CVE-2022-50241: NFSD: fix use-after-free on source server when doing inter-server copy

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-15 · updated 2026-10-15
Weakness: CWE-416

Description

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.

Affected products

Linux kernel: before 5.10.150; from 5.11 before 5.15.75; from 5.16 before 5.19.17; from 6.0 before 6.0.3 — fixed in 5.10.150, 5.15.75, 5.19.17, 6.0.3

How to fix

Upgrade to a fixed version: Linux kernel 5.10.150, 5.15.75, 5.19.17, 6.0.3. Check the vendor advisory for mitigations.

References

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