CVE-2021-47179: NFSv4: Fix a NULL pointer dereference in pnfs_mark_matching_lsegs_return()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-03-25 · updated 2026-08-04
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: NFSv4: Fix a NULL pointer dereference in pnfs_mark_matching_lsegs_return() Commit de144ff4234f changes _pnfs_return_layout() to call pnfs_mark_matching_lsegs_return() passing NULL as the struct pnfs_layout_range argument. Unfortunately, pnfs_mark_matching_lsegs_return() doesn't check if we have a value here before dereferencing it, causing an oops. I'm able to hit this crash consistently when running connectathon basic tests on NFS v4.1/v4.2 against Ontap.

Affected products

Linux kernel: from 4.9.269 before 4.9.271; from 4.14.233 before 4.14.235; from 4.19.191 before 4.19.193; from 5.4.118 before 5.4.124; from 5.10.36 before 5.10.42; from 5.12.3 before 5.12.9 — fixed in 4.14.235, 4.19.193, 4.9.271, 5.10.42, 5.12.9, 5.4.124

How to fix

Upgrade to a fixed version: Linux kernel 4.14.235, 4.19.193, 4.9.271, 5.10.42. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2021-47179 or the next vulnerability affects your stack