fuse: fix invalidate lock leak on open O_TRUNC DAX failure

Overview

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.

Affected

• Linux >= d58366aab86854217b81679d1a9dcd54a2edfc2a < 1b04d80a27d317064cce2307472f5bef9975bc50
• Linux >= 2fdbb8dd01556e1501132b5ad3826e8f71e24a8b < a61524da59a2f5ac9c8de23ff98b30da769ab144
• Linux >= 2fdbb8dd01556e1501132b5ad3826e8f71e24a8b < dcf30a56624c2a0cfab1bada5b1ca8cc0c02f010
• Linux >= 2fdbb8dd01556e1501132b5ad3826e8f71e24a8b < 7288c279ddbd654a06c82118c1a3f5570c1807f0
• Linux >= 2fdbb8dd01556e1501132b5ad3826e8f71e24a8b < 776e85fda752f9a15e0f82dec42ecacd12a9bd94
• Linux >= 2fdbb8dd01556e1501132b5ad3826e8f71e24a8b < 1d3e701cda2f41d48aa721b3ebefbe0fbf8d74da
• Linux >= 2fdbb8dd01556e1501132b5ad3826e8f71e24a8b < e981474d7bf1457da12404e169ea147d2c8ecea7
• Linux >= 2fdbb8dd01556e1501132b5ad3826e8f71e24a8b < a927f1867e61b78f39f9da0bbba3c98c2ca151fe
• Linux 81775ab858b4236c52c5da7e25cec6e49dd91b46
• Linux b57e150ac2eac791d5d187923b73dc2dafaf67fa
• Linux 1fdbbe246daf348adaa0739463384b16ceba1fc0
• Linux >= 5.15.109 < 5.15.220
• Linux >= 5.10.179 < 5.11
• Linux >= 5.18.18 < 5.19
• Linux >= 5.19.2 < 5.20
• Linux 6.0

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.