CVE-2021-47452 Affecting kernel-rt-kvm package, versions *


Severity

low

    Threat Intelligence

    EPSS
    0.04% (9th percentile)

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  • Snyk ID SNYK-CENTOS7-KERNELRTKVM-7077558
  • published 23 May 2024
  • disclosed 22 May 2024

Introduced: 22 May 2024

New CVE-2021-47452 Open this link in a new tab

How to fix?

There is no fixed version for Centos:7 kernel-rt-kvm.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-kvm package and not the kernel-rt-kvm package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

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.

CVSS Scores

version 3.1
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Snyk

5.5 low
  • Attack Vector (AV)
    Local
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    Low
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    None
  • Integrity (I)
    None
  • Availability (A)
    High
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Red Hat

5.5 medium
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SUSE

5.5 medium