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[analyzer] Use sufficiently large types for index bounds calculation.

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The ProgramState::assumeInBound() API is used by checkers to make an assumption
that a certain array index is within the array's bounds (i.e. is greater than or
equal to 0 and is less than the length of the array). When the type of the
index was unspecified by the caller, it assumed that the type is 'int', which
caused some indices and sizes to truncate during calculations.

Use ArrayIndexTy by default instead, which is used by the analyzer to represent
index types and is currently hardcoded to long long.

Patch by Bevin Hansson!

Differential Revision: https://reviews.llvm.org/D46944

llvm-svn: 335803
This commit is contained in:
Artem Dergachev 2018-06-28 00:42:11 +00:00
parent 348dd9ddd1
commit 0bb974e3ee
3 changed files with 24 additions and 5 deletions
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3
clang/lib/StaticAnalyzer/Core/ProgramState.cpp
View File

@ -336,9 +336,8 @@ ProgramStateRef ProgramState::assumeInBound(DefinedOrUnknownSVal Idx,
// Get the offset: the minimum value of the array index type.
BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
// FIXME: This should be using ValueManager::ArrayindexTy...somehow.
if (indexTy.isNull())
indexTy = Ctx.IntTy;
indexTy = svalBuilder.getArrayIndexType();
nonloc::ConcreteInt Min(BVF.getMinValue(indexTy));
// Adjust the index.

3
clang/lib/StaticAnalyzer/Core/RegionStore.cpp
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@ -1341,7 +1341,8 @@ RegionStoreManager::getSizeInElements(ProgramStateRef state,
// If a variable is reinterpreted as a type that doesn't fit into a larger
// type evenly, round it down.
// This is a signed value, since it's used in arithmetic with signed indices.
return svalBuilder.makeIntVal(RegionSize / EleSize, false);
return svalBuilder.makeIntVal(RegionSize / EleSize,
svalBuilder.getArrayIndexType());
}
//===----------------------------------------------------------------------===//

23
clang/test/Analysis/index-type.c
View File

@ -1,5 +1,5 @@
// RUN: %clang_analyze_cc1 -triple x86_64-apple-darwin10 -analyzer-checker=core,alpha.security.ArrayBoundV2 -verify %s
// RUN: %clang_analyze_cc1 -triple i386-apple-darwin10 -analyzer-checker=core,alpha.security.ArrayBoundV2 -DM32 -verify %s
// RUN: %clang_analyze_cc1 -triple x86_64-apple-darwin10 -analyzer-checker=core,alpha.security.ArrayBoundV2 -Wno-implicit-function-declaration -verify %s
// RUN: %clang_analyze_cc1 -triple i386-apple-darwin10 -analyzer-checker=core,alpha.security.ArrayBoundV2 -Wno-implicit-function-declaration -DM32 -verify %s
// expected-no-diagnostics
#define UINT_MAX (~0u)
@ -36,4 +36,23 @@ void testIndexTooBig64() {
*ptr = 42; // no-warning
}
#define SIZE 4294967296
static unsigned size;
static void * addr;
static unsigned buf[SIZE];
void testOutOfBounds() {
// Not out of bounds.
buf[SIZE-1] = 1; // no-warning
}
void testOutOfBoundsCopy1() {
memcpy(buf, addr, size); // no-warning
}
void testOutOfBoundsCopy2() {
memcpy(addr, buf, size); // no-warning
}
#endif