Description

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

nfsd: Initialize ssc before laundromat_work to prevent NULL dereference

In nfs4_state_start_net(), laundromat_work may access nfsd_ssc through
nfs4_laundromat -> nfsd4_ssc_expire_umount. If nfsd_ssc isn't initialized,
this can cause NULL pointer dereference.

Normally the delayed start of laundromat_work allows sufficient time for
nfsd_ssc initialization to complete. However, when the kernel waits too
long for userspace responses (e.g. in nfs4_state_start_net ->
nfsd4_end_grace -> nfsd4_record_grace_done -> nfsd4_cld_grace_done ->
cld_pipe_upcall -> __cld_pipe_upcall -> wait_for_completion path), the
delayed work may start before nfsd_ssc initialization finishes.

Fix this by moving nfsd_ssc initialization before starting laundromat_work.

Classification

CVE ID: CVE-2025-38231

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.02% (probability of being exploited)

EPSS Percentile: 4.96% (scored less or equal to compared to others)

EPSS Date: 2025-07-06 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2025-38231
https://git.kernel.org/stable/c/deaeb74ae9318252829c59a84a7d2316fc335660
https://git.kernel.org/stable/c/0fccf5f01ed28725cc313a66ca1247eef911d55e
https://git.kernel.org/stable/c/a97668ec6d73dab237cd1c15efe012a10090a4ed
https://git.kernel.org/stable/c/5060e1a5fef184bd11d298e3f0ee920d96a23236
https://git.kernel.org/stable/c/d622c2ee6c08147ab8c9b9e37d93b6e95d3258e0
https://git.kernel.org/stable/c/83ac1ba8ca102ab5c0ed4351f8ac6e74ac4d5d64
https://git.kernel.org/stable/c/b31da62889e6d610114d81dc7a6edbcaa503fcf8

Timeline