DAX Truncate Lock Leak in Linux Kernel Affects System Performance

CVE-2026-80855

What is CVE-2026-80855?

In the Linux kernel, a lock management issue has been identified that occurs during the DAX truncate operation. The vulnerability arises within the fuse_open() function, where a filemap_invalidate_lock() is acquired for a DAX truncate operation. In failure scenarios, specifically when the fuse_dax_break_layouts() function encounters an error, the unlocking of the lock is skipped, resulting in a leak. This leads to potential stalling of further operations on the file, as subsequent calls to fault or truncate cannot proceed due to the stale lock. The resolution involves reordering the unlock mechanism to ensure that all error paths properly release the lock, enhancing system reliability and performance.

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