diff options
| -rw-r--r-- | src/corelib/io/qfsfileengine_unix.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/corelib/io/qfsfileengine_unix.cpp b/src/corelib/io/qfsfileengine_unix.cpp index 6af5674..7824520 100644 --- a/src/corelib/io/qfsfileengine_unix.cpp +++ b/src/corelib/io/qfsfileengine_unix.cpp @@ -1250,6 +1250,12 @@ uchar *QFSFileEnginePrivate::map(qint64 offset, qint64 size, QFile::MemoryMapFla return 0; } + // If we know the mapping will extend beyond EOF, fail early to avoid + // undefined behavior. Otherwise, let mmap have its say. + if (doStat() + && (QT_OFF_T(size) > st.st_size - QT_OFF_T(offset))) + return 0; + int access = 0; if (openMode & QIODevice::ReadOnly) access |= PROT_READ; if (openMode & QIODevice::WriteOnly) access |= PROT_WRITE; |