3 files changed, 16 insertions, 2 deletions
diff --git a/src/corelib/kernel/qcore_unix_p.h b/src/corelib/kernel/qcore_unix_p.h
index c744873fce..f80dcb5a50 100644
--- a/src/corelib/kernel/qcore_unix_p.h
+++ b/src/corelib/kernel/qcore_unix_p.h
@@ -47,6 +47,7 @@
 
 #include "qplatformdefs.h"
 #include "qatomic.h"
+#include "qhash.h"
 
 #ifndef Q_OS_UNIX
 # error "qcore_unix_p.h included on a non-Unix system"
@@ -322,6 +323,19 @@ union qt_semun {
     unsigned short *array;      /* array for GETALL, SETALL */
 };
 
+#ifndef QT_POSIX_IPC
+#ifndef QT_NO_SHAREDMEMORY
+#ifndef Q_OS_ANDROID
+static inline key_t qt_safe_ftok(const QByteArray &filename, int proj_id)
+{
+    // Unfortunately ftok can return colliding keys even for different files.
+    // Try to add some more entropy via qHash.
+    return ::ftok(filename.constData(), qHash(filename, proj_id));
+}
+#endif // !Q_OS_ANDROID
+#endif // !QT_NO_SHAREDMEMORY
+#endif // !QT_POSIX_IPC
+
 QT_END_NAMESPACE
 
 #endif
diff --git a/src/corelib/kernel/qsharedmemory_systemv.cpp b/src/corelib/kernel/qsharedmemory_systemv.cpp
index 29fee12c0b..0d2eea49e9 100644
--- a/src/corelib/kernel/qsharedmemory_systemv.cpp
+++ b/src/corelib/kernel/qsharedmemory_systemv.cpp
@@ -82,7 +82,7 @@ key_t QSharedMemoryPrivate::handle()
         return 0;
     }
 
-    unix_key = ftok(QFile::encodeName(nativeKey).constData(), 'Q');
+    unix_key = qt_safe_ftok(QFile::encodeName(nativeKey), 'Q');
     if (-1 == unix_key) {
         errorString = QSharedMemory::tr("%1: ftok failed").arg(QLatin1String("QSharedMemory::handle:"));
         error = QSharedMemory::KeyError;
diff --git a/src/corelib/kernel/qsystemsemaphore_systemv.cpp b/src/corelib/kernel/qsystemsemaphore_systemv.cpp
index 32a4bdef51..490de5f9ee 100644
--- a/src/corelib/kernel/qsystemsemaphore_systemv.cpp
+++ b/src/corelib/kernel/qsystemsemaphore_systemv.cpp
@@ -85,7 +85,7 @@ key_t QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode)
     createdFile = (1 == built);
 
     // Get the unix key for the created file
-    unix_key = ftok(QFile::encodeName(fileName).constData(), 'Q');
+    unix_key = qt_safe_ftok(QFile::encodeName(fileName), 'Q');
     if (-1 == unix_key) {
         errorString = QCoreApplication::tr("%1: ftok failed", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle:"));
         error = QSystemSemaphore::KeyError;