From 5283a6c87beac5a43f612786fefd6e43f2c70bf6 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Mon, 19 May 2014 16:53:34 -0700
Subject: [PATCH] Disable hash seeding for bootstrapped tools

Any bootstrapped tool is a development tool, by definition. So the
effects of seeding the hash with a random number can cause the same
source input to produce different binary results, which can throw some
caching tools into disarray (like the Open Build System).

There should be minimal fall out from the reduced protection against
DoS. Since those are only development tools, "specially crafted" input
implies the developer is DoS'ing him/herself.

Note: the change to qhash.cpp applies to moc and rcc, which are always
bootstrapped.

Change-Id: I061ab52036e40627c0703f1bf881455cbf848f43
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>
---
 src/corelib/tools/qhash.cpp | 8 ++++----
 src/tools/qdoc/main.cpp     | 2 ++
 src/tools/uic/main.cpp      | 3 +++
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp
index ca645636e44..7200ea7993b 100644
--- a/src/corelib/tools/qhash.cpp
+++ b/src/corelib/tools/qhash.cpp
@@ -222,12 +222,13 @@ uint qHash(QLatin1String key, uint seed) Q_DECL_NOTHROW
 */
 static uint qt_create_qhash_seed()
 {
+    uint seed = 0;
+
+#ifndef QT_BOOTSTRAPPED
     QByteArray envSeed = qgetenv("QT_HASH_SEED");
     if (!envSeed.isNull())
         return envSeed.toUInt();
 
-    uint seed = 0;
-
 #ifdef Q_OS_UNIX
     int randomfd = qt_safe_open("/dev/urandom", O_RDONLY);
     if (randomfd == -1)
@@ -254,17 +255,16 @@ static uint qt_create_qhash_seed()
     seed ^= timestamp;
     seed ^= (timestamp >> 32);
 
-#ifndef QT_BOOTSTRAPPED
     quint64 pid = QCoreApplication::applicationPid();
     seed ^= pid;
     seed ^= (pid >> 32);
-#endif // QT_BOOTSTRAPPED
 
     quintptr seedPtr = reinterpret_cast<quintptr>(&seed);
     seed ^= seedPtr;
 #if QT_POINTER_SIZE == 8
     seed ^= (seedPtr >> 32);
 #endif
+#endif // QT_BOOTSTRAPPED
 
     return seed;
 }
diff --git a/src/tools/qdoc/main.cpp b/src/tools/qdoc/main.cpp
index 398d1884640..3d2ee409b07 100644
--- a/src/tools/qdoc/main.cpp
+++ b/src/tools/qdoc/main.cpp
@@ -542,6 +542,7 @@ static void processQdocconfFile(const QString &fileName)
     Generator::debugSegfault("qdoc finished!");
 }
 
+extern Q_CORE_EXPORT QBasicAtomicInt qt_qhash_seed;
 QT_END_NAMESPACE
 
 int main(int argc, char **argv)
@@ -549,6 +550,7 @@ int main(int argc, char **argv)
     QT_USE_NAMESPACE
 
 #ifndef QT_BOOTSTRAPPED
+    qt_qhash_seed.testAndSetRelaxed(-1, 0); // set the hash seed to 0 if it wasn't set yet
     QCoreApplication app(argc, argv);
 #endif
 
diff --git a/src/tools/uic/main.cpp b/src/tools/uic/main.cpp
index cb2bd430ff4..12b0ee67378 100644
--- a/src/tools/uic/main.cpp
+++ b/src/tools/uic/main.cpp
@@ -52,9 +52,12 @@
 #include <qcommandlineparser.h>
 
 QT_BEGIN_NAMESPACE
+extern Q_CORE_EXPORT QBasicAtomicInt qt_qhash_seed;
 
 int runUic(int argc, char *argv[])
 {
+    qt_qhash_seed.testAndSetRelaxed(-1, 0); // set the hash seed to 0 if it wasn't set yet
+
     QCoreApplication app(argc, argv);
     QCoreApplication::setApplicationVersion(QString::fromLatin1(QT_VERSION_STR));