CVE-2024-49978: linux kernel Null Dereference — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: gso: fix udp gso fraglist segmentation after pull from frag_list Detect 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 UDP, this causes a NULL ptr deref in __udpv4_gso_segment_list_csum at udp_hdr(seg->next)->dest. 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.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.6 — 6.1.113
linux	linux_kernel	6.2 — 6.6.55
linux	linux_kernel	6.7 — 6.10.14
linux	linux_kernel	6.11 — 6.11.3
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/080e6c9a3908de193a48f646c5ce1bfb15676ffc https://git.kernel.org/stable/c/33e28acf42ee863f332a958bfc2f1a284a3659df https://git.kernel.org/stable/c/3cd00d2e3655fad3bda96dc1ebf17b6495f86fea https://git.kernel.org/stable/c/a1e40ac5b5e9077fe1f7ae0eb88034db0f9ae1ab https://git.kernel.org/stable/c/af3122f5fdc0d00581d6e598a668df6bf54c9daa

Other References

https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html

Frequently Asked Questions

What is CVE-2024-49978? +

In the Linux kernel, the following vulnerability has been resolved: gso: fix udp gso fraglist segmentation after pull from frag_list Detect 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 UDP, this causes a NULL ptr deref in __udpv4_gso_segment_list_csum at udp_hdr(seg->next)->dest. 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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2024-49978? +

CVE-2024-49978 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2024-49978? +

CVE-2024-49978 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-49978? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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