ensure returned Component refers to valid memory

* we have seen some core dumps in logctl when using
  the mmap'ed levels inside a Component.  Add extra
  checks to ensure we stay inside the actual file.

1 files changed, 2 insertions, 0 deletions

diff --git a/vespalog/src/vespa/log/control-file.h b/vespalog/src/vespa/log/control-file.h
index d0fb211e202..886f38791ba 100644
--- a/vespalog/src/vespa/log/control-file.h
+++ b/vespalog/src/vespa/log/control-file.h
@@ -17,6 +17,7 @@ public:
     enum Mode { READONLY, READWRITE, CREATE };
 private:
     Lock _fileBacking;
+    int _fileSize;
     enum Mode _mode;
     char *_fileName;
     void ensureHeader();
@@ -56,6 +57,7 @@ public:
     ~ControlFile();
     unsigned int *getLevels(const char *name);
     void ensureComponent(const char *pattern);
+    bool insideFile(char *p) { return (p >= _mapBase) && (p < _mapBase + _fileSize); }
 
     static unsigned int *defaultLevels();