CVE-2026-90155

Summary

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

ksmbd: detach blocked lock requests before freeing

A file_lock retained by ksmbd for byte-range lock bookkeeping can still be part of the VFS blocked-request graph. In particular, the VFS can chain a new waiter below an already blocked request through flc_blocked_requests. The ksmbd_file reference count does not cover that graph.

Both __ksmbd_close_fd() and the cross-request unlock path free these retained file_lock objects directly. If a dependent waiter is still attached, locks_release_private() hits BUG_ON(!list_empty(&flc->flc_blocked_requests)). The same lifetime mismatch can leave a freed ksmbd_lock reachable through its request-local llist.

Detach the file_lock from the blocked-request graph before freeing it in the close, cross-request unlock, and rollback paths. locks_delete_block() also wakes requests chained below the object. Remove llist when a completed lock is published so a globally visible ksmbd_lock no longer points into the submitting worker's stack.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/514a0b2bc949963497e66cacd433f65dc768a71d
• https://git.kernel.org/stable/c/215e8816b1ac25176d911abb8704390413ccee4b

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