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

netfilter: nf_tables: skip netdev events generated on netns removal

syzbot reported following (harmless) WARN:

WARNING: CPU: 1 PID: 2648 at net/netfilter/core.c:468
nft_netdev_unregister_hooks net/netfilter/nf_tables_api.c:230 [inline]
nf_tables_unregister_hook include/net/netfilter/nf_tables.h:1090 [inline]
__nft_release_basechain+0x138/0x640 net/netfilter/nf_tables_api.c:9524
nft_netdev_event net/netfilter/nft_chain_filter.c:351 [inline]
nf_tables_netdev_event+0x521/0x8a0 net/netfilter/nft_chain_filter.c:382

reproducer:
unshare -n bash -c 'ip link add br0 type bridge; nft add table netdev t ; \
nft add chain netdev t ingress \{ type filter hook ingress device "br0" \
priority 0\; policy drop\; \}'

Problem is that when netns device exit hooks create the UNREGISTER
event, the .pre_exit hook for nf_tables core has already removed the
base hook. Notifier attempts to do this again.

The need to do base hook unregister unconditionally was needed in the past,
because notifier was last stage where reg->dev dereference was safe.

Now that nf_tables does the hook removal in .pre_exit, this isn't
needed anymore.
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 04 Nov 2024 12:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-05-04T12:41:29.470Z

Reserved: 2024-05-21T14:58:30.833Z

Link: CVE-2021-47452

cve-icon Vulnrichment

Updated: 2024-08-04T05:39:58.991Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2024-05-22T07:15:10.300

Modified: 2024-11-21T06:36:10.543

Link: CVE-2021-47452

cve-icon Redhat

Severity : Low

Publid Date: 2024-05-22T00:00:00Z

Links: CVE-2021-47452 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-07-12T23:06:15Z