Description

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

NFSD: fix hang in nfsd4_shutdown_callback

If nfs4_client is in courtesy state then there is no point to send
the callback. This causes nfsd4_shutdown_callback to hang since
cl_cb_inflight is not 0. This hang lasts about 15 minutes until TCP
notifies NFSD that the connection was dropped.

This patch modifies nfsd4_run_cb_work to skip the RPC call if
nfs4_client is in courtesy state.

Classification

CVE ID: CVE-2025-21795

Affected Products

Vendor: Linux, Linux

Product: Linux, Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 9.05% (scored less or equal to compared to others)

EPSS Date: 2025-03-27 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2025-21795
https://git.kernel.org/stable/c/38d345f612503b850c2973e5a879f88e441b34d7
https://git.kernel.org/stable/c/23ad7797c74cd8f7f90617f1e59a8703e2b43908
https://git.kernel.org/stable/c/cedfbb92cf97a6bff3d25633001d9c44442ee854
https://git.kernel.org/stable/c/e88d2451cd42e025465d6b51fd716a47b0b3800d
https://git.kernel.org/stable/c/036ac2778f7b28885814c6fbc07e156ad1624d03

Timeline