CVE-2022-50241

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

NFSD: fix use-after-free on source server when doing inter-server copy

Use-after-free occurred when the laundromat tried to free expired

cpntf_state entry on the s2s_cp_stateids list after inter-server

copy completed. The sc_cp_list that the expired copy state was

inserted on was already freed.

When COPY completes, the Linux client normally sends LOCKU(lock_state x),

FREE_STATEID(lock_state x) and CLOSE(open_state y) to the source server.

The nfs4_put_stid call from nfsd4_free_stateid cleans up the copy state

from the s2s_cp_stateids list before freeing the lock state's stid.

However, sometimes the CLOSE was sent before the FREE_STATEID request.

When this happens, the nfsd4_close_open_stateid call from nfsd4_close

frees all lock states on its st_locks list without cleaning up the copy

state on the sc_cp_list list. When the time the FREE_STATEID arrives the

server returns BAD_STATEID since the lock state was freed. This causes

the use-after-free error to occur when the laundromat tries to free

the expired cpntf_state.

This patch adds a call to nfs4_free_cpntf_statelist in

nfsd4_close_open_stateid to clean up the copy state before calling

free_ol_stateid_reaplist to free the lock state's stid on the reaplist.