CVE-2026-80855

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CVE-2026-80855

Summary: fuse: fix invalidate lock leak on open O_TRUNC DAX failure

Details: In the Linux kernel, the following vulnerability has been resolved: fuse: fix invalidate lock leak on open O_TRUNC DAX failure fuse_open() takes filemap_invalidate_lock() for a DAX truncate (dax_truncate = true) and releases it before the out_inode_unlock label. But when fuse_dax_break_layouts() fails, the goto out_inode_unlock skips the unlock and leaks the rwsem, so any later fault or truncate on the file stalls on the stale lock. fuse_dax_break_layouts() can fail with -ERESTARTSYS when a signal interrupts the wait for busy DAX pages to drain: open("file", O_RDWR | O_TRUNC) └─ fuse_open() ├─ filemap_invalidate_lock() # dax_truncate └─ fuse_dax_break_layouts() └─ dax_break_layout() └─ wait_page_idle() # TASK_INTERRUPTIBLE └─ fuse_wait_dax_page() # unlock, schedule, re-lock └─ signal → -ERESTARTSYS goto out_inode_unlock # <- lock leaked Fix this by moving filemap_invalidate_unlock() below the label so that all error paths release the lock, and rename the label to out_unlock as it now covers more than just the inode lock.

References: https://git.kernel.org/stable/c/1b04d80a27d317064cce2307472f5bef9975bc50, https://git.kernel.org/stable/c/1d3e701cda2f41d48aa721b3ebefbe0fbf8d74da, https://git.kernel.org/stable/c/7288c279ddbd654a06c82118c1a3f5570c1807f0, https://git.kernel.org/stable/c/776e85fda752f9a15e0f82dec42ecacd12a9bd94, https://git.kernel.org/stable/c/a61524da59a2f5ac9c8de23ff98b30da769ab144, https://git.kernel.org/stable/c/a927f1867e61b78f39f9da0bbba3c98c2ca151fe, https://git.kernel.org/stable/c/dcf30a56624c2a0cfab1bada5b1ca8cc0c02f010, https://git.kernel.org/stable/c/e981474d7bf1457da12404e169ea147d2c8ecea7, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80855.json, https://nvd.nist.gov/vuln/detail/CVE-2026-80855, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git