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CVE-2024-35839 Affecting kernel-rt-debug-modules-core package, versions <0:5.14.0-427.33.1.el9_4

Severity

 Recommended
high

Based on AlmaLinux security rating

    Threat Intelligence

    EPSS
    0.05% (17th percentile)

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  • Snyk ID SNYK-ALMALINUX9-KERNELRTDEBUGMODULESCORE-8331957
  • published 4 Nov 2024
  • disclosed 28 Aug 2024
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Introduced: 28 Aug 2024

CVE-2024-35839 Open this link in a new tab

How to fix?

Upgrade AlmaLinux:9 kernel-rt-debug-modules-core to version 0:5.14.0-427.33.1.el9_4 or higher.
This issue was patched in ALSA-2024:5928.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-modules-core package and not the kernel-rt-debug-modules-core package as distributed by AlmaLinux. See How to fix? for AlmaLinux:9 relevant fixed versions and status.

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

netfilter: bridge: replace physindev with physinif in nf_bridge_info

An skb can be added to a neigh->arp_queue while waiting for an arp reply. Where original skb's skb->dev can be different to neigh's neigh->dev. For instance in case of bridging dnated skb from one veth to another, the skb would be added to a neigh->arp_queue of the bridge.

As skb->dev can be reset back to nf_bridge->physindev and used, and as there is no explicit mechanism that prevents this physindev from been freed under us (for instance neigh_flush_dev doesn't cleanup skbs from different device's neigh queue) we can crash on e.g. this stack:

arp_process neigh_update skb = __skb_dequeue(&neigh->arp_queue) neigh_resolve_output(..., skb) ... br_nf_dev_xmit br_nf_pre_routing_finish_bridge_slow skb->dev = nf_bridge->physindev br_handle_frame_finish

Let's use plain ifindex instead of net_device link. To peek into the original net_device we will use dev_get_by_index_rcu(). Thus either we get device and are safe to use it or we don't get it and drop skb.

CVSS Scores

version 3.1
Expand this section

Red Hat

5.5 medium
  • 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