CVE-2022-49340 Affecting kernel-rt package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

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  • Snyk IDSNYK-RHEL7-KERNELRT-9026191
  • published2 Mar 2025
  • disclosed26 Feb 2025

Introduced: 26 Feb 2025

NewCVE-2022-49340  (opens in a new tab)

How to fix?

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

NVD Description

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

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

ip_gre: test csum_start instead of transport header

GRE with TUNNEL_CSUM will apply local checksum offload on CHECKSUM_PARTIAL packets.

ipgre_xmit must validate csum_start after an optional skb_pull, else lco_csum may trigger an overflow. The original check was

if (csum && skb_checksum_start(skb) < skb->data)
    return -EINVAL;

This had false positives when skb_checksum_start is undefined: when ip_summed is not CHECKSUM_PARTIAL. A discussed refinement was straightforward

if (csum && skb->ip_summed == CHECKSUM_PARTIAL &&
    skb_checksum_start(skb) < skb->data)
    return -EINVAL;

But was eventually revised more thoroughly:

  • restrict the check to the only branch where needed, in an uncommon GRE path that uses header_ops and calls skb_pull.
  • test skb_transport_header, which is set along with csum_start in skb_partial_csum_set in the normal header_ops datapath.

Turns out skbs can arrive in this branch without the transport header set, e.g., through BPF redirection.

Revise the check back to check csum_start directly, and only if CHECKSUM_PARTIAL. Do leave the check in the updated location. Check field regardless of whether TUNNEL_CSUM is configured.

CVSS Scores

version 3.1