Missed edge case when resizing the memorymapped file in UserDefault that could cause a crash

theunwisewolf · theunwisewolf · commit 797a41b469e1 · 2022-08-02T16:13:12.000+05:30
diff --git a/core/base/CCUserDefault.cpp b/core/base/CCUserDefault.cpp
@@ -484,7 +484,9 @@ void UserDefault::flush()
         if (obs.length() > _curMapSize)
         {
             _rwmmap->unmap();
-            _curMapSize <<= 1;  // X2
+            while (obs.length() > _curMapSize)
+                _curMapSize <<= 1;  // X2
+                
             posix_fsetsize(_fd, _curMapSize);
             _rwmmap->map(posix_fd2fh(_fd), 0, _curMapSize, error);
         }

Original file line number	Diff line number	Diff line change
`@@ -484,7 +484,9 @@ void UserDefault::flush()`
`484`	`484`	`if (obs.length() > _curMapSize)`
`485`	`485`	`{`
`486`	`486`	`_rwmmap->unmap();`
`487`		`- _curMapSize <<= 1; // X2`
	`487`	`+ while (obs.length() > _curMapSize)`
	`488`	`+ _curMapSize <<= 1; // X2`
	`489`	`+`
`488`	`490`	`posix_fsetsize(_fd, _curMapSize);`
`489`	`491`	`_rwmmap->map(posix_fd2fh(_fd), 0, _curMapSize, error);`
`490`	`492`	`}`