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Fencer Vulns
medium 4.7

CVE-2022-49300 json

nbd: fix race between nbd_alloc_config() and module removal

published 2025-02-26 20 mo ago modified 2026-06-17 4 mo ago also EUVD-2022-54927

cvss
4.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

Summary

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

nbd: fix race between nbd_alloc_config() and module removal

When nbd module is being removing, nbd_alloc_config() may be called concurrently by nbd_genl_connect(), although try_module_get() will return false, but nbd_alloc_config() doesn't handle it.

The race may lead to the leak of nbd_config and its related resources (e.g, recv_workq) and oops in nbd_read_stat() due to the unload of nbd module as shown below:

BUG: kernel NULL pointer dereference, address: 0000000000000040 Oops: 0000 [#1] SMP PTI CPU: 5 PID: 13840 Comm: kworker/u17:33 Not tainted 5.14.0+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Workqueue: knbd16-recv recv_work [nbd] RIP: 0010:nbd_read_stat.cold+0x130/0x1a4 [nbd] Call Trace: recv_work+0x3b/0xb0 [nbd] process_one_work+0x1ed/0x390 worker_thread+0x4a/0x3d0 kthread+0x12a/0x150 ret_from_fork+0x22/0x30

Fixing it by checking the return value of try_module_get() in nbd_alloc_config(). As nbd_alloc_config() may return ERR_PTR(-ENODEV), assign nbd->config only when nbd_alloc_config() succeeds to ensure the value of nbd->config is binary (valid or NULL).

Also adding a debug message to check the reference counter of nbd_config during module removal.

Patch / fix

  • Linux Linux 4.14.283, 4.19.247, 5.4.198, 5.10.122, 5.15.47, 5.17.15, 5.18.4, 5.19
  • linux Debian 14, Debian 13, Debian 12 5.18.5-1

debian advisories DEBIAN-CVE-2022-49300

  • linux Ubuntu 18.04 LTS 4.15.0-192.203
  • linux Ubuntu 20.04 LTS 5.4.0-126.142
  • linux Ubuntu 22.04 LTS 5.15.0-48.54
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1140.151
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1085.92
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1020.24
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1089.97
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1018.24

ubuntu advisories UBUNTU-CVE-2022-49300

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-64kb SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS, Enterprise Storage 7.1 5.3.18-150300.59.201.1
  • kernel-syms SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.201.1
  • kernel-source SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.201.1
  • kernel-default SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +5 more 5.3.18-150300.59.201.1
  • kernel-preempt SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.201.1
  • kernel-obs-build SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.201.1
  • kernel-default-base SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +3 more 5.3.18-150300.59.201.1.150300.18.120.1
  • kernel-64kb SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS, SLE High Performance Computing 15 SP5-ESPOS 5.14.21-150500.55.100.1

suse advisories SUSE-SU-2025:1293-1SUSE-SU-2025:1263-1SUSE-SU-2025:1241-1SUSE-SU-2025:1194-1SUSE-SU-2025:1183-1SUSE-SU-2025:1176-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2022-49300 updated cvss 4.7

kernel: nbd: fix race between nbd_alloc_config() and module removal

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
13 mo ago

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-476 NULL Pointer Dereference
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.