From: Artem Dergachev <artem.dergachev@gmail.com>
Date: Thu, 28 Jun 2018 00:42:11 +0000 (+0000)
Subject: [analyzer] Use sufficiently large types for index bounds calculation.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e79c5536b0d933df63de745592b7228379841d24;p=clang

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

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


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@335803 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/StaticAnalyzer/Core/ProgramState.cpp b/lib/StaticAnalyzer/Core/ProgramState.cpp
index 141863d2ac..2b40160729 100644
--- a/lib/StaticAnalyzer/Core/ProgramState.cpp
+++ b/lib/StaticAnalyzer/Core/ProgramState.cpp
@@ -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.
diff --git a/lib/StaticAnalyzer/Core/RegionStore.cpp b/lib/StaticAnalyzer/Core/RegionStore.cpp
index acb6eeab8d..db6449e6d5 100644
--- a/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -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());
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/test/Analysis/index-type.c b/test/Analysis/index-type.c
index b86913b996..123dcd65bd 100644
--- a/test/Analysis/index-type.c
+++ b/test/Analysis/index-type.c
@@ -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