Linux Kernel OCFS2 Data Corruption Vulnerability After Failed Write

A vulnerability in the Linux kernel's OCFS2 file system can lead to data corruption following a failed write operation. When a buffered write does not successfully transfer data to the underlying page cache, the function 'ocfs2_write_end_nolock()' improperly zeros out the page and marks it as dirty. This behavior can leave a dirty page extending beyond the end of the file. If the writeback process attempts to write this page before the write is completed and the file size is updated, the page can enter an inconsistent state. In this state, the page's dirty bit is cleared, but the buffer's dirty bits remain set, causing the data to be lost and not written out. The vulnerability has been addressed by invalidating the page beyond the end of the file after a write failure.

Impact

This vulnerability can result in data loss, as written data can be lost if the page writeback process is not properly synchronized with file size updates.