CVE-2026-45983

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

nfsd: never defer requests during idmap lookup

During v4 request compound arg decoding, some ops (e.g. SETATTR) can trigger idmap lookup upcalls. When those upcall responses get delayed beyond the allowed time limit, cache_check() will mark the request for deferral and cause it to be dropped.

This prevents nfs4svcencodecompoundres from being executed, and thus the session slot flag NFSD4SLOTINUSE never gets cleared. Subsequent client requests will fail with NFSERR_JUKEBOX, given that the slot will be marked as in-use, making the SEQUENCE op fail.

Fix this by making sure that the RQUSEDEFERRAL flag is always clear during nfs4svcdecode_compoundargs(), since no v4 request should ever be deferred.