CVE-2024-49979: net: gso: fix tcp fraglist segmentation after pull from frag_list

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-10-21 · updated 2026-08-04
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: net: gso: fix tcp fraglist segmentation after pull from frag_list Detect tcp gso fraglist skbs with corrupted geometry (see below) and pass these to skb_segment instead of skb_segment_list, as the first can segment them correctly. Valid SKB_GSO_FRAGLIST skbs - consist of two or more segments - the head_skb holds the protocol headers plus first gso_size - one or more frag_list skbs hold exactly one segment - all but the last must be gso_size Optional datapath hooks such as NAT and BPF (bpf_skb_pull_data) can modify these skbs, breaking these invariants. In extreme cases they pull all data into skb linear. For TCP, this causes a NULL ptr deref in __tcpv4_gso_segment_list_csum at tcp_hdr(seg->next). Detect invalid geometry due to pull, by checking head_skb size. Don't just drop, as this may blackhole a destination. Convert to be able to pass to regular skb_segment. Approach and description based on a patch by Willem de Bruijn.

Affected products

Linux kernel: from 6.10 before 6.10.14; from 6.11 before 6.11.3; 6.12-rc1 — fixed in 6.10.14, 6.11.3

How to fix

Upgrade to a fixed version: Linux kernel 6.10.14, 6.11.3. Check the vendor advisory for mitigations.

References

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