From d82d5b1c43b270ef6f4f0d90ce5d7d96ea0b7a97 Mon Sep 17 00:00:00 2001
From: Mikhail Lappo <mikhail.lappo@lge.com>
Date: Wed, 3 Jun 2015 10:09:42 +0300
Subject: Check for integer overflows in places where qAllocMore is used

Task-number: QTBUG-41230
Change-Id: Ic2167364e326092482657f2d2b4ab6ad3e5af631
(partially cherry-picked from 880986be2357a1f80827d038d770dc2f80300201)
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/tools/qarraydata.cpp | 16 ++++++++++++++--
 src/corelib/tools/qbytearray.cpp |  7 +++++--
 src/corelib/tools/qlist.cpp      |  2 ++
 src/corelib/tools/qstring.cpp    |  5 ++++-
 src/corelib/tools/qtools_p.h     |  6 ++++++
 5 files changed, 31 insertions(+), 5 deletions(-)

(limited to 'src/corelib')

diff --git a/src/corelib/tools/qarraydata.cpp b/src/corelib/tools/qarraydata.cpp
index 98c484c1dd..d060ff84f2 100644
--- a/src/corelib/tools/qarraydata.cpp
+++ b/src/corelib/tools/qarraydata.cpp
@@ -85,8 +85,20 @@ QArrayData *QArrayData::allocate(size_t objectSize, size_t alignment,
         headerSize += (alignment - Q_ALIGNOF(QArrayData));
 
     // Allocate additional space if array is growing
-    if (options & Grow)
-        capacity = qAllocMore(int(objectSize * capacity), int(headerSize)) / int(objectSize);
+    if (options & Grow) {
+
+        // Guard against integer overflow when multiplying.
+        if (capacity > std::numeric_limits<size_t>::max() / objectSize)
+            return 0;
+
+        size_t alloc = objectSize * capacity;
+
+        // Make sure qAllocMore won't overflow.
+        if (headerSize > size_t(MaxAllocSize) || alloc > size_t(MaxAllocSize) - headerSize)
+            return 0;
+
+        capacity = qAllocMore(int(alloc), int(headerSize)) / int(objectSize);
+    }
 
     size_t allocSize = headerSize + objectSize * capacity;
 
diff --git a/src/corelib/tools/qbytearray.cpp b/src/corelib/tools/qbytearray.cpp
index 5ec8c317e8..1e87f7b023 100644
--- a/src/corelib/tools/qbytearray.cpp
+++ b/src/corelib/tools/qbytearray.cpp
@@ -64,7 +64,7 @@ int qFindByteArray(
 int qAllocMore(int alloc, int extra) Q_DECL_NOTHROW
 {
     Q_ASSERT(alloc >= 0 && extra >= 0);
-    Q_ASSERT_X(uint(alloc) < QByteArray::MaxSize, "qAllocMore", "Requested size is too large!");
+    Q_ASSERT_X(alloc <= MaxAllocSize - extra, "qAllocMore", "Requested size is too large!");
 
     unsigned nalloc = qNextPowerOfTwo(alloc + extra);
 
@@ -1495,8 +1495,11 @@ void QByteArray::reallocData(uint alloc, Data::AllocationOptions options)
             Data::deallocate(d);
         d = x;
     } else {
-        if (options & Data::Grow)
+        if (options & Data::Grow) {
+            if (alloc > uint(MaxAllocSize) - uint(sizeof(Data)))
+                qBadAlloc();
             alloc = qAllocMore(alloc, sizeof(Data));
+        }
         Data *x = static_cast<Data *>(::realloc(d, sizeof(Data) + alloc));
         Q_CHECK_PTR(x);
         x->alloc = alloc;
diff --git a/src/corelib/tools/qlist.cpp b/src/corelib/tools/qlist.cpp
index fe5e0f33b4..b91fd38a5f 100644
--- a/src/corelib/tools/qlist.cpp
+++ b/src/corelib/tools/qlist.cpp
@@ -55,6 +55,8 @@ const QListData::Data QListData::shared_null = { Q_REFCOUNT_INITIALIZE_STATIC, 0
 
 static int grow(int size)
 {
+    if (size_t(size) > (MaxAllocSize - QListData::DataHeaderSize) / sizeof(void *))
+        qBadAlloc();
     // dear compiler: don't optimize me out.
     volatile int x = qAllocMore(size * sizeof(void *), QListData::DataHeaderSize) / sizeof(void *);
     return x;
diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index 189caf8bd7..96f3c4147c 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -1656,8 +1656,11 @@ void QString::resize(int size)
 
 void QString::reallocData(uint alloc, bool grow)
 {
-    if (grow)
+    if (grow) {
+        if (alloc > (uint(MaxAllocSize) - sizeof(Data)) / sizeof(QChar))
+            qBadAlloc();
         alloc = qAllocMore(alloc * sizeof(QChar), sizeof(Data)) / sizeof(QChar);
+    }
 
     if (d->ref.isShared() || IS_RAW_DATA(d)) {
         Data::AllocationOptions allocOptions(d->capacityReserved ? Data::CapacityReserved : 0);
diff --git a/src/corelib/tools/qtools_p.h b/src/corelib/tools/qtools_p.h
index 3876d3822c..1e72db1d87 100644
--- a/src/corelib/tools/qtools_p.h
+++ b/src/corelib/tools/qtools_p.h
@@ -46,9 +46,15 @@
 //
 
 #include "QtCore/qglobal.h"
+#include <limits>
 
 QT_BEGIN_NAMESPACE
 
+// We typically need an extra bit for qNextPowerOfTwo when determining the next allocation size.
+enum {
+    MaxAllocSize = (1 << (std::numeric_limits<int>::digits - 1)) - 1
+};
+
 // implemented in qbytearray.cpp
 int Q_CORE_EXPORT qAllocMore(int alloc, int extra) Q_DECL_NOTHROW;
 
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