CVE-2024-49979 net: gso: fix tcp fraglist segmentation after pull from frag_list
A null pointer dereference in the Linux kernel TCP GSO segmentation allows remote attackers to cause a denial of service via crafted network packets.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-49979?
CVE-2024-49979 is a high-severity vulnerability in Linux kernel, published on 21 Oct 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-476
Which versions are affected by CVE-2024-49979?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-49979?
Apply the vendor's patch.
Is CVE-2024-49979 being exploited?
There is no known exploitation of CVE-2024-49979 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-49979, DEBIAN-CVE-2024-49979, GHSA-j4xv-h5fv-6v4m, UBUNTU-CVE-2024-49979.