CVE-2024-49948: net: add more sanity checks to qdisc_pkt_len_init()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-10-21 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: net: add more sanity checks to qdisc_pkt_len_init() One path takes care of SKB_GSO_DODGY, assuming skb->len is bigger than hdr_len. virtio_net_hdr_to_skb() does not fully dissect TCP headers, it only make sure it is at least 20 bytes. It is possible for an user to provide a malicious 'GSO' packet, total length of 80 bytes. - 20 bytes of IPv4 header - 60 bytes TCP header - a small gso_size like 8 virtio_net_hdr_to_skb() would declare this packet as a normal GSO packet, because it would see 40 bytes of payload, bigger than gso_size. We need to make detect this case to not underflow qdisc_skb_cb(skb)->pkt_len.

Affected products

Linux kernel: from 3.9 before 4.19.323; from 4.20 before 5.4.285; from 5.5 before 5.10.227; from 5.11 before 5.15.168; from 5.16 before 6.1.113; from 6.2 before 6.6.55 — fixed in 4.19.323, 5.10.227, 5.15.168, 5.4.285, 6.1.113, 6.10.14

How to fix

Upgrade to a fixed version: Linux kernel 4.19.323, 5.10.227, 5.15.168, 5.4.285. Check the vendor advisory for mitigations.

References

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