AZL-99474

In the Linux kernel, the following vulnerability has been resolved:

fuse: fix invalidate lock leak on open O_TRUNC DAX failure

fuseopen() takes filemapinvalidatelock() for a DAX truncate (daxtruncate = true) and releases it before the outinodeunlock label. But when fusedaxbreaklayouts() fails, the goto outinode_unlock skips the unlock and leaks the rwsem, so any later fault or truncate on the file stalls on the stale lock.

fusedaxbreak_layouts() can fail with -ERESTARTSYS when a signal interrupts the wait for busy DAX pages to drain:

open("file", ORDWR | OTRUNC) └─ fuseopen() ├─ filemapinvalidatelock() # daxtruncate └─ fusedaxbreaklayouts() └─ daxbreaklayout() └─ waitpageidle() # TASKINTERRUPTIBLE └─ fusewaitdaxpage() # unlock, schedule, re-lock └─ signal → -ERESTARTSYS goto outinode_unlock # <- lock leaked

Fix this by moving filemapinvalidateunlock() 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.