CVE-2026-22980
High · 7.8CVSS
7.8
EPSS
0.1%
Published
Jan 23, 2026
CISA due date
—
The record
In the Linux kernel, the following vulnerability has been resolved: nfsd: provide locking for v4_end_grace Writing to v4_end_grace can race with server shutdown and result in memory being accessed after it was freed - reclaim_str_hashtbl in particularly. We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is held while client_tracking_op->init() is called and that can wait for an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a deadlock. nfsd4_end_grace() is also called by the landromat work queue and this doesn't require locking as server shutdown will stop the work and wait for it before freeing anything that nfsd4_end_grace() might access. However, we must be sure that writing to v4_end_grace doesn't restart the work item after shutdown has already waited for it. For this we add a new flag protected with nn->client_lock. It is set only while it is safe to make client tracking calls, and v4_end_grace only schedules work while the flag is set with the spinlock held. So this patch adds a nfsd_net field "client_tracking_active" which is set as described. Another field "grace_end_forced", is set when v4_end_grace is written. After this is set, and providing client_tracking_active is set, the laundromat is scheduled. This "grace_end_forced" field bypasses other checks for whether the grace period has finished. This resolves a race which can result in use-after-free.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 3.18.0 | 5.10.248 |
| openSUSE:Leap 16.0 | dtb-aarch64 | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-64kb | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-azure | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-default | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-default-base | 0 | 6.12.0-160000.27.1.160000.2.8 |
| openSUSE:Leap 16.0 | kernel-docs | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-kvmsmall | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-obs-build | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-obs-qa | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-rt | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-source | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-syms | 0 | 6.12.0-160000.27.1 |
| openSUSE:Leap 16.0 | kernel-zfcpdump | 0 | 6.12.0-160000.27.1 |
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