CoreCVE
Back

HIGH

nbd: defer config unlock in nbd_genl_connect

Published Dec 24, 2025

Description

There is one use-after-free warning when running NBD_CMD_CONNECT and NBD_CLEAR_SOCK:

nbd_genl_connect nbd_alloc_and_init_config // config_refs=1 nbd_start_device // config_refs=2 set NBD_RT_HAS_CONFIG_REF open nbd // config_refs=3 recv_work done // config_refs=2 NBD_CLEAR_SOCK // config_refs=1 close nbd // config_refs=0 refcount_inc -> uaf

------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 24 PID: 1014 at lib/refcount.c:25 refcount_warn_saturate+0x12e/0x290 nbd_genl_connect+0x16d0/0x1ab0 genl_family_rcv_msg_doit+0x1f3/0x310 genl_rcv_msg+0x44a/0x790

The issue can be easily reproduced by adding a small delay before refcount_inc(&nbd->config_refs) in nbd_genl_connect():

mutex_unlock(&nbd->config_lock); if (!ret) { set_bit(NBD_RT_HAS_CONFIG_REF, &config->runtime_flags); + printk("before sleep\n"); + mdelay(5 * 1000); + printk("after sleep\n"); refcount_inc(&nbd->config_refs); nbd_connect_reply(info, nbd->index); }

Affected products

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-911

References (13)

Change history (0)

No recorded changes yet.

Sources
CVE.org / MITRE
Status PUBLISHED
Assigner Linux
Published Dec 24, 2025
Updated Jun 16, 2026
Reserved Dec 16, 2025
Link CVE-2025-68366
CISA Vulnrichment
Updated Jun 16, 2026
NVD
Status Deferred
Modified Jun 17, 2026
Link CVE-2025-68366
Red Hat
Severity Moderate
Public date Dec 24, 2025
Links CVE-2025-68366 - Bugzilla