->filter.check_UncheckedReturn = true; checker
->filter.checkName_UncheckedReturn = mgr.getCurrentCheckName
(); }
928
929