CVE-2026-89676

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

nfsd: fix stale s2scpstateids IDR entry for async COPY

For an async COPY, nfsd4copy() called nfs4initcopystate() before

dupcopyfields(), so the s2scpstateids IDR was pointed at

&u->copy->cp_stateid -- memory in the per-rqstp COMPOUND buffer that is

reused by the next request. dupcopyfields() copies only the value into

async_copy, so the IDR slot dangled at the transient buffer for the whole

background copy. Any IDR walker then dereferences reused request memory:

the laundromat reads cs_type from it and, if the bytes look like an

expired NFS4COPYNOTIFYSTID, follows into

refcountdec()/idrremove()/kfree() on garbage; managecpntfstate() has

the same exposure via idr_find().

Duplicate the fields first, then register the stateid on the stable

asynccopy. result->cbstateid is unchanged.