Bug 2360925 (CVE-2025-39688)

Summary: CVE-2025-39688 kernel: nfsd: allow SC_STATUS_FREEABLE when searching via nfs4_lookup_stateid()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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OS: Linux   
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Description OSIDB Bzimport 2025-04-18 08:01:30 UTC 
In the Linux kernel, the following vulnerability has been resolved:

nfsd: allow SC_STATUS_FREEABLE when searching via nfs4_lookup_stateid()

The pynfs DELEG8 test fails when run against nfsd. It acquires a
delegation and then lets the lease time out. It then tries to use the
deleg stateid and expects to see NFS4ERR_DELEG_REVOKED, but it gets
bad NFS4ERR_BAD_STATEID instead.

When a delegation is revoked, it's initially marked with
SC_STATUS_REVOKED, or SC_STATUS_ADMIN_REVOKED and later, it's marked
with the SC_STATUS_FREEABLE flag, which denotes that it is waiting for
s FREE_STATEID call.

nfs4_lookup_stateid() accepts a statusmask that includes the status
flags that a found stateid is allowed to have. Currently, that mask
never includes SC_STATUS_FREEABLE, which means that revoked delegations
are (almost) never found.

Add SC_STATUS_FREEABLE to the always-allowed status flags, and remove it
from nfsd4_delegreturn() since it's now always implied.
Comment 1 Avinash Hanwate 2025-04-18 13:37:12 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025041819-CVE-2025-39688-80f1@gregkh/T