Withdrawn by the publisher.

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

NFSD: Release the export reference when reaping open stateids

nfs4_put_stid() releases the svc_export tracked in nfs4_stid.sc_export, but free_ol_stateid_reaplist() frees open and lock stateids by calling ->sc_free() directly, bypassing that path. An open stateid takes an sc_export reference in nfs4_open() and a lock stateid takes its own in init_lock_stateid(); both reach free_ol_stateid_reaplist() through their normal teardown, the open stateid via release_open_stateid() and the lock stateid via nfsd4_release_lockowner(), each through put_ol_stateid_locked(). The reference is therefore never dropped, pinning the export and blocking unmount for the lifetime of the stateid.

Release sc_export in free_ol_stateid_reaplist() the way nfs4_put_stid() does. ->sc_free() runs once per stateid, and a stateid reaches free_ol_stateid_reaplist() or nfs4_put_stid() but never both, so the reference is dropped exactly once. Revoked stateids reach this path with sc_export already cleared by drop_stid_export(), so they are skipped rather than double-freed.

nfs4_put_stid() itself read sc_export before acquiring cl_lock. drop_stid_export() clears that field and releases the reference under cl_lock, so a concurrent revocation could drop the export in the window between the read and the final put, releasing the same reference twice. Read sc_export while cl_lock is held so the two paths serialize and the reference is released…

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

NFSD: Release the export reference when reaping open stateids

nfs4_put_stid() releases the svc_export tracked in nfs4_stid.sc_export, but free_ol_stateid_reaplist() frees open and lock stateids by calling ->sc_free() directly, bypassing that path. An open stateid takes an sc_export reference in nfs4_open() and a lock stateid takes its own in init_lock_stateid(); both reach free_ol_stateid_reaplist() through their normal teardown, the open stateid via release_open_stateid() and the lock stateid via nfsd4_release_lockowner(), each through put_ol_stateid_locked(). The reference is therefore never dropped, pinning the export and blocking unmount for the lifetime of the stateid.

Release sc_export in free_ol_stateid_reaplist() the way nfs4_put_stid() does. ->sc_free() runs once per stateid, and a stateid reaches free_ol_stateid_reaplist() or nfs4_put_stid() but never both, so the reference is dropped exactly once. Revoked stateids reach this path with sc_export already cleared by drop_stid_export(), so they are skipped rather than double-freed.

nfs4_put_stid() itself read sc_export before acquiring cl_lock. drop_stid_export() clears that field and releases the reference under cl_lock, so a concurrent revocation could drop the export in the window between the read and the final put, releasing the same reference twice. Read sc_export while cl_lock is held so the two paths serialize and the reference is released…

kernel-devel-7.2.7-1.1 on GA media

Affected: Ubuntu:16.04:LTS: linux-hwe-edge, Ubuntu:18.04:LTS: linux-aws-5.0, Ubuntu:18.04:LTS: linux-aws-5.3, Ubuntu:18.04:LTS: linux-azure, Ubuntu:18.04:LTS: linux-azure-5.3, Ubuntu:18.04:LTS: linux-azure-edge, Ubuntu:18.04:LTS: linux-gcp, Ubuntu:18.04:LTS: linux-gcp-5.3, Ubuntu:18.04:LTS: linux-gke-4.15, Ubuntu:18.04:LTS: linux-gke-5.4 and 96 more

In the Linux kernel, the following vulnerability has been resolved: NFSD: Release the export reference when reaping open stateids nfs4_put_stid() releases the svc_export tracked in nfs4_stid.sc_export, but free_ol_stateid_reaplist() frees open and lock stateids by calling ->sc_free() directly, bypassing that path. An open stateid takes an sc_export reference in nfs4_open() and a lock stateid takes its own in init_lock_stateid(); both reach free_ol_stateid_reaplist() through their normal teardown, the open stateid via release_open_stateid() and the lock stateid via nfsd4_release_lockowner(), each through put_ol_stateid_locked(). The reference is therefore never dropped, pinning the export and blocking unmount for the lifetime of the stateid. Release sc_export in free_ol_stateid_reaplist() the way nfs4_put_stid() does. ->sc_free() runs once per stateid, and a stateid reaches free_ol_stateid_reaplist() or nfs4_put_stid() but never both, so the reference is dropped exactly once. Revoked stateids reach this path with sc_export already cleared by drop_stid_export(), so they are skipped rather than double-freed. nfs4_put_stid() itself read sc_export before acquiring cl_lock. drop_stid_export() clears that field and releases the reference under cl_lock, so a concurrent revocation could drop the export in the window between the read and the final put, releasing the same reference twice. Read sc_export while cl_lock is held so the two paths serialize and the reference is released exac…

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel möglicherweise ausnutzen, um Berechtigungen zu erweitern, Sicherheitsmaßnahmen zu umgehen, Daten offenzulegen oder zu manipulieren, den Speicher zu beschädigen, Denial-of-Service-Zustände zu verursachen oder andere, nicht näher spezifizierte Angriffe durchzuführen.