CVE-2024-49948 Information

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.

Reference

https://git.kernel.org/stable/c/566a931a1436d0e0ad13708ea55479b95426213c https://git.kernel.org/stable/c/2415f465730e48b6e38da1c7c097317bf5dd2d20 https://git.kernel.org/stable/c/27a8fabc54d2f960d47bdfbebf2bdc6e8a92a4c4 https://git.kernel.org/stable/c/9b0ee571d20a238a22722126abdfde61f1b2bdd0 https://git.kernel.org/stable/c/ff1c3cadcf405ab37dd91418a62a7acecf3bc5e2 https://git.kernel.org/stable/c/1eebe602a8d8264a12e35e39d0645fa88dbbacdd https://git.kernel.org/stable/c/ab9a9a9e9647392a19e7a885b08000e89c86b535