net: add more sanity checks to qdisc_pkt_len_init()

Vulnerability 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.

References

• https://git.kernel.org/stable/c/d7d1a28f5dd57b4d83def876f8d7b4403bd37df9
• https://git.kernel.org/stable/c/473426a1d53a68dd1e718e6cd00d57936993fa6c
• 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