[llvm-branch-commits] [clang] 4d5dad4 - [analyzer] Fix null pointer deref in CastValueChecker
Tom Stellard via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Thu Jun 9 14:00:08 PDT 2022
Author: Vince Bridgers
Date: 2022-06-09T13:59:40-07:00
New Revision: 4d5dad43b2ebd81247ba1355383301495a7398c9
URL: https://github.com/llvm/llvm-project/commit/4d5dad43b2ebd81247ba1355383301495a7398c9
DIFF: https://github.com/llvm/llvm-project/commit/4d5dad43b2ebd81247ba1355383301495a7398c9.diff
LOG: [analyzer] Fix null pointer deref in CastValueChecker
A crash was seen in CastValueChecker due to a null pointer dereference.
The fix uses QualType::getAsString to avoid the null dereference
when a CXXRecordDecl cannot be obtained. A small reproducer is added,
and cast value notes LITs are updated for the new debug messages.
Reviewed By: steakhal
Differential Revision: https://reviews.llvm.org/D127105
(cherry picked from commit c7fa4e8a8bc41e52cc49a27e0495d67d730fa167)
Added:
Modified:
clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp
clang/test/Analysis/cast-value-notes.cpp
clang/test/Analysis/cast-value-state-dump.cpp
Removed:
################################################################################
diff --git a/clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp
index 4235c0c138210..945590d0ba8c7 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CastValueChecker.cpp
@@ -108,7 +108,7 @@ static const NoteTag *getNoteTag(CheckerContext &C,
bool CastSucceeds, bool IsKnownCast) {
std::string CastToName =
CastInfo ? CastInfo->to()->getAsCXXRecordDecl()->getNameAsString()
- : CastToTy->getPointeeCXXRecordDecl()->getNameAsString();
+ : CastToTy.getAsString();
Object = Object->IgnoreParenImpCasts();
return C.getNoteTag(
@@ -163,9 +163,9 @@ static const NoteTag *getNoteTag(CheckerContext &C,
bool First = true;
for (QualType CastToTy: CastToTyVec) {
std::string CastToName =
- CastToTy->getAsCXXRecordDecl() ?
- CastToTy->getAsCXXRecordDecl()->getNameAsString() :
- CastToTy->getPointeeCXXRecordDecl()->getNameAsString();
+ CastToTy->getAsCXXRecordDecl()
+ ? CastToTy->getAsCXXRecordDecl()->getNameAsString()
+ : CastToTy.getAsString();
Out << ' ' << ((CastToTyVec.size() == 1) ? "not" :
(First ? "neither" : "nor")) << " a '" << CastToName
<< '\'';
diff --git a/clang/test/Analysis/cast-value-notes.cpp b/clang/test/Analysis/cast-value-notes.cpp
index a09586309fb41..2506fd9021ab4 100644
--- a/clang/test/Analysis/cast-value-notes.cpp
+++ b/clang/test/Analysis/cast-value-notes.cpp
@@ -23,7 +23,7 @@ using namespace clang;
void evalReferences(const Shape &S) {
const auto &C = dyn_cast<Circle>(S);
- // expected-note at -1 {{Assuming 'S' is not a 'Circle'}}
+ // expected-note at -1 {{Assuming 'S' is not a 'const class clang::Circle &'}}
// expected-note at -2 {{Dereference of null pointer}}
// expected-warning at -3 {{Dereference of null pointer}}
}
@@ -33,25 +33,25 @@ void evalNonNullParamNonNullReturnReference(const Shape &S) {
// expected-note at -1 {{'C' initialized here}}
if (!dyn_cast_or_null<Circle>(C)) {
- // expected-note at -1 {{'C' is a 'Circle'}}
+ // expected-note at -1 {{Assuming 'C' is a 'const class clang::Circle *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
if (dyn_cast_or_null<Triangle>(C)) {
- // expected-note at -1 {{Assuming 'C' is not a 'Triangle'}}
+ // expected-note at -1 {{Assuming 'C' is not a 'const class clang::Triangle *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
if (dyn_cast_or_null<Rectangle>(C)) {
- // expected-note at -1 {{Assuming 'C' is not a 'Rectangle'}}
+ // expected-note at -1 {{Assuming 'C' is not a 'const class clang::Rectangle *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
if (dyn_cast_or_null<Hexagon>(C)) {
- // expected-note at -1 {{Assuming 'C' is not a 'Hexagon'}}
+ // expected-note at -1 {{Assuming 'C' is not a 'const class clang::Hexagon *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
@@ -87,29 +87,29 @@ void evalNonNullParamNonNullReturnReference(const Shape &S) {
void evalNonNullParamNonNullReturn(const Shape *S) {
const auto *C = cast<Circle>(S);
- // expected-note at -1 {{'S' is a 'Circle'}}
+ // expected-note at -1 {{'S' is a 'const class clang::Circle *'}}
// expected-note at -2 {{'C' initialized here}}
if (!dyn_cast_or_null<Circle>(C)) {
- // expected-note at -1 {{'C' is a 'Circle'}}
+ // expected-note at -1 {{Assuming 'C' is a 'const class clang::Circle *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
if (dyn_cast_or_null<Triangle>(C)) {
- // expected-note at -1 {{Assuming 'C' is not a 'Triangle'}}
+ // expected-note at -1 {{Assuming 'C' is not a 'const class clang::Triangle *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
if (dyn_cast_or_null<Rectangle>(C)) {
- // expected-note at -1 {{Assuming 'C' is not a 'Rectangle'}}
+ // expected-note at -1 {{Assuming 'C' is not a 'const class clang::Rectangle *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
if (dyn_cast_or_null<Hexagon>(C)) {
- // expected-note at -1 {{Assuming 'C' is not a 'Hexagon'}}
+ // expected-note at -1 {{Assuming 'C' is not a 'const class clang::Hexagon *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
@@ -145,10 +145,10 @@ void evalNonNullParamNonNullReturn(const Shape *S) {
void evalNonNullParamNullReturn(const Shape *S) {
const auto *C = dyn_cast_or_null<Circle>(S);
- // expected-note at -1 {{Assuming 'S' is not a 'Circle'}}
+ // expected-note at -1 {{Assuming 'S' is not a 'const class clang::Circle *'}}
if (const auto *T = dyn_cast_or_null<Triangle>(S)) {
- // expected-note at -1 {{Assuming 'S' is a 'Triangle'}}
+ // expected-note at -1 {{Assuming 'S' is a 'const class clang::Triangle *'}}
// expected-note at -2 {{'T' initialized here}}
// expected-note at -3 {{'T' is non-null}}
// expected-note at -4 {{Taking true branch}}
@@ -172,7 +172,7 @@ void evalNullParamNullReturn(const Shape *S) {
void evalZeroParamNonNullReturnPointer(const Shape *S) {
const auto *C = S->castAs<Circle>();
- // expected-note at -1 {{'S' is a 'Circle'}}
+ // expected-note at -1 {{'S' is a 'const class clang::Circle *'}}
// expected-note at -2 {{'C' initialized here}}
(void)(1 / !C);
@@ -193,12 +193,12 @@ void evalZeroParamNonNullReturn(const Shape &S) {
void evalZeroParamNullReturn(const Shape *S) {
const auto &C = S->getAs<Circle>();
- // expected-note at -1 {{Assuming 'S' is not a 'Circle'}}
+ // expected-note at -1 {{Assuming 'S' is not a 'const class clang::Circle *'}}
// expected-note at -2 {{Storing null pointer value}}
// expected-note at -3 {{'C' initialized here}}
if (!dyn_cast_or_null<Triangle>(S)) {
- // expected-note at -1 {{Assuming 'S' is a 'Triangle'}}
+ // expected-note at -1 {{Assuming 'S' is a 'const class clang::Triangle *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
@@ -213,3 +213,32 @@ void evalZeroParamNullReturn(const Shape *S) {
// expected-note at -1 {{Division by zero}}
// expected-warning at -2 {{Division by zero}}
}
+
+// don't crash
+// CastValueChecker was using QualType()->getPointeeCXXRecordDecl(), in
+// getNoteTag which evaluated to nullptr, then crashed when attempting to
+// deref an invocation to getNameAsString(). The fix is to use
+// QualType().getAsString().
+//
+// Example:
+// std::string CastToName =
+// CastInfo ? CastInfo->to()->getAsCXXRecordDecl()->getNameAsString()
+// : CastToTy->getPointeeCXXRecordDecl()->getNameAsString();
+// Changed to:
+// std::string CastToName =
+// CastInfo ? CastInfo->to()->getAsCXXRecordDecl()->getNameAsString()
+// : CastToTy.getAsString();
+namespace llvm {
+template <typename, typename a> void isa(a &);
+template <typename> class PointerUnion {
+public:
+ template <typename T> T *getAs() {
+ (void)isa<int>(*this);
+ return nullptr;
+ }
+};
+class LLVMContext {
+ PointerUnion<LLVMContext> c;
+ void d() { c.getAs<int>(); }
+};
+} // namespace llvm
diff --git a/clang/test/Analysis/cast-value-state-dump.cpp b/clang/test/Analysis/cast-value-state-dump.cpp
index 3e6a40cf1319b..c9d85f0b4460f 100644
--- a/clang/test/Analysis/cast-value-state-dump.cpp
+++ b/clang/test/Analysis/cast-value-state-dump.cpp
@@ -18,12 +18,12 @@ using namespace clang;
void evalNonNullParamNonNullReturn(const Shape *S) {
const auto *C = dyn_cast_or_null<Circle>(S);
- // expected-note at -1 {{Assuming 'S' is a 'Circle'}}
+ // expected-note at -1 {{Assuming 'S' is a 'const class clang::Circle *'}}
// expected-note at -2 {{'C' initialized here}}
// FIXME: We assumed that 'S' is a 'Circle' therefore it is not a 'Square'.
if (dyn_cast_or_null<Square>(S)) {
- // expected-note at -1 {{Assuming 'S' is not a 'Square'}}
+ // expected-note at -1 {{Assuming 'S' is not a 'const class clang::Square *'}}
// expected-note at -2 {{Taking false branch}}
return;
}
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