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[clang][analyzer] Improve bug report in alpha.security.ReturnPtrRange 

Add some notes and track of bad return value.

Reviewed By: steakhal

Differential Revision: https://reviews.llvm.org/D107051
This commit is contained in:
Balázs Kéri 2021-08-11 11:19:19 +02:00
parent f6748b24d4
commit 9f517fd11e
3 changed files with 105 additions and 29 deletions
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43
clang/lib/StaticAnalyzer/Checkers/ReturnPointerRangeChecker.cpp
View File

@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporterVisitors.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
@ -79,16 +80,44 @@ void ReturnPointerRangeChecker::checkPreStmt(const ReturnStmt *RS,
"Returned pointer value points outside the original object "
"(potential buffer overflow)"));
// FIXME: It would be nice to eventually make this diagnostic more clear,
// e.g., by referencing the original declaration or by saying *why* this
// reference is outside the range.
// Generate a report for this bug.
auto report =
auto Report =
std::make_unique<PathSensitiveBugReport>(*BT, BT->getDescription(), N);
Report->addRange(RetE->getSourceRange());
report->addRange(RetE->getSourceRange());
C.emitReport(std::move(report));
const auto ConcreteElementCount = ElementCount.getAs<nonloc::ConcreteInt>();
const auto ConcreteIdx = Idx.getAs<nonloc::ConcreteInt>();
const auto *DeclR = ER->getSuperRegion()->getAs<DeclRegion>();
if (DeclR)
Report->addNote("Original object declared here",
{DeclR->getDecl(), C.getSourceManager()});
if (ConcreteElementCount) {
SmallString<128> SBuf;
llvm::raw_svector_ostream OS(SBuf);
OS << "Original object ";
if (DeclR) {
OS << "'";
DeclR->getDecl()->printName(OS);
OS << "' ";
}
OS << "is an array of " << ConcreteElementCount->getValue() << " '";
ER->getValueType().print(OS,
PrintingPolicy(C.getASTContext().getLangOpts()));
OS << "' objects";
if (ConcreteIdx) {
OS << ", returned pointer points at index " << ConcreteIdx->getValue();
}
Report->addNote(SBuf,
{RetE, C.getSourceManager(), C.getLocationContext()});
}
bugreporter::trackExpressionValue(N, RetE, *Report);
C.emitReport(std::move(Report));
}
}

3
clang/test/Analysis/misc-ps-region-store.m
View File

@ -461,10 +461,11 @@ void element_region_with_symbolic_superregion(int* p) {
// Test returning an out-of-bounds pointer (CWE-466)
//===----------------------------------------------------------------------===//
static int test_cwe466_return_outofbounds_pointer_a[10];
static int test_cwe466_return_outofbounds_pointer_a[10]; // expected-note{{Original object declared here}}
int *test_cwe466_return_outofbounds_pointer() {
int *p = test_cwe466_return_outofbounds_pointer_a+11;
return p; // expected-warning{{Returned pointer value points outside the original object}}
// expected-note@-1{{Original object 'test_cwe466_return_outofbounds_pointer_a' is an array of 10 'int' objects, returned pointer points at index 11}}
}
//===----------------------------------------------------------------------===//

88
clang/test/Analysis/return-ptr-range.cpp
View File

@ -1,29 +1,39 @@
// RUN: %clang_analyze_cc1 -analyzer-checker=alpha.security.ReturnPtrRange -verify %s
int arr[10];
int *ptr;
// RUN: %clang_analyze_cc1 -analyzer-checker=core,alpha.security.ReturnPtrRange -analyzer-output text -verify %s
int conjure_index();
int *test_element_index_lifetime() {
do {
namespace test_element_index_lifetime {
int arr[10]; // expected-note{{Original object declared here}} expected-note{{Original object declared here}}
int *ptr;
int *test_global_ptr() {
do { // expected-note{{Loop condition is false. Exiting loop}}
int x = conjure_index();
ptr = arr + x;
if (x != 20)
ptr = arr + x; // expected-note{{Value assigned to 'ptr'}}
if (x != 20) // expected-note{{Assuming 'x' is equal to 20}}
// expected-note@-1{{Taking false branch}}
return arr; // no-warning
} while (0);
return ptr; // expected-warning{{Returned pointer value points outside the original object (potential buffer overflow)}}
} while(0);
return ptr; // expected-warning{{Returned pointer value points outside the original object (potential buffer overflow) [alpha.security.ReturnPtrRange]}}
// expected-note@-1{{Returned pointer value points outside the original object (potential buffer overflow)}}
// expected-note@-2{{Original object 'arr' is an array of 10 'int' objects}}
}
int *test_element_index_lifetime_with_local_ptr() {
int *test_local_ptr() {
int *local_ptr;
do {
do { // expected-note{{Loop condition is false. Exiting loop}}
int x = conjure_index();
local_ptr = arr + x;
if (x != 20)
local_ptr = arr + x; // expected-note{{Value assigned to 'local_ptr'}}
if (x != 20) // expected-note{{Assuming 'x' is equal to 20}}
// expected-note@-1{{Taking false branch}}
return arr; // no-warning
} while (0);
return local_ptr; // expected-warning{{Returned pointer value points outside the original object (potential buffer overflow)}}
} while(0);
return local_ptr; // expected-warning{{Returned pointer value points outside the original object (potential buffer overflow) [alpha.security.ReturnPtrRange]}}
// expected-note@-1{{Returned pointer value points outside the original object (potential buffer overflow)}}
// expected-note@-2{{Original object 'arr' is an array of 10 'int' objects}}
}
}
template <typename T, int N>
@ -55,17 +65,53 @@ void use_iterable_object() {
template <int N>
class BadIterable {
int buffer[N];
int buffer[N]; // expected-note{{Original object declared here}}
int *start, *finish;
public:
BadIterable() : start(buffer), finish(buffer + N) {}
BadIterable() : start(buffer), finish(buffer + N) {} // expected-note{{Value assigned to 'iter.finish'}}
int* begin() { return start; }
int* end() { return finish + 1; } // expected-warning{{Returned pointer value points outside the original object (potential buffer overflow)}}
int* end() { return finish + 1; } // expected-warning{{Returned pointer value points outside the original object}}
// expected-note@-1{{Returned pointer value points outside the original object}}
// expected-note@-2{{Original object 'buffer' is an array of 20 'int' objects, returned pointer points at index 21}}
};
void use_bad_iterable_object() {
BadIterable<20> iter;
iter.end();
BadIterable<20> iter; // expected-note{{Calling default constructor for 'BadIterable<20>'}}
// expected-note@-1{{Returning from default constructor for 'BadIterable<20>'}}
iter.end(); // expected-note{{Calling 'BadIterable::end'}}
}
int *test_idx_sym(int I) {
static int arr[10]; // expected-note{{Original object declared here}} expected-note{{'arr' initialized here}}
if (I != 11) // expected-note{{Assuming 'I' is equal to 11}}
// expected-note@-1{{Taking false branch}}
return arr;
return arr + I; // expected-warning{{Returned pointer value points outside the original object}}
// expected-note@-1{{Returned pointer value points outside the original object}}
// expected-note@-2{{Original object 'arr' is an array of 10 'int' objects, returned pointer points at index 11}}
}
namespace test_array_of_struct {
struct Data {
int A;
char *B;
};
Data DataArr[10]; // expected-note{{Original object declared here}}
Data *test_struct_array() {
int I = conjure_index();
if (I != 11) // expected-note{{Assuming 'I' is equal to 11}}
// expected-note@-1{{Taking false branch}}
return DataArr;
return DataArr + I; // expected-warning{{Returned pointer value points outside the original object}}
// expected-note@-1{{Returned pointer value points outside the original object}}
// expected-note@-2{{Original object 'DataArr' is an array of 10 'test_array_of_struct::Data' objects, returned pointer points at index 11}}
}
}